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Discount only 1 week to go!
Write awesome browser code with Smart Pascal
The fantastic $99 and $199 discount for Smart Mobile Studio professional and enterprise is about to expire! Only one week left of this extreme discount — so no time to waste!
You will get your license just in time for the next major update — so this is your chance to get the de-facto, #1 object pascal to JavaScript compiler at a massive 50% discount (!)
In short — the discount expires Sunday 20’th of Juli
How do I order?
Simple. Head over to http://www.smartmobilestudio.com and go to our order page. Remember to mark your order with “JLA” which is the discount code word. And that’s it.
You get all the updates for a whole year (and that is a very, very good deal).
Read the original discount post here.
Why is this cool?
Smart Pascal is the natural Delphi replacement for the web. It has also been called “A complete Adobe Flash replacement” and “What HTML5 Builder should have been”. You can use it to write mobile applications that run on your iOS or Android devices, interface with your native Delphi databases or back-end servers — and even to control hardware that run JavaScript (yes, more and more embedded boards and micro-controllers run JavaScript).
Leverage your Object Pascal knowledge for the next generation, HTML5 based application development!
Why spend six months writing elementary JavaScript – when you can do it in 6 days using Smart Pascal? Fully object-oriented, inheritance, RTTI, interfaces — all the benefits of a modern, high-level language running in your browsers.
No dependencies. No limits — just pure Smart Pascal!
Dataset for Smart Mobile Studio – Update
Yesterday I posted a preliminary dataset class for Smart Mobile Studio which is perfect for client-side HTML5 development. I have since spent a couple of hours more working on the unit, and here is the update. Still a few tweaks here and there, but in general it’s now usable, stable and persistent (!). This was a very interesting and rewarding task 🙂
Some of the updates since my last post:
- Schema is now defined in FieldDef classes (just like Delphi)
- Calculated (read: generated) fields are now supported
- Autoinc field class added
- GUID field class added
- Field-Definition IO in JSON format is in place
- Dataset can now load and save to JSON format as well
- Added Append() method for inserting record at the end of a dataset
- Altered Insert() method, allowing for insertion at any position (except -1 [BOF] and Count+1 [EOF]).
- Added MoveTo() method for absolute navigation
- Further abstracted architecture
- Exception handling in place
- More events (and more to come)
- Cleaned up source and re-factored quite a few procs
About the GUID calculated field
Javascript doesnt support GUID’s directly. There is no CreateGUID() or GUIDToString() provided by the browser. But thankfully the modern RFC for GUID generation allows for random numbers. So the GUID field is simply an auto-generated GUID string. If you for some reason want to avoid integer autoinc identifiers – but need unique field values (non editable) then TGUIDField is your class.
Note: In retrospect it makes sense to rename these fields to “generated fields”, since calculated fields are event based and user-definable. But I am still in the prototype stage when it comes to this code, so bear with me while I finish it.
How to use it
The dataset follows the ordinary BOF/EOF style navigation. Meaning that BOF (beginning of file) is at position -1 rather than zero, while EOF (end of file) is Count+1. The record pointer self-adjusts if you attempt an insert at these points. Where EOF results in an append, while insert(BOF) adds a record at the top of the dataset (position zero).
Other than that, it’s fairly straight shooting.
If you are going to have a global dataset in your Smart Pascal app’s, the best place to create it is in the project source – as a part of your project’s TApplication instance. All Smart Pascal applications have a unique TApplication object (not static like under Delphi), so this is the perfect place to initialize the dataset instance. Then you can typecast from any form to reach it (e.g: TApplication(application).Dataset).
Speed
It’s not going to make Bill Gates lose sleep any time soon, but I was surprised at how fast it works. This has more to do with the fact that it functions more like an array of variants, where each variant represents a JSON object (array of named values) than anything else. 1000 Inserts of the example below takes less than 1 second. It’s hard to measure it since it hardly makes a dent in the tick-counter.
So all in all it’s perfectly suited for Smart Mobile Studio projects. And when you compile with phonegap it’s even faster since the latest Cordova extensions for iOS boosts array operations considerably.
Procedure TForm1.TestDataset;
var
mDataset: TW3CustomDataset;
x:Integer;
mId: Integer;
begin
mDataset:=TW3CustomDataset.Create;
try
mDataset.FieldDefs.add('id',ftAutoInc);
mDataset.FieldDefs.add('key',ftGUID);
mDataset.FieldDefs.add('name',ftString);
mDataset.createDataset;
for x:=1 to 50 do
Begin
mDataset.Append;
mId:=mDataset.Fields.FieldByName('id').asInteger;
mDataset.Fields.FieldByName('name').asString:='Data field #' + IntToStr(mId);
mDataset.post;
end;
showmessage(mDataset.saveToString);
finally
mDataset.free;
end;
end;
Saving a dataset to JSON is now a snap
unit w3dataset;
//#############################################################################
//
// Unit: w3dataset.pas
// Author: Jon Lennart Aasenden
// Copyright: Jon Lennart Aasenden, all rights reserved
//
// Description:
// ============
// Implements a small and fast in-memory dataset. Supports all the basic
// dataset operations (including autoinc field type) but no SQL and
// as of writing, no filtering scheme or regEx support.
//
//
// Cipher Diaz of QUARTEX
//
//#############################################################################
interface
uses
W3System;
{.$DEFINE USE_DEVCODE}
type
(* Forward declaration *)
TW3CustomDatasetField = Class;
TW3BooleanField = Class;
TW3IntegerField = Class;
TW3FloatField = Class;
TW3StringField = Class;
TW3DatasetFields = Class;
TW3CustomDataset = Class;
TW3FieldDef = Class;
TW3FieldDefs = Class;
(* Exception classes *)
EW3FieldDefs = Class(EW3Exception);
EW3DatasetField = Class(EW3Exception);
EW3Dataset = Class(EW3Exception);
TW3DatasetPacket = Variant;
TW3DatasetFieldType =
(
ftUnknown,
ftBoolean,
ftInteger,
ftFloat,
ftString,
ftDateTime,
ftAutoInc, // Calculated
ftGUID // Calculated
);
TW3DatasetState =(dsIdle,dsInsert,dsEdit);
IDatasetFieldsAccess = Interface
Procedure ResetValues;
Procedure setReadOnly(const aValue:Boolean);
end;
IFieldDefAccess = interface
Procedure SetReadOnly(Const aValue:Boolean);
function getFieldIdentifier:String;
end;
TW3GUID = Class
public
class function CreateGUID:String;
end;
TW3CustomDatasetField = Class(TObject)
private
FName: String;
FKind: TW3DatasetFieldType;
FReadOnly: Boolean;
FValue: Variant;
FParent: TW3DatasetFields;
Procedure setAsDateTime(const aValue:TDateTime);
function getAsDateTime:TDateTime;
protected
Procedure Calculate;virtual;
function getCalculated:Boolean;virtual;
function getValue:Variant;virtual;
procedure setValue(const aValue:variant);virtual;
procedure setName (const aValue:String);
procedure setKind (const aKind:TW3DatasetFieldType);
Procedure setReadOnly(const aValue:Boolean);
public
Property Parent:TW3DatasetFields read FParent;
