Query component

Finally, let’s examine the last component, TfrxIBXQuery. It inherits from TfrxCustomQuery basic class, in which necessary properties are already defined. We only need to define Database property and override SetMaster method. Other methods realization is similar to TfrxIBXTable component.

  TfrxIBXQuery = class(TfrxCustomQuery)
  private
    FDatabase: TfrxIBXDatabase;
    FQuery: TIBQuery;
    procedure SetDatabase(const Value: TfrxIBXDatabase);
  protected
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
    procedure SetMaster(const Value: TDataSource); override;
    procedure SetSQL(Value: TStrings); override;
    function GetSQL: TStrings; override;
  public
    constructor Create(AOwner: TComponent); override;
    constructor DesignCreate(AOwner: TComponent; Flags: Word); override;
    class function GetDescription: String; override;
    procedure BeforeStartReport; override;
    procedure UpdateParams; override;
    property Query: TIBQuery read FQuery;
  published
    property Database: TfrxIBXDatabase read FDatabase write SetDatabase;
  end;

constructor TfrxIBXQuery.Create(AOwner: TComponent);
begin
  { create component – query }
  FQuery := TIBQuery.Create(nil);
  { assign link to it to DataSet property from basic class – do not forget this line! }
  Dataset := FQuery;
  { assign link to connection to DB by default }
  SetDatabase(nil);
  { after that basic constructor may be called in }
  inherited;
end;

constructor TfrxIBXQuery.DesignCreate(AOwner: TComponent; Flags: Word);
var
  i: Integer;
  l: TList;
begin
  inherited;
  l := Report.AllObjects;
  for i := 0 to l.Count - 1 do
    if TObject(l[i]) is TfrxIBXDatabase then
    begin
      SetDatabase(TfrxIBXDatabase(l[i]));
      break;
    end;
end;

class function TfrxIBXQuery.GetDescription: String;
begin
  Result := 'IBX Query';
end;

procedure TfrxIBXQuery.Notification(AComponent: TComponent; Operation: TOperation);
begin
  inherited;
  if (Operation = opRemove) and (AComponent = FDatabase) then
    SetDatabase(nil);
end;

procedure TfrxIBXQuery.SetDatabase(const Value: TfrxIBXDatabase);
begin
  FDatabase := Value;
  if Value <> nil then
    FQuery.Database := Value.Database
  else if IBXComponents <> nil then
    FQuery.Database := IBXComponents.DefaultDatabase
  else
    FQuery.Database := nil;
  DBConnected := FQuery.Database <> nil;
end;

procedure TfrxIBXQuery.SetMaster(const Value: TDataSource);
begin
  FQuery.DataSource := Value;
end;

function TfrxIBXQuery.GetSQL: TStrings;
begin
  Result := FQuery.SQL;
end;

procedure TfrxIBXQuery.SetSQL(Value: TStrings);
begin
  FQuery.SQL := Value;
end;

procedure TfrxIBXQuery.UpdateParams;
begin
  { in this method it is sufficient to assign values from Params into FQuery.Params }
  { this is performed via standard procedure }
  frxParamsToTParams(Self, FQuery.Params);
end;

procedure TfrxIBXQuery.BeforeStartReport;
begin
  SetDatabase(FDatabase);
end;