TFDDataSet descendant, overriding FetchOptions.Mode from design time value

[WalkingAway 1]

I have such a test classes (copy of TFDAdaptedDataSet, TFDCustomMemTable and TFDMemTable):

unit xDataSet;

interface

uses
  System.SysUtils, System.Classes, Data.DB,
  FireDAC.Comp.DataSet,
  Firedac.Stan.Def,
  Firedac.Stan.Param,
  Firedac.Stan.Option,
  Firedac.DatS,
  Firedac.Phys.Intf;

type
  TxBaseDataSet = class(TFDDataSet)
  private
    { Private declarations }
  protected
    { Protected declarations }
  public
    { Public declarations }

    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;

    { TFDDataSet }
    property FetchOptions;
    property FormatOptions;
    property ResourceOptions;
    property SecurityOptions;
    property UpdateOptions;
  published
    { Published declarations }
  end;

  TxCustomDataSet = class(TxBaseDataSet)
  private
    FOptionsIntf: IFDStanOptions;
  protected
    FStoreDefs: Boolean;

    property StoreDefs: Boolean read FStoreDefs write FStoreDefs default False;
    // IFDStanOptions
    function GetOptionsIntf: IFDStanOptions; override;
    procedure GetParentOptions(var AOpts: IFDStanOptions);
 public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;

  TxDataSet = class(TxCustomDataSet)
  published
    property ActiveStoredUsage;
    { TDataSet }
    property Active;
    property AutoCalcFields;
    property BeforeOpen;
    property AfterOpen;
    property BeforeClose;
    property AfterClose;
    property BeforeInsert;
    property AfterInsert;
    property BeforeEdit;
    property AfterEdit;
    property BeforePost;
    property AfterPost;
    property BeforeCancel;
    property AfterCancel;
    property BeforeDelete;
    property AfterDelete;
    property BeforeScroll;
    property AfterScroll;
    property BeforeRefresh;
    property AfterRefresh;
    property OnCalcFields;
    property OnDeleteError;
    property OnEditError;
    property OnNewRecord;
    property OnPostError;
    property FieldOptions;
    property Filtered;
    property FilterOptions;
    property Filter;
    property OnFilterRecord;
    property ObjectView default True;
    property Constraints;
    property DataSetField;
    property FieldDefs stored FStoreDefs;
    { TFDDataSet }
    property CachedUpdates;
    property FilterChanges;
    property IndexDefs stored FStoreDefs;
    property Indexes;
    property IndexesActive;
    property IndexName;
    property IndexFieldNames;
    property Aggregates;
    property AggregatesActive;
    property ConstraintsEnabled;
    property MasterSource;
    property MasterFields;
    property DetailFields;
    property OnUpdateRecord;
    property OnUpdateError;
    property OnReconcileError;
    property BeforeApplyUpdates;
    property AfterApplyUpdates;
    property BeforeGetRecords;
    property AfterGetRecords;
    property AfterGetRecord;
    property BeforeRowRequest;
    property AfterRowRequest;
    property BeforeExecute;
    property AfterExecute;
    property FetchOptions;
    property FormatOptions;
    property ResourceOptions;
    property SecurityOptions;
    property UpdateOptions;

    { TxCustomCustomDataset }
    property StoreDefs;
 public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Samples', [TxDataSet]);
end;

{ TxBaseDataSet }

constructor TxBaseDataSet.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
end;

destructor TxBaseDataSet.Destroy;
begin
  inherited Destroy;
end;

{ TxustomCustomDataset }

constructor TxCustomDataSet.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
end;

destructor TxCustomDataSet.Destroy;
begin
  Close;
  Destroying;
  inherited Destroy;
  if FOptionsIntf <> nil then begin
    FOptionsIntf.ObjectDestroyed(Self);
    FOptionsIntf := nil;
  end;
end;

function TxCustomDataSet.GetOptionsIntf: IFDStanOptions;
begin
  if FOptionsIntf = nil then
    FOptionsIntf := TFDOptionsContainer.Create(Self, TFDFetchOptions,
      TFDBottomUpdateOptions, TFDBottomResourceOptions, GetParentOptions);
  Result := FOptionsIntf;
end;

procedure TxCustomDataSet.GetParentOptions(var AOpts: IFDStanOptions);
begin
  AOpts := nil;
end;

{ TxDataSet }

constructor TxDataSet.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
end;

destructor TxDataSet.Destroy;
begin
  inherited Destroy;
end;

end.

Nothing wrong here. But I can not add quite simple thing - I want to override FetchOptions.Mode (let say, it alway has to be fmAll - no metter what was set in design time).

What I see - value from design time is always som how written in the end. So, when I put 

FetchOptions.Mode = fmAll

to all three available Create methods - constractors,  nothing changes.

How to do it?

 

Also, if I put component to form and ask its mode, it is always what was set in design time.

procedure TForm22.Button1Click(Sender: TObject);
begin
  case xDataSet1.FetchOptions.Mode of
    fmAll: begin
      ShowMessage('fmAll');
    end;
    fmExactRecsMax: begin
      ShowMessage('fmExactRecsMax');
    end;
    fmManual: begin
      ShowMessage('fmManual');
    end;
    fmOnDemand: begin
      ShowMessage('fmOnDemand');
    end;
  end;
end;

Thank you.

Edited February 19 by WalkingAway
mistakes

[PeterBelow 250]

Components dropped at design time load their properties from the dfm file after the constructor has executed. To set a property to a different value you need to override the Loaded method and do the deed there.

[WalkingAway 1]

Thank you. It works