Property Kind:TW3DatasetFieldType read FKind;
Property Name:String read FName write setName;
Property Data:Variant read getValue write setValue;
Property Calculated:Boolean read getCalculated;
Property AsString:String
read (TVariant.AsString(FValue))
write (FValue:=Value);
Property AsInteger:Integer
read (TVariant.asInteger(FValue))
write (FValue:=Value);
Property AsBoolean:Boolean
read (TVariant.AsBool(FValue))
write (FValue:=Value);
Property AsFloat:Float
read (TVariant.asFloat(FValue))
write (FValue:=Value);
Property AsDateTime:TDateTime
read getAsDateTime
write setAsDateTime;
Constructor Create(const aParent:TW3DatasetFields);virtual;
End;
TW3AutoIncField = Class(TW3CustomDatasetField)
private
FCalc: Integer;
protected
Procedure Calculate;override;
function getCalculated:Boolean;override;
public
Property Value:Integer
read (TVariant.AsInteger(Inherited getValue));
End;
TW3GUIDField = Class(TW3CustomDatasetField)
protected
Procedure Calculate;override;
function getCalculated:Boolean;override;
public
Property Value:String
read (TVariant.asString(Inherited getValue));
End;
TW3BooleanField = Class(TW3CustomDatasetField)
public
Property Value:Boolean
read (TVariant.AsBool(Inherited getValue))
write (inherited setValue(Value));
End;
TW3IntegerField = Class(TW3CustomDatasetField)
public
Property Value:Integer
read (TVariant.AsInteger(Inherited getValue))
write (inherited setValue(Value));
end;
TW3FloatField = Class(TW3CustomDatasetField)
public
Property Value:Float
read (TVariant.AsFloat(Inherited getValue))
write (inherited setValue(Value));
end;
TW3StringField = Class(TW3CustomDatasetField)
public
Property Value:String
read (TVariant.AsString(Inherited getValue))
write (inherited setValue(Value));
end;
TW3DateTimeField = Class(TW3CustomDatasetField)
protected
function getValue:TDateTime;reintroduce;
procedure setValue(const aValue:TDateTime);reintroduce;
public
Property Value:TDateTime read getValue write setValue;
End;
TW3DatasetFields = Class(TObject,IDatasetFieldsAccess)
private
FFields: Array of TW3CustomDatasetField;
protected
(* IMPLEMENTS:: IDatasetFieldsAccess *)
Procedure ResetValues;
Procedure setReadOnly(const aValue:Boolean);
public
Property Count:Integer read (FFields.count);
Property Items[index:Integer]:TW3CustomDatasetField read (FFields[index]);
function DataExport:TW3DatasetPacket;virtual;
Procedure DataImport(const aValue:TW3DatasetPacket);virtual;
function IndexOf(aName:String):Integer;
function Add(aName:String;
const aKind:TW3DatasetFieldType):TW3CustomDatasetField;
Procedure DeleteByName(aName:String);
Procedure Delete(const aIndex:Integer);
Procedure Clear;
function FieldByName(aName:String):TW3CustomDatasetField;
Destructor Destroy;Override;
End;
TW3FieldDef = Class(Tobject)
private
FDatatype: TW3DatasetFieldType;
FName: String;
FReadOnly: Boolean;
FParent: TW3FieldDefs;
Procedure setType(const aValue:TW3DatasetFieldType);
Procedure setName(const aName:String);
protected
Procedure setReadOnly(const aValue:Boolean);
public
Property Name:String read FName write setName;
Property Datatype:TW3DatasetFieldType read FDatatype write setType;
Constructor Create(Const aParent:TW3FieldDefs);virtual;
End;
TW3FieldDefs = Class(TObject,IFieldDefAccess)
private
FFields: Array of TW3FieldDef;
FId: Integer;
FReadOnly: Boolean;
protected
function getFieldIdentifier:String;virtual;
Procedure SetReadOnly(Const aValue:Boolean);
public
Property ReadOnly:Boolean read FReadOnly;
Property Fields[index:Integer]:TW3FieldDef
read (FFields[index]);default;
Property Count:Integer read (FFields.Count);
function Add(aName:String;
const aDataType:TW3DatasetFieldType):TW3FieldDef;
function FieldByName(aName:String):TW3FieldDef;
Function IndexOf(aName:String):Integer;
Procedure Delete(const aIndex:Integer);overload;
procedure Delete(const aItem:TW3FieldDef);overload;
function SaveToString:String;
Procedure LoadFromString(const aText:String);
function toString:String;virtual;
Procedure Clear;
Destructor Destroy;Override;
End;
TDatasetStateChangeEvent = Procedure (sender:TObject;const aState:TW3DatasetState);
TDatasetPositionChangeEvent = procedure (sender:TObject;aOldPos,aNewPos:Integer);
TDatasetRecordDeleteEvent = Procedure (sender:TObject;const aRecNo:Integer);
TW3CustomDataset = Class(TObject)
private
FFields: TW3DatasetFields;
FDefs: TW3FieldDefs;
FCache: Array of TW3DatasetPacket;
FState: TW3DatasetState;
FActive: Boolean;
FDestroying:Boolean;
FOnCreated: TNotifyEvent;
FOnClosed: TNotifyEvent;
FOnState: TDatasetStateChangeEvent;
FOnPos: TDatasetPositionChangeEvent;
FOnDelete: TDatasetRecordDeleteEvent;
FDsIndex: Integer;
Procedure UpdateCalculatedFields;
procedure setActive(const aValue:Boolean);
Procedure setPosition(const aNewPosition:Integer);
protected
Procedure DoBeforeDatasetCreated;virtual;
Procedure DoAfterDatasetCreated;virtual;
Procedure DoBeforeDatasetClosed;virtual;
Procedure DoAfterDatasetClosed;virtual;
function getRecCount:Integer;virtual;
function getRecNo:Integer;virtual;
function getEOF:Boolean;virtual;
function getBOF:Boolean;virtual;
procedure getPacketToFields;virtual;
Procedure setPacketFromFields;virtual;
procedure setState(const aState:TW3DatasetState);
public
Property Active:Boolean read FActive write setActive;
Property State:TW3DatasetState read FState;
Property Fields:TW3DatasetFields read FFields;
Property FieldDefs:TW3FieldDefs
read FDefs;
Property EOF:Boolean read getEOF;
Property BOF:Boolean read getBOF;
Property Count:Integer read getRecCount;
Property RecNo:Integer read getRecNo;
// Save and Load to JSON format
function SaveToString:String;
Procedure LoadFromString(Const aText:String);
Procedure Append; //Add record LAST always
procedure Insert; //Add record at position
Procedure Delete; //Delete record at position
Procedure Post; //Complete insertion or update
procedure Edit; //Edit record at position
Procedure Next; //Navigate 1 step forward
Procedure Back; //Navigate 1 step back
Procedure First; //Navigate to first record
Procedure Last; //Navigate to last record
Procedure MoveTo(const aRecNo:Integer); //Navigate directly
Procedure CreateDataset;
Procedure Close;
Procedure Cancel;
class function Version:String;
Constructor Create;virtual;
Destructor Destroy;Override;
published
Property OnRecordDeleted:TDatasetRecordDeleteEvent
read FOnDelete write FOnDelete;
Property OnDatasetCreated:TNotifyEvent read FOnCreated write FOnCreated;
Property OnDatasetClosed:TNotifyevent read FOnClosed write FOnClosed;
Property OnStateChanged:TDatasetStateChangeEvent
read FOnState write FOnState;
Property OnPositionChanged:TDatasetPositionChangeEvent
read FOnPos write FOnPos;
end;
{$IFDEF USE_DEVCODE}
TW3MemoryDataset = class(TW3CustomDataset)
private
FCache: Array of TW3DatasetPacket;
protected
procedure getPacketToFields;override;
Procedure setPacketFromFields;override;
function getRecCount:Integer;override;
Procedure DoBeforeDatasetClosed;override;
End;
{$ENDIF}
TW3DataSource = Class(TObject)
end;
implementation
const
CNT_DATASET_MAJOR = 0;
CNT_DATASET_MINOR = 1;
resourcestring
CNT_DATASET_FIELD_READONLY = 'Failed to alter value, field is read-only error';
CNT_DATASET_NOT_ACTIVE = 'Operation failed, dataset is not active error';
CNT_DATASET_INVALID_STATE = 'Invalid state for operation error';
CNT_DATASET_FIELD_UNKNOWN = 'Failed to match field class for datatype error';
CNT_DATASET_FIELDEF_LIVE = 'Field definition cannot be altered in a live dataset error';
//#############################################################################
// Internal records used for storage etc.
