TBooleanField Class

TBooleanField represents a field containing Boolean values.

Pascal

TBooleanField = class(TField);

C++

class TBooleanField : public TField;

File

Description

TBooleanField encapsulates the fundamental behavior common to Boolean data. Boolean fields can hold values of true or false.

In addition to the properties, methods, and events common to all fields that are introduced by the TField class, TBooleanField introduces new properties to convert between boolean values and other data types, and to provide display strings that represent various interpretations of the data.

If you use the Fields editor at design time to create a persistent field component for the boolean field, you can access it by name at runtime. When using dynamic field components, you can access the TBooleanField instance using the dataset's Fields property or FieldByName method.

Delphi Examples:

Copy Code

{
This example requires a button, a test edit, and a populated
ClientDataSet.  Pipe the ClientDataSet through a DataSource
to a DGGrid or DBNavigator to control the current field.
Cast the data correctly according to the field type when
assigning to the test edit.
}

{$IFNDEF UNICODE}
uses SwSystem;
{$ENDIF}

procedure TForm1.Button1Click(Sender: TObject);
var MyBuffer: Pointer;
begin
{ Retrieve the "raw" data from Field1 }
with CDS.Fields[0] do
  begin
    if not IsBlob then { this does not work for BLOB fields }
    begin
      { Allocate space }
      MyBuffer:= GetMemory(DataSize);
      try
        if not GetData(MyBuffer) then
          MessageDlg(DisplayName + ' is NULL', mtInformation, [mbOK], 0)
        else
          { Do something with the data };
          Edit1.Text:= string(PAnsiChar(MyBuffer)); // for a stringfield
      finally
        { Free the space }
        FreeMem(MyBuffer, DataSize);
      end;
    end;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
{$IFDEF UNICODE}
  CDS.LoadFromFile(GetCurrentDir + '\CDS.XML');
{$ELSE}
  CDS.LoadFromFile(gsAppPath + 'CDS.XML');
{$ENDIF}
end;