RAD Studio VCL Reference
|
Creates a new field parameter object and inserts it into the Items list.
function CreateParam(FldType: TFieldType; const ParamName: string; ParamType: TParamType): TParam;
__fastcall TParam CreateParam(TFieldType FldType, const AnsiString ParamName, TParamType ParamType);
Call CreateParam to instantiate a new TParam object and add it to the Items managed by this TParams object. Specify the field type of the new parameter as the value of FldType, specify the name of the parameter as the value of ParamName, and specify the type of parameter as the value of ParamType.
Delphi Examples:
{ This example saves params from a ClientDataSet, alters them and restores them. } procedure TForm1.SaveParamsClick(Sender: TObject); begin { Save the parameters for the TDataSet } SavedParams.Assign(CDS.Params); end; procedure TForm1.AlterParamsClick(Sender: TObject); var I : Integer; ListItem: string; begin CDS.Params.CreateParam(ftString, 'stringParam', ptInput); // you can also edit the params in the CDS dynamically CDS.Params.CreateParam(ftSmallInt, 'smallIntParam', ptInput); CDS.Params.CreateParam(ftInteger, 'intParam', ptInput); CDS.Params.CreateParam(ftWord, 'wordParam', ptInput); CDS.Params.CreateParam(ftBoolean, 'boolParam', ptInput); CDS.Params.CreateParam(ftFloat, 'floatParam', ptInput); CDS.Params.CreateParam(ftCurrency, 'currencyParam', ptInput); CDS.Params.CreateParam(ftBCD, 'bcdParam', ptInput); CDS.Params.CreateParam(ftDate, 'dateParam', ptInput); CDS.Params.CreateParam(ftTime, 'timeParam', ptInput); CDS.Params.CreateParam(ftDateTime, 'dateTimeParam', ptInput); { Call FetchParams to ensure parameters reflect server metadata } CDS.FetchParams; with CDS.Params do begin for I := 0 to Count - 1 do begin ListItem := ListBox1.Items[I]; case Items[I].DataType of ftString: Items[I].AsString := ListItem; ftSmallInt: Items[I].AsSmallInt := StrToIntDef(ListItem, 0); ftInteger: Items[I].AsInteger := StrToIntDef(ListItem, 0); ftWord: Items[I].AsWord := StrToIntDef(ListItem, 0); ftBoolean: begin if ListItem = 'True' then Items[I].AsBoolean := True else Items[I].AsBoolean := False; end; ftFloat: Items[I].AsFloat := StrToFloat(ListItem); ftCurrency: Items[I].AsCurrency := StrToFloat(ListItem); ftBCD: Items[I].AsBCD := StrToCurr(ListItem); ftDate: Items[I].AsDate := StrToDate(ListItem); ftTime: Items[I].AsTime := StrToTime(ListItem); ftDateTime: Items[I].AsDateTime := StrToDateTime(ListItem); end; end; end; end; procedure TForm1.RestoreParamsClick(Sender: TObject); begin { Restore the parameters to TDataSet } CDS.Params.AssignValues(SavedParams); end; procedure TForm1.FormCreate(Sender: TObject); begin { Initialize SavedParams } SavedParams := TParams.Create; ListBox1.Items.Add('Here is a string'); ListBox1.Items.Add('4'); ListBox1.Items.Add('3456789'); ListBox1.Items.Add('34'); ListBox1.Items.Add('0'); ListBox1.Items.Add('12.56'); ListBox1.Items.Add('4.23'); ListBox1.Items.Add('99.5'); ListBox1.Items.Add('4/12/53'); ListBox1.Items.Add('7:45:00'); ListBox1.Items.Add('4/12/53 7:45:00'); end; procedure TForm1.FormDestroy(Sender: TObject); begin SavedParams.Free; end;
{ This example saves params from a ClientDataSet, alters them and restores them. } procedure TForm1.SaveParamsClick(Sender: TObject); begin { Save the parameters for the TDataSet } SavedParams.Assign(CDS.Params); end; procedure TForm1.AlterParamsClick(Sender: TObject); var I : Integer; begin CDS.Params.CreateParam(ftInteger, 'StateParam', ptInput); CDS.Params.CreateParam(ftInteger, 'MyParam', ptInput); for I := 0 to CDS.Params.Count - 1 do if (CDS.Params.Items[I].IsNull) and (CDS.Params.Items[I].DataType = ftInteger) then { Items is the default property, so you can omit its name } CDS.Params[I].AsInteger := -1; end; procedure TForm1.RestoreParamsClick(Sender: TObject); begin { Restore the parameters to TDataSet } CDS.Params.AssignValues(SavedParams); end; procedure TForm1.FormCreate(Sender: TObject); begin { Initialize SavedParams } SavedParams := TParams.Create; end; procedure TForm1.FormDestroy(Sender: TObject); begin SavedParams.Free; end;
Copyright(C) 2008 CodeGear(TM). All Rights Reserved.
|
What do you think about this topic? Send feedback!
|