//#############################################################################
type
TW3FieldDefData = Record
fdName: String;
fdDatatype: TW3DatasetFieldType;
End;
TW3FieldDefHeader = Record
ddMagic: Integer;
ddDefs: Array of TW3FieldDefData;
End;
TW3DatasetHeader = Record
dhMagic: Integer;
dhCount: Integer;
dhFieldDefs: String;
dhData: String;
End;
//#############################################################################
// TW3GUID
//#############################################################################
// http://www.ietf.org/rfc/rfc4122.txt
class function TW3GUID.CreateGUID:String;
Begin
asm
var s = [];
var hexDigits = "0123456789abcdef";
for (var i = 0; i < 36; i++) {
s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
}
s[14] = "4";
s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1);
s[8] = s[13] = s[18] = s[23] = "-";
@result = s.join("");
end;
result:=uppercase(result);
end;
//#############################################################################
// TW3MemoryDataset
//#############################################################################
{$IFDEF USE_DEVCODE}
procedure TW3MemoryDataset.getPacketToFields;
Begin
if (RecNo>=0) and (RecNo<FCache.Length) then
Fields.DataImport(FCache[RecNo]);
end;
Procedure TW3MemoryDataset.setPacketFromFields;
Begin
if (RecNo>=0) and (RecNo<FCache.Length) then
FCache[RecNo]:=Fields.DataExport;
end;
function TW3MemoryDataset.getRecCount:Integer;
Begin
result:=FCache.Count;
end;
Procedure TW3MemoryDataset.DoBeforeDatasetClosed;
Begin
FCache.Clear;
inherited;
end;
{$ENDIF}
//#############################################################################
// TW3FieldDefs
//#############################################################################
Destructor TW3FieldDefs.Destroy;
begin
if FFields.Count>0 then
Clear;
inherited;
end;
Procedure TW3FieldDefs.clear;
var
x: Integer;
begin
if FFields.Count>0 then
Begin
try
for x:=FFields.low to FFields.high do
FFields[x].free;
finally
FFields.clear;
end;
end;
end;
function TW3FieldDefs.getFieldIdentifier:String;
Begin
repeat
inc(FId);
result:='Field' + FId.toString;
until IndexOf(result)<0;
end;
Procedure TW3FieldDefs.SetReadOnly(Const aValue:Boolean);
var
mItem: TW3FieldDef;
Begin
FReadOnly:=aValue;
if FFields.length>0 then
for mItem in FFields do
mItem.setReadOnly(aValue);
end;
function TW3FieldDefs.Add(aName:String;
const aDataType:TW3DatasetFieldType):TW3FieldDef;
Begin
result:=NIL;
if not FReadOnly then
begin
aName:=trim(lowercase(aName));
if aName.length>0 then
Begin
if indexOf(aName)<0 then
Begin
result:=TW3FieldDef.Create(self);
result.name:=aName;
result.datatype:=aDataType;
FFields.add(result);
end else
raise EW3FieldDefs.Create('A field with that name already exists error');
end else
raise EW3FieldDefs.create('Failed to add field definition, invalid name error');
end else
raise EW3FieldDefs.create(CNT_DATASET_FIELDEF_LIVE);
end;
function TW3FieldDefs.FieldByName(aName:String):TW3FieldDef;
var
x: Integer;
Begin
result:=NIL;
if FFields.Length>0 then
begin
aName:=lowercase(trim(aName));
if length(aName)>0 then
begin
for x:=FFields.low to FFields.high do
Begin
if aName = lowercase(FFields[x].name) then
begin
result:=FFields[x];
break;
end;
end;
end;
end;
end;
Function TW3FieldDefs.IndexOf(aName:String):Integer;
var
x: Integer;
Begin
result:=-1;
if FFields.Length>0 then
begin
aName:=lowercase(trim(aName));
if length(aName)>0 then
begin
for x:=FFields.low to FFields.high do
Begin
if aName = lowercase(FFields[x].name) then
begin
result:=x;
break;
end;
end;
end;
end;
end;
Procedure TW3FieldDefs.Delete(const aIndex:Integer);
Begin
if not FReadOnly then
begin
If (aIndex>=0) and (aIndex<FFields.length) then
Begin
FFields[aIndex].free;
FFields.Delete(aIndex,1);
end;
end else
raise EW3FieldDefs.create(CNT_DATASET_FIELDEF_LIVE);
end;
procedure TW3FieldDefs.Delete(const aItem:TW3FieldDef);
Begin
if aItem<>NIL then
Delete(IndexOf(aItem.Name)) else
raise EW3FieldDefs.create('Delete operation failed, reference was NIL error');
end;
function TW3FieldDefs.SaveToString:String;
var
x: Integer;
mHead: TW3FieldDefHeader;
Begin
mHead.ddMagic:=$BABE;
if FFields.Count>0 then
Begin
mHead.ddDefs.SetLength(FFields.Count);
for x:=FFields.low to FFields.high do
Begin
mHead.ddDefs[x].fdDatatype:=FFields[x].dataType;
mHead.ddDefs[x].fdName:=FFields[x].Name;
end;
end;
asm
@result = JSON.stringify(@mHead);
end;
end;
Procedure TW3FieldDefs.LoadFromString(Const aText:String);
var
mHead: TW3FieldDefHeader;
x: Integer;
Begin
Clear;
try
asm
@mHead = JSON.parse(@aText);
end;
except
On e: exception do
Raise EW3FieldDefs.CreateFmt
('Failed to load field-definitions, system threw exception: %s',[e.message]);
end;
if mHead.ddMagic=$BABE then
Begin
if mHead.ddDefs.count>0 then
begin
for x:=mHead.ddDefs.low to mHead.ddDefs.high do
Add(mHead.ddDefs[x].fdName,mHead.ddDefs[x].fdDatatype);
end;
end else
Raise EW3FieldDefs.Create('Failed to load field-definitions, invalid header signature error');
end;
function TW3FieldDefs.toString:String;
var
x: Integer;
Begin
if FFields.Count>0 then
Begin
for x:=FFields.low to FFields.high do
Begin
result+='Name=' + '"' + FFields[x].Name + '"' + ' Datatype=';
case FFields[x].Datatype of
ftUnknown: result+='Unknown';
ftBoolean: result+='Boolean';
ftInteger: result+='Integer';
ftFloat: result+='Float';
ftString: result+='String';
ftDateTime: result+='DateTime';
ftAutoInc: result+='AutoInc';
ftGUID: result+='GUID';
end;
result:=result + #13;
end;
end;
end;
//#############################################################################
// TW3FieldDef
//#############################################################################
Constructor TW3FieldDef.Create(Const aParent:TW3FieldDefs);
Begin
inherited Create;
if aParent<>NIL then
begin
FParent:=aParent;
FName:=(FParent as IFieldDefAccess).getFieldIdentifier;
end;
end;
Procedure TW3FieldDef.setReadOnly(const aValue:Boolean);
Begin
FReadOnly:=aValue;
end;
Procedure TW3FieldDef.setType(const aValue:TW3DatasetFieldType);
begin
if not FReadOnly then
FDatatype:=aValue;
end;
Procedure TW3FieldDef.setName(const aName:String);
Begin
if not FReadOnly then
Begin
FName:=aName;
end;
end;
//#############################################################################
// TW3CustomDataset
//#############################################################################
Constructor TW3CustomDataset.Create;
Begin
inherited Create;
FFields:=TW3DatasetFields.Create;
FDefs:=TW3FieldDefs.Create;
FState:=dsIdle;
FDestroying:=False;
FDsIndex:=-1;
end;
Destructor TW3CustomDataset.Destroy;
Begin
FDestroying:=true;
if FActive then
Close;
FFields.free;
FDefs.free;
inherited;
end;
Class function TW3CustomDataset.Version:String;
Begin
result:=IntToStr(CNT_DATASET_MAJOR) + '.' + IntToStr(CNT_DATASET_MINOR);
end;
Function TW3CustomDataset.saveToString:String;
var
mHead: TW3DatasetHeader;
Begin
if FActive then
Begin
try
(* Setup the header *)
mHead.dhMagic:=$CAFE;
mHead.dhCount:=getRecCount;
(* Serialize and store field-defs *)
mHead.dhFieldDefs:=EncodeURI(FDefs.SaveToString);
(* Serialize and store dataset records *)
asm
(@mHead).dhData = JSON.stringify((@self).FCache);
end;
(* Now serialize and return text representation of data structure *)
asm
@result = JSON.stringify(@mHead);
end;
except
on e: exception do
raise EW3Dataset.CreateFmt
('Failed to store dataset, system threw exception: %s',[e.message]);
end;
end;
end;
Procedure TW3CustomDataset.LoadFromString(Const aText:String);
var
mHead: TW3DatasetHeader;
Begin
(* If the dataset is active, close it down *)
if FActive then
Close;
(* Check source string *)
if aText.Length>0 then
Begin
(* Attempt to de-serialize JSON data *)
try
asm
@mHead = JSON.parse(@aText);
end;
except
on e: exception do
Raise EW3Dataset.CreateFmt
('Failed to load dataset, system threw exception: %s',[e.message]);
end;
(* Verify header *)
if mHead.dhMagic=$CAFE then
Begin
(* Load DEFS if any *)
if mHead.dhFieldDefs.Length>0 then
FDefs.LoadFromString(DecodeURI(mHead.dhFieldDefs));
(* Any actual rows? ok, try to load them *)
if mHead.dhCount>0 then
Begin
try
asm
(@self).FCache = JSON.parse((@mHead).dhData);
end;
except
on e: exception do
Raise EW3Dataset.CreateFmt
('Failed to load dataset, system threw exception: %s',[e.message]);
end;
end;
end else
Raise EW3Dataset.Create('Failed to load dataset, invalid header signature error');
end else
Raise EW3Dataset.Create('Failed to load dataset, string was empty error');
end;
Procedure TW3CustomDataset.CreateDataset;
Procedure SetupFields;
var
x: Integer;
begin
for x:=0 to FDefs.Count-1 do
FFields.add(FDefs[x].Name,FDefs[x].Datatype);
end;
Begin
if not FActive then
Begin
if FDefs.Count>0 then
Begin
(* Clear any fields if the user has added some.
All fields are created from filed-defs *)
FFields.Clear;
DoBeforeDatasetCreated;
try
FActive:=True;
setState(dsIdle);
setPosition(-1);
(* Import table schema to field construct *)
SetupFields;
(* Lock fields & defs, read/write access to defined
structure only. No alteration while the dataset
is "live" *)
(FFields as IDatasetFieldsAccess).setReadOnly(true);
(FDefs as IFieldDefAccess).setReadOnly(true);
finally
DoAfterDatasetCreated;
end;
end else
Raise EW3Dataset.Create('No field definitions for dataset error');
end;
end;
Procedure TW3CustomDataset.Close;
begin
if FActive then
Begin
DoBeforeDatasetClosed;
try
try
FFields.Clear;
FCache.Clear;
finally
FActive:=False;
FState:=dsIdle;
FDsIndex:=-1;
(FFields as IDatasetFieldsAccess).resetValues;
(FFields as IDatasetFieldsAccess).setReadOnly(False);
(FDefs as IFieldDefAccess).setReadOnly(False);
end;
finally
DoAfterDatasetClosed;
end;
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
procedure TW3CustomDataset.setState(const aState:TW3DatasetState);
Begin
FState:=aState;
if assigned(FOnState) then
FOnState(self,aState);
end;
Procedure TW3CustomDataset.getPacketToFields;
Begin
if (FdsIndex>=0) and (FdsIndex<FCache.Length) then
FFields.DataImport(FCache[FdsIndex]);
end;
Procedure TW3CustomDataset.setPacketFromFields;
Begin
if (FdsIndex>=0) and (FdsIndex<FCache.Length) then
FCache[FDsIndex]:=FFields.DataExport;
end;
Procedure TW3CustomDataset.setPosition(const aNewPosition:Integer);
var
mOld: Integer;
Begin
if aNewPosition<>FdsIndex then
begin
mOld:=FdsIndex;
FDsIndex:=aNewPosition;
if not (FState=dsInsert) then
Begin
if (FdsIndex>=0)
and (FdsIndex<getRecCount) then
getPacketToFields;
end;
if assigned(FOnPos) then
FOnPos(self,mOld,aNewPosition);
end;
end;
procedure TW3CustomDataset.setActive(const aValue:Boolean);
Begin
if aValue<>FActive then
begin
Case aValue of
true: CreateDataset;
false: Close;
end;
end;
end;
Procedure TW3CustomDataset.UpdateCalculatedFields;
var
x: Integer;
Begin
for x:=0 to FFields.Count-1 do
if FFields.Items[x].calculated then
FFields.items[x].Calculate;
end;
Procedure TW3CustomDataset.Append;
Begin
if FActive then
Begin
if FState=dsIdle then
Begin
//Actual items + 1
self.setPosition(FCache.Count);
//Last;
setState(dsInsert);
(FFields as IDatasetFieldsAccess).resetValues;
UpdateCalculatedFields;
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
procedure TW3CustomDataset.Insert;
Begin
if FActive then
Begin
if FState=dsIdle then
Begin
if (RecNo<0) then
setPosition(FCache.Count);
setState(dsInsert);
(FFields as IDatasetFieldsAccess).resetValues;
UpdateCalculatedFields;
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
procedure TW3CustomDataset.Edit;
Begin
if FActive then
Begin
if FState=dsIdle then
Begin
if FCache.Length>0 then
Begin
if (FdsIndex=-1) then
self.setPosition(0) else
if (FdsIndex=FCache.length) then
setPosition(FCache.length-1);
setState(dsEdit);
UpdateCalculatedFields;
end;
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Delete;
Begin
if FActive then
Begin
if FState=dsIdle then
begin
if Count>0 then
Begin
if (FdsIndex>=0) and (FdsIndex<FCache.count) then
Begin
(* Signal satan that his work is done *)
if assigned(FOnDelete) then
FOnDelete(self,FdsIndex);
(* Delete record *)
FCache.Delete(FdsIndex,1);
(* Misaligned recno? Backtrack. This will fall back to -1,
which is BOF, when the last record is deleted *)
if FdsIndex>=FCache.Count then
FdsIndex:=FCache.Count-1;
end else
raise EW3Dataset.CreateFmt('Delete failed, misaligned RecNo [%s]',[FdsIndex]);
end else
Raise EW3Dataset.Create('Delete failed, dataset is empty error');
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Cancel;
Begin
if FActive then
begin
if (FState=dsInsert)
or (FState=dsEdit) then
begin
setState(dsIdle);
(FFields as IDatasetFieldsAccess).resetValues;
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Post;
var
mDummy: TW3DatasetPacket;
Begin
if FActive then
Begin
Case FState of
dsInsert:
Begin
(* Grow the internal cache *)
if FdsIndex=getRecCount then
Begin
(* Insert at end of Dataset (a.k.a "Append") *)
FCache.Add(mDummy);
FdsIndex:=FCache.Length-1;
end else
(* insert "directly" at position *)
FCache.Insert(FDsIndex,mDummy);
(* Write data to record pointer *)
setPacketFromFields;
(* position record PTR on last record *)
//setPosition(FCache.Count-1);
(* set state to idle *)
setState(dsIdle);
end;
dsEdit:
begin
setPacketFromFields;
setState(dsIdle);
end;
else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end;
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.First;
var
mpos: Integer;
Begin
if FActive then
begin
if FState=dsIdle then
Begin
if getRecCount>0 then
mPos:=0 else
mpos:=-1;
setPosition(mPos);
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Last;
var
mpos: Integer;
Begin
if FActive then
begin
if FState=dsIdle then
Begin
if getRecCount>0 then
mPos:=getRecCount-1 else
mpos:=-1;
setPosition(mPos);
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Next;
Begin
if FActive then
Begin
if FState=dsIdle then
setPosition(TInteger.EnsureRange(FDsIndex+1,-1,getRecCount)) else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Back;
Begin
if FActive then
Begin
if FState=dsIdle then
setPosition(TInteger.EnsureRange(FDsIndex+1,-1,getRecCount)) else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.MoveTo(const aRecNo:Integer);
Begin
if FActive then
Begin
if FState=dsIdle then
setPosition(TInteger.EnsureRange(aRecNo,0,getRecCount-1)) else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.DoBeforeDatasetCreated;
Begin
end;
Procedure TW3CustomDataset.DoAfterDatasetCreated;
Begin
if assigned(FOnCreated) then
Begin
if not FDestroying then
FOnCreated(self);
end;
end;
Procedure TW3CustomDataset.DoBeforeDatasetClosed;
Begin
end;
Procedure TW3CustomDataset.DoAfterDatasetClosed;
Begin
if assigned(FOnClosed) then
Begin
if not FDestroying then
FOnClosed(self);
end;
end;
function TW3CustomDataset.getRecCount:Integer;
Begin
result:=FCache.Count;
end;
function TW3CustomDataset.getRecNo:Integer;
Begin
if FActive then
result:=FDsIndex else
result:=-1;
end;
function TW3CustomDataset.getEOF:Boolean;
Begin
if FActive then
result:=FDsIndex>=getRecCount else
result:=True;
end;
function TW3CustomDataset.getBOF:Boolean;
Begin
if FActive then
result:=FDsIndex<=0 else
result:=True;
end;
//#############################################################################
// TW3DatasetFields
//#############################################################################
Destructor TW3DatasetFields.Destroy;
Begin
Clear;
inherited;
end;
Procedure TW3DatasetFields.setReadOnly(const aValue:Boolean);
var
x: Integer;
begin
if FFields.Length>0 then
Begin
for x:=FFields.Low to FFields.High do
FFields[x].setReadOnly(aValue);
end;
end;
Procedure TW3DatasetFields.ResetValues;
var
mItem: TW3CustomDatasetField;
Begin
if FFields.Length>0 then
Begin
for mItem in FFields do
mItem.setValue(null);
end;
end;
Procedure TW3DatasetFields.Clear;
var
x: Integer;
Begin
if FFields.Count>0 then
Begin
try
for x:=FFields.Low to FFields.High do
FFields[x].free;
finally
FFields.Clear;
end;
end;
end;
Procedure TW3DatasetFields.DeleteByName(aName:String);
var
mIndex: Integer;
Begin
mIndex:=IndexOf(aName);
if mIndex>=0 then
Begin
FFields[mIndex].free;
FFields.Delete(mIndex,1);
end;
end;
Procedure TW3DatasetFields.Delete(const aIndex:Integer);
Begin
if (aIndex>=0) and (aIndex<FFields.Count) then
Begin
FFields[aIndex].free;
FFields.Delete(aIndex,1);
end;
end;
function TW3DatasetFields.Add(aName:String;
const aKind:TW3DatasetFieldType):TW3CustomDatasetField;
Begin
result:=NIL;
aName:=lowercase(trim(aName));
if aName.Length>0 then
Begin
if IndexOf(aName)=-1 then
Begin
case aKind of
ftBoolean: result:=TW3BooleanField.Create(self);
ftInteger: result:=TW3IntegerField.Create(self);
ftFloat: result:=TW3FloatField.Create(self);
ftString: result:=TW3StringField.Create(self);
ftDateTime: result:=TW3DateTimeField.Create(self);
ftAutoInc: result:=TW3AutoIncField.Create(self);
ftGUID: result:=TW3GUIDField.Create(self);
else result:=NIL;
end;
if result<>NIL then
Begin
result.Name:=aName;
FFields.add(result);
end else
Raise EW3DatasetField.Create(CNT_DATASET_FIELD_UNKNOWN);
end;
end;
end;
function TW3DatasetFields.DataExport:TW3DatasetPacket;
var
x: Integer;
mField:TW3CustomDatasetField;
Begin
result:=TVariant.CreateObject;
if FFields.count>0 then
Begin
for mField in FFields do
result[mField.Name]:=mField.getValue;
end;
end;
Procedure TW3DatasetFields.DataImport(const aValue:TW3DatasetPacket);
var
mField:TW3CustomDatasetField;
Begin
if FFields.count>0 then
Begin
for mField in FFields do
mField.setvalue(aValue[mField.Name]);
end;
end;
function TW3DatasetFields.IndexOf(aName:String):Integer;
var
x: Integer;
Begin
result:=-1;
aName:=lowercase(trim(aName));
if aName.Length>0 then
Begin
for x:=FFields.Low to FFIelds.High do
Begin
If FFIelds[x].Name=aName then
Begin
result:=x;
break;
end;
end;
end;
end;
function TW3DatasetFields.FieldByName(aName:String):TW3CustomDatasetField;
var
x: Integer;
Begin
result:=NIL;
aName:=lowercase(trim(aName));
if aName.Length>0 then
Begin
for x:=FFields.Low to FFields.High do
Begin
If FFields[x].Name=aName then
Begin
result:=FFields[x];
break;
end;
end;
end;
end;
//#############################################################################
// TW3GUIDField
//#############################################################################
function TW3GUIDField.getCalculated:Boolean;
Begin
result:=true;
end;
Procedure TW3GUIDField.Calculate;
Begin
inherited setValue(uppercase(TW3GUID.createGUID));
end;
//#############################################################################
// TW3AutoIncField
//#############################################################################
function TW3AutoIncField.getCalculated:Boolean;
Begin
result:=true;
end;
Procedure TW3AutoIncField.Calculate;
Begin
inc(FCalc);
inherited setValue(FCalc);
end;
//#############################################################################
// TW3DateTimeField
//#############################################################################
function TW3DateTimeField.getValue:TDateTime;
Begin
result:=inherited getValue;
end;
procedure TW3DateTimeField.setValue(const aValue:TDateTime);
Begin
inherited setValue(aValue);
end;
//#############################################################################
// TW3CustomDatasetField
//#############################################################################
Constructor TW3CustomDatasetField.Create(const aParent:TW3DatasetFields);
Begin
inherited Create;
FParent:=aParent;
FKind:=ftUnknown;
FName:='Field' + IntToStr( w3_GetUniqueNumber );
end;
Procedure TW3CustomDatasetField.setAsDateTime(const aValue:TDateTime);
Begin
FValue:=aValue;
end;
function TW3CustomDatasetField.getAsDateTime:TDateTime;
Begin
result:=FValue;
end;
Procedure TW3CustomDatasetField.Calculate;
Begin
end;
function TW3CustomDatasetField.getCalculated:Boolean;
Begin
result:=False;
end;
function TW3CustomDatasetField.getValue:Variant;
Begin
result:=FValue;
end;
procedure TW3CustomDatasetField.setValue(const aValue:variant);
Begin
FValue:=aValue;
end;
procedure TW3CustomDatasetField.setName(const aValue:String);
Begin
if not FReadOnly then
FName:=lowercase(trim(aValue)) else
Raise EW3DatasetField.Create(CNT_DATASET_FIELD_READONLY);
end;
procedure TW3CustomDatasetField.setKind(const aKind:TW3DatasetFieldType);
Begin
if not FReadOnly then
FKind:=aKind else
Raise EW3DatasetField.Create(CNT_DATASET_FIELD_READONLY);
end;
Procedure TW3CustomDatasetField.setReadOnly(const aValue:Boolean);
Begin
FReadOnly:=aValue;
end;
end.
Dataset for Smart Mobile Studio
I’ve only had a couple of hours to work on this, but here is the first incarnation of TDataset for Smart Mobile Studio. It will need some work (and a lot of testing) before it’s released into the wild – so feel free to play around with it, but dont use it in production level projects just yet.
Notice the heavy use of Property Expressions, a unique feature of Smart Pascal. Especially in the field classes, where property expressions remove the need for at least 2 getter/setter methods. Fast, elegant and very pleasant to write.
Using the dataset
Fairly straight forward stuff. Here is how you create a dataset:
FDataset.Fields.Add('id',ftInteger);
FDataset.Fields.add('name',ftString);
FDataset.CreateDataset;
And you insert data in much the same way as under Delphi:
for x:=0 to 50 do
Begin
FDataset.Insert;
FDataset.fields.fieldByName('id').asInteger:=x+1;
FDataset.Fields.FieldByName('name').asString:='this is String #' + x.ToString;
FDataset.Post;
end;
And you also edit stuff in much the same way as you would in Delphi or Lazarus:
FDataset.first;
FDataset.edit;
FDataset.Fields.FieldByName('name').asString:='We altered this one!';
FDataset.post;
And last but not least, navigation should be en-par with what you are used to:
FDataset.first;
repeat
writeln(FDataset.Fields.FieldByName('name').asString);
FDataset.next;
until FDataset.EOF;
Note: The data is stored in the FCache array, to export the data, just use JSON to export it – and voila, you can now use datasets to deal with in-app orders, posts, news or whatever. When updating a real database, send the whole dataset as a packet — easy as apple pie 🙂
JSON representation of the data
A simple “Save” routine would look something like this:
Function TW3CustomDataset.saveToString:String;
Begin
asm
@result = JSON.stringify((@self).FCache);
end;
end;
Well, enjoy!
unit w3dataset;
//Copyright Jon Lennart Aasenden, All right reserved.
interface
uses
W3System;
type
TW3CustomDatasetField = Class;
TW3BooleanField = Class;
TW3IntegerField = Class;
TW3FloatField = Class;
TW3StringField = Class;
TW3DatasetFields = Class;
TW3CustomDataset = Class;
EW3DatasetField = Class(EW3Exception);
EW3Dataset = Class(EW3Exception);
TW3DatasetPacket = Variant;
TW3DatasetFieldType =
(
ftUnknown,
ftBoolean,
ftInteger,
ftFloat,
ftString,
ftDateTime
);
IDatasetFieldsAccess = Interface
Procedure ResetValues;
Procedure setReadOnly(const aValue:Boolean);
Function ExportDefs:String;
Procedure ImportDefs(const aDefs:String);
end;
TW3CustomDatasetField = Class(TObject)
private
FName: String;
FKind: TW3DatasetFieldType;
FReadOnly: Boolean;
FValue: Variant;
FParent: TW3DatasetFields;
Procedure setAsDateTime(const aValue:TDateTime);
function getAsDateTime:TDateTime;
protected
function getValue:Variant;virtual;
procedure setValue(const aValue:variant);virtual;
procedure setName (const aValue:String);
procedure setKind (const aKind:TW3DatasetFieldType);
Procedure setReadOnly(const aValue:Boolean);
public
Property Parent:TW3DatasetFields read FParent;
Property Kind:TW3DatasetFieldType read FKind;
Property Name:String read FName write setName;
Property Value:Variant read FValue write FValue;
Property AsString:String
read (TVariant.AsString(FValue))
write (FValue:=Value);
Property AsInteger:Integer
read (TVariant.asInteger(FValue))
write (FValue:=Value);
Property AsBoolean:Boolean
read (TVariant.AsBool(FValue))
write (FValue:=Value);
Property AsFloat:Float
read (TVariant.asFloat(FValue))
write (FValue:=Value);
Property AsDateTime:TDateTime
read getAsDateTime
write setAsDateTime;
Constructor Create(const aParent:TW3DatasetFields);virtual;
End;
TW3BooleanField = Class(TW3CustomDatasetField)
public
Property Value:Boolean
read (TVariant.AsBool(Inherited getValue))
write (inherited setValue(Value));
End;
TW3IntegerField = Class(TW3CustomDatasetField)
public
Property Value:Integer
read (TVariant.AsInteger(Inherited getValue))
write (inherited setValue(Value));
end;
TW3FloatField = Class(TW3CustomDatasetField)
public
Property Value:Float
read (TVariant.AsFloat(Inherited getValue))
write (inherited setValue(Value));
end;
TW3StringField = Class(TW3CustomDatasetField)
public
Property Value:String
read (TVariant.AsString(Inherited getValue))
write (inherited setValue(Value));
end;
TW3DateTimeField = Class(TW3CustomDatasetField)
protected
function getValue:TDateTime;reintroduce;
procedure setValue(const aValue:TDateTime);reintroduce;
public
Property Value:TDateTime read getValue write setValue;
End;
TW3DatasetFields = Class(TObject,IDatasetFieldsAccess)
private
FFields: Array of TW3CustomDatasetField;
protected
(* IMPLEMENTS:: IDatasetFieldsAccess *)
Procedure ResetValues;
Procedure setReadOnly(const aValue:Boolean);
Function ExportDefs:String;virtual;
Procedure ImportDefs(const aDefs:String);virtual;
public
Property Count:Integer read (FFields.count);
Property Items[index:Integer]:TW3CustomDatasetField read (FFields[index]);
function DataExport:TW3DatasetPacket;virtual;
Procedure DataImport(const aValue:TW3DatasetPacket);virtual;
function IndexOf(aName:String):Integer;
function Add(aName:String;
const aKind:TW3DatasetFieldType):TW3CustomDatasetField;
Procedure DeleteByName(aName:String);
Procedure Delete(const aIndex:Integer);
Procedure Clear;
function FieldByName(aName:String):TW3CustomDatasetField;
Destructor Destroy;Override;
End;
TW3DatasetState =(dsIdle,dsInsert,dsEdit);
TDatasetStateChangeEvent = Procedure (sender:TObject;aState:TW3DatasetState);
TDatasetPositionChangeEvent = procedure (sender:TObject;aOldPos,aNewPos:Integer);
TW3CustomDataset = Class(TObject)
private
FFields: TW3DatasetFields;
FCache: Array of TW3DatasetPacket;
FState: TW3DatasetState;
FActive: Boolean;
FDestroying:Boolean;
FOnCreated: TNotifyEvent;
FOnClosed: TNotifyEvent;
FOnState: TDatasetStateChangeEvent;
FOnPos: TDatasetPositionChangeEvent;
FDsIndex: Integer;
procedure setActive(const aValue:Boolean);
Procedure setPosition(const aNewPosition:Integer);
protected
Procedure DoBeforeDatasetCreated;virtual;
Procedure DoAfterDatasetCreated;virtual;
Procedure DoBeforeDatasetClosed;virtual;
Procedure DoAfterDatasetClosed;virtual;
function getRecCount:Integer;virtual;
function getRecNo:Integer;virtual;
function getEOF:Boolean;virtual;
function getBOF:Boolean;virtual;
procedure getPacketToFields;virtual;
Procedure setPacketFromFields;virtual;
procedure setState(const aState:TW3DatasetState);
public
Property Active:Boolean read FActive write setActive;
Property State:TW3DatasetState read FState;
Property Fields:TW3DatasetFields read FFields;
Property EOF:Boolean read getEOF;
Property BOF:Boolean read getBOF;
Property Count:Integer read getRecCount;
Property RecNo:Integer read getRecNo;
procedure Insert;
Procedure Delete;
Procedure Post;
procedure Edit;
Procedure Next;
Procedure Back;
Procedure First;
Procedure Last;
Procedure CreateDataset;
Procedure Close;
Procedure Cancel;
Constructor Create;virtual;
Destructor Destroy;Override;
published
Property OnDatasetCreated:TNotifyEvent read FOnCreated write FOnCreated;
Property OnDatasetClosed:TNotifyevent read FOnClosed write FOnClosed;
Property OnStateChanged:TDatasetStateChangeEvent
read FOnState write FOnState;
Property OnPositionChanged:TDatasetPositionChangeEvent
read FOnPos write FOnPos;
end;
TW3Dataset = class(TW3CustomDataset)
End;
TW3DataSource = Class(TObject)
end;
implementation
resourcestring
CNT_DATASET_FIELD_READONLY = 'Failed to alter value, field is read-only error';
CNT_DATASET_NOT_ACTIVE = 'Operation failed, dataset is not active error';
CNT_DATASET_INVALID_STATE = 'Invalid state for operation error';
//#############################################################################
// TW3CustomDataset
//#############################################################################
Constructor TW3CustomDataset.Create;
Begin
inherited Create;
FFields:=TW3DatasetFields.Create;
FState:=dsIdle;
FDestroying:=False;
FDsIndex:=-1;
end;
Destructor TW3CustomDataset.Destroy;
Begin
FDestroying:=true;
if FActive then
Close;
FFields.free;
inherited;
end;
Procedure TW3CustomDataset.Close;
begin
if FActive then
Begin
DoBeforeDatasetClosed;
try
try
FFields.Clear;
FCache.Clear;
finally
FActive:=False;
FState:=dsIdle;
FDsIndex:=-1;
(FFields as IDatasetFieldsAccess).resetValues;
end;
finally
DoAfterDatasetClosed;
end;
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
procedure TW3CustomDataset.setState(const aState:TW3DatasetState);
Begin
FState:=aState;
if assigned(FOnState) then
FOnState(self,aState);
end;
Procedure TW3CustomDataset.getPacketToFields;
Begin
if (FdsIndex>=0) and (FdsIndex<FCache.Length) then
FFields.DataImport(FCache[FdsIndex]);
end;
Procedure TW3CustomDataset.setPacketFromFields;
Begin
if (FdsIndex>=0) and (FdsIndex<FCache.Length) then
FCache[FDsIndex]:=FFields.DataExport;
end;
Procedure TW3CustomDataset.setPosition(const aNewPosition:Integer);
var
mOld: Integer;
Begin
if aNewPosition<>FdsIndex then
begin
mOld:=FdsIndex;
FDsIndex:=aNewPosition;
if (FdsIndex>=0)
and (FdsIndex<FCache.Length) then
self.getPacketToFields else
//FFields.DataImport(FCache[FdsIndex]) else
(FFields as IDatasetFieldsAccess).resetValues;
if assigned(FOnPos) then
FOnPos(self,mOld,aNewPosition);
end;
end;
Procedure TW3CustomDataset.CreateDataset;
Begin
if not FActive then
Begin
if FFields.Count>0 then
Begin
DoBeforeDatasetCreated;
try
FActive:=True;
setState(dsIdle);
setPosition(-1);
finally
DoAfterDatasetCreated;
end;
end else
Raise EW3Dataset.Create('No fields defined for dataset error');
end;
end;
procedure TW3CustomDataset.setActive(const aValue:Boolean);
Begin
if aValue<>FActive then
begin
Case aValue of
true: CreateDataset;
false: Close;
end;
end;
end;
procedure TW3CustomDataset.Insert;
Begin
if FActive then
Begin
if FState=dsIdle then
Begin
Last;
setState(dsInsert);
(FFields as IDatasetFieldsAccess).resetValues;
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Delete;
Begin
end;
Procedure TW3CustomDataset.Cancel;
Begin
if FActive then
begin
if (FState=dsInsert)
or (FState=dsEdit) then
begin
setState(dsIdle);
(FFields as IDatasetFieldsAccess).resetValues;
end;
end;
end;
Procedure TW3CustomDataset.Post;
var
mDummy: TW3DatasetPacket;
Begin
if FActive then
Begin
Case FState of
dsInsert:
Begin
(* Grow the internal cache *)
FCache.Add(mDummy);
FdsIndex:=FCache.Length-1;
setPacketFromFields;
(* position record PTR on last record *)
setPosition(FFields.Count-1);
(* set state to idle *)
setState(dsIdle);
end;
dsEdit:
begin
setPacketFromFields;
setState(dsIdle);
end;
else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end;
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
procedure TW3CustomDataset.Edit;
Begin
if FActive then
Begin
if FState=dsIdle then
Begin
if FCache.Length>0 then
Begin
if (FdsIndex=-1) then
self.setPosition(0) else
if (FdsIndex=FCache.length) then
setPosition(FCache.length-1);
setState(dsEdit);
end;
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.First;
var
mpos: Integer;
Begin
if FActive then
begin
if FState=dsIdle then
Begin
if FCache.Length>0 then
mPos:=0 else
mpos:=-1;
setPosition(mPos);
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Last;
var
mpos: Integer;
Begin
if FActive then
begin
if FState=dsIdle then
Begin
if FCache.Length>0 then
mPos:=FCache.Length-1 else
mpos:=-1;
setPosition(mPos);
end else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Next;
Begin
if FActive then
Begin
if FState=dsIdle then
setPosition(TInteger.EnsureRange(FDsIndex+1,-1,FCache.Length)) else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.Back;
Begin
if FActive then
Begin
if FState=dsIdle then
setPosition(TInteger.EnsureRange(FDsIndex+1,-1,FCache.Length)) else
raise EW3Dataset.Create(CNT_DATASET_INVALID_STATE);
end else
raise EW3Dataset.Create(CNT_DATASET_NOT_ACTIVE);
end;
Procedure TW3CustomDataset.DoBeforeDatasetCreated;
Begin
end;
Procedure TW3CustomDataset.DoAfterDatasetCreated;
Begin
if assigned(FOnCreated) then
Begin
if not FDestroying then
FOnCreated(self);
end;
end;
Procedure TW3CustomDataset.DoBeforeDatasetClosed;
Begin
end;
Procedure TW3CustomDataset.DoAfterDatasetClosed;
Begin
if assigned(FOnClosed) then
Begin
if not FDestroying then
FOnClosed(self);
end;
end;
function TW3CustomDataset.getRecCount:Integer;
Begin
result:=FCache.Length;
end;
function TW3CustomDataset.getRecNo:Integer;
Begin
if FActive then
result:=FDsIndex else
result:=-1;
end;
function TW3CustomDataset.getEOF:Boolean;
Begin
if FActive then
result:=FDsIndex>=FCache.Length else
result:=True;
end;
function TW3CustomDataset.getBOF:Boolean;
Begin
if FActive then
result:=FDsIndex<=0 else
result:=True;
end;
//#############################################################################
// TW3DatasetFields
//#############################################################################
Destructor TW3DatasetFields.Destroy;
Begin
Clear;
inherited;
end;
Procedure TW3DatasetFields.setReadOnly(const aValue:Boolean);
var
x: Integer;
begin
if FFields.Length>0 then
Begin
for x:=FFields.Low to FFields.High do
FFields[x].setReadOnly(aValue);
end;
end;
Function TW3DatasetFields.ExportDefs:String;
Begin
end;
Procedure TW3DatasetFields.ImportDefs(const aDefs:String);
Begin
end;
Procedure TW3DatasetFields.ResetValues;
var
mItem: TW3CustomDatasetField;
Begin
if FFields.Length>0 then
Begin
for mItem in FFields do
mItem.setValue(null);
end;
end;
Procedure TW3DatasetFields.Clear;
var
x: Integer;
Begin
if FFields.Count>0 then
Begin
try
for x:=FFields.Low to FFields.High do
FFields[x].free;
finally
FFields.Clear;
end;
end;
end;
Procedure TW3DatasetFields.DeleteByName(aName:String);
var
mIndex: Integer;
Begin
mIndex:=IndexOf(aName);
if mIndex>=0 then
Begin
FFields[mIndex].free;
FFields.Delete(mIndex,1);
end;
end;
Procedure TW3DatasetFields.Delete(const aIndex:Integer);
Begin
if (aIndex>=0) and (aIndex<FFields.Count) then
Begin
FFields[aIndex].free;
FFields.Delete(aIndex,1);
end;
end;
function TW3DatasetFields.Add(aName:String;
const aKind:TW3DatasetFieldType):TW3CustomDatasetField;
Begin
result:=NIL;
aName:=lowercase(trim(aName));
if aName.Length>0 then
Begin
if IndexOf(aName)=-1 then
Begin
case aKind of
ftBoolean: result:=TW3BooleanField.Create(self);
ftInteger: result:=TW3IntegerField.Create(self);
ftFloat: result:=TW3FloatField.Create(self);
ftString: result:=TW3StringField.Create(self);
ftDateTime: result:=TW3DateTimeField.Create(self);
else result:=NIL;
end;
if result<>NIL then
Begin
result.Name:=aName;
FFields.add(result);
end;
end;
end;
end;
function TW3DatasetFields.DataExport:TW3DatasetPacket;
var
x: Integer;
mField:TW3CustomDatasetField;
Begin
result:=TVariant.CreateObject;
if FFields.count>0 then
Begin
for mField in FFields do
result[mField.Name]:=mField.getValue;
end;
end;
Procedure TW3DatasetFields.DataImport(const aValue:TW3DatasetPacket);
var
mField:TW3CustomDatasetField;
Begin
if FFields.count>0 then
Begin
for mField in FFields do
mField.setvalue(aValue[mField.Name]);
end;
end;
function TW3DatasetFields.IndexOf(aName:String):Integer;
var
x: Integer;
Begin
result:=-1;
aName:=lowercase(trim(aName));
if aName.Length>0 then
Begin
for x:=FFields.Low to FFIelds.High do
Begin
If FFIelds[x].Name=aName then
Begin
result:=x;
break;
end;
end;
end;
end;
function TW3DatasetFields.FieldByName(aName:String):TW3CustomDatasetField;
var
x: Integer;
Begin
result:=NIL;
aName:=lowercase(trim(aName));
if aName.Length>0 then
Begin
for x:=FFields.Low to FFields.High do
Begin
If FFields[x].Name=aName then
Begin
result:=FFields[x];
break;
end;
end;
end;
end;
//#############################################################################
// TW3DateTimeField
//#############################################################################
function TW3DateTimeField.getValue:TDateTime;
Begin
result:=inherited getValue;
end;
procedure TW3DateTimeField.setValue(const aValue:TDateTime);
Begin
inherited setValue(aValue);
end;
//#############################################################################
// TW3CustomDatasetField
//#############################################################################
Constructor TW3CustomDatasetField.Create(const aParent:TW3DatasetFields);
Begin
inherited Create;
FParent:=aParent;
FKind:=ftUnknown;
FName:='Field' + IntToStr( w3_GetUniqueNumber );
end;
Procedure TW3CustomDatasetField.setAsDateTime(const aValue:TDateTime);
Begin
FValue:=aValue;
end;
function TW3CustomDatasetField.getAsDateTime:TDateTime;
Begin
result:=FValue;
end;
function TW3CustomDatasetField.getValue:Variant;
Begin
result:=FValue;
end;
procedure TW3CustomDatasetField.setValue(const aValue:variant);
Begin
FValue:=aValue;
end;
procedure TW3CustomDatasetField.setName(const aValue:String);
Begin
if not FReadOnly then
FName:=lowercase(trim(aValue)) else
Raise EW3DatasetField.Create(CNT_DATASET_FIELD_READONLY);
end;
procedure TW3CustomDatasetField.setKind(const aKind:TW3DatasetFieldType);
Begin
if not FReadOnly then
FKind:=aKind else
Raise EW3DatasetField.Create(CNT_DATASET_FIELD_READONLY);
end;
Procedure TW3CustomDatasetField.setReadOnly(const aValue:Boolean);
Begin
FReadOnly:=aValue;
end;
end.
Smart Pascal dataset
As I have mentioned earlier in my posts, Smart Pascal have no default database framework. Smart Mobile Studio (which is the #1 compiler for Smart Pascal) have wrappers for all the various browser database engines, so using them is greatly simplified for Smart programmers — but there are no such things as datasets, field objects and any of the standard stuff we are used to under Delphi or Freepascal.
Well, today I had enough and started writing the basics!
The cool part is that dealing with data is, believe it or not, much easier in Smart Pascal than under native Delphi. For instance, a row of data (a data packet) is stored in JSON format, and JavaScript’s live prototype nature makes it extremely elegant to read, write and update a large collection of packets. Being able to read, write and update data from your server or the cloud is, to my surprise.. easy as apple pie!
Screendump of my vmware for smart pascal
For instance, what is a record? Answer: It is a collection of persistent, named field objects. Under JavaScript that can be easily represented as a JSON object – or “array of named variants” in Object Pascal terms. So you get the naming of data free of charge, because that’s how JavaScript works. And you also get the serialization of data free of charge, because that’s how JSON works. So roughly 25% of the work required by “native” languages in order to represent a dataset – is already done. Pretty cool huh? 🙂
And yes, this code will work under any Smart Pascal compliant system. DWScript, Smart Mobile Studio and Quartex Pascal. But it will ship first and foremost with Smart Mobile Studio.
And now for something completely different
Bored? Check out the TV series “Silicon Valley” from HBO, I laughed so hard I nearly broke a rib. The series if a complete rip-off from the british “IT crowd” (even the music), but it reminded me so much of Borland vs. Microsoft that I nearly fell out of my couch 😀
Phillipe Kahn on drugs 🙂
Learning Smart Pascal, a primer
One of the questions I get the most when it comes to Smart Pascal and Smart Mobile Studio, is “how do I learn the language?”. The short answer to this question is, if you know Delphi or Freepascal, that you already know it.
Linguistically Smart Pascal is more or less identical to ordinary Object Pascal (Delphi and FreePascal). So as a Delphi programmer you can jump straight into it and start coding – as long as you remember the following:
- JavaScript has no pointers
- You don’t need to postfix your event declarations with “of object”
- Interfaces are supported by TObject
- Threads are written in separate units (web workers)
- Our run-time library is VJL, Visual JavaScript Library
- Sets are not supported, but easily emulated
- Generics is not supported
That really is everything you need to know, taking for granted naturally -that you already know Delphi or Freepascal and are not afraid to write code. I must admit that I did not expect people to be so dependent on the visual designer as they clearly are – but linguistically Smart Pascal is just “Delphi with a twist”. I don’t mean anything negative about that, I was just surprised that so many programmers are like fish out of water when you remove the visual aids. I rarely use the visual designer, except for form layout. Everything else is written in code, class by class, hierarchy by hierarchy.
Once you get used to compiling to JavaScript rather than machine code, you can begin to use the “smart” part of our pascal dialect, namely lambdas, array operations, partial classes, anonymous classes, class variables and much, much more (please see wikipedia article for detailed descriptions of these advances).
The single most powerful difference is probably array operations. Under Delphi you are used to TList, TObjectList and lately, generics (not to mention stacks and queues). Under Smart Pascal arrays are more evolved and replaces these concepts. All arrays, regardless of type, support a wide range of operations. Once you understand how flexible and fast this is – it will change how you write your code profoundly. You might even end up missing these features in Delphi and implement a helper for it (like I have done).
Procedure TForm1.playValues;
var
mItems: Array of Variant;
begin
mItems.add(1200);
mItems.add('this is a string');
mItems.add(12.5);
mItems.push(19.22);
writeln(mItems.pop);
end;
Check out Array Operations on wikipedia for a list of methods supported by all arrays.
Where to begin
Just like under C# you are expected to write code
The reason we did not supply documentation is twofold: when I started the project I designed it to be a Delphi only tool, meaning that you were supposed to simply write ordinary Delphi (hence the link to Delphi Basics in the application). SMS was initially a utility by Delphi programmers for Delphi programmers. Sadly, Embarcadero has made it perfectly clear that they regard us as a threat rather than friends so we had no choice but to abandon VCL emulation and focus on our own, proprietary run-time library.
This attitude still baffles me because it represents a great loss of income and opportunity for Delphi programmers worldwide. Object Pascal as a language is the bread and butter of the Delphi community, and the more people use our language – the greater the interest and investment in Delphi there will be.
But you can probably imagine what our compiler could do if deployed with Delphi. The live HTML5 reporting capabilities alone would revolutionize how we present numbers and interact with online services – and being able to compile to HTML5 would really set Delphi apart from other development platforms. Just imagine Intraweb powered by our compiler technology? Being able to use the same language both natively and in the browser – compiled into lightning fast JavaScript on the spot. That would be a very powerful technology indeed. But sadly this is not something Embarcadero wanted. I have given up on Embarcadero long ago and wont waste any more time regarding this topic.
The second reason is, obviously, JavaScript itself. The reality of the browser is so different and alien compared to the Microsoft Windows API, that a full VCL emulation layer would be fatal to execution time. So while it would be nice to be 100% Delphi compatible both linguistically and architecturally, performance wise it would be suicide. And since Embarcadero made it so clear that our hard work and service to the Delphi community is unwanted (due to the fact that it makes HTML5 builder look like a raving imbecile) it made more sense writing our own from scratch. Smart Mobile Studio is what Delphi for PHP should have been.
A brand new run-time library for a brand new platform, boldly taking Object Pascal where no compiler has gone before.
I am probably the first human being to compile an Object Pascal program and executing it on my Smart TV. Never before has Object Pascal run on a Phillips TV with an embedded browser — and never before have Object Pascal been used to control micro-processors. It was not Embarcadero that delivered this — it was us.
Real code, real work
Get a good book on JavaScript
If you go out and buy Mono C# for mobile development you are expected, just like under Smart Pascal, to study the RTL source-code and familiarize yourself with the units. We have reflected some of the VCL architecture (which really is universal, since that’s how most run-time libraries work), such as TW3CustomControl and TW3Component which are as identical to their Delphi equivalents as JavaScript allows.
You are also expected to tailor custom-controls yourself and adapt the standard controls and classes to your solution. This is how real software is made in all other languages, including Objective C, C# and C++. And while Delphi still retains it’s Visual Basic like, RAD, event driven development interface –Object Pascal is just as capable as C# and C++ for serious development. But the visual design tools quickly go out the window when you want to write rock-solid applications, be they for the mobile platform or not.
So in short: If you know Delphi and are not afraid of writing your own classes, which I really regard as a primer for calling yourself a programmer, then Smart Pascal will be mastered in a couple of days. You can also cut the learning curve even more by getting a book on Smart Pascal.
If you are new to Object Pascal then a quick visit to Delphi Basics will help you learn our language quickly and effectively.
And just like Delphi – we provide a “Demos” folder when you install Smart. This really is the #1 place to find example code. Everything from touch management, scrolling, hardware GPU powered sprites and more is covered here. A wast tome of knowledge ready to be played with and learned from.
If I was to learn Smart Pascal today, I would get the following:
It is not “vital” that you learn JavaScript, but learning about the browser objects, JavaScript libraries and elements is important. But it’s not complex and any middle-level programmer will master the browser quickly. Once you have played around with JavaScript a couple of days, reading about what JavaScript can do and how to do it — then pick up the Smart Book and enjoy.
JavaScript has no classes, no custom types — but Smart Pascal does. It will save you so much time and solve so many common JavaScript problems straight out of the box.
Knowing that you can use Smart Pascal to control hardware, like the new JS based controllers which is making their entry into the embedded marked, hard-core HTML5 mobile applications, games, multimedia and serious business applications — it’s more than worth the couple of days it takes learning the ropes.
Enjoy!
Jon L. Aasenden 
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