Question

我使用Devexpress的TcxExtLookupComboBox并尝试实现自定义数据源。我已经像这样设置了customdatasource：

procedure TMainForm.FormCreate(Sender: TObject);
begin
  fDataSource := TMyDataSource.Create;
  cbotestSearch.Properties.View.DataController.CustomDataSource := fDataSource;
end;

TMyDataSource在这里定义：

unit Datasource;

interface

uses
  Classes,
  IBQuery,
  SysUtils,
  cxCustomData;

type
  TSearchItem = class
    private
      BoldID: String;
      Display: String
  end;

  TMyDataSource = class(TcxCustomDataSource)
  private
    fSearchList: TList;
  protected
    function GetRecordCount: Integer; override;
    function GetValue(ARecordHandle: TcxDataRecordHandle; AItemHandle: TcxDataItemHandle): Variant; override;
  public
    constructor Create;
    destructor Destroy; override;
    procedure GetData;
  end;

implementation

constructor TMyDataSource.Create;
begin
  inherited Create;
  fSearchList := TList.Create;
end;

destructor TMyDataSource.Destroy;
begin
  FreeAndNil(fSearchList);
  inherited;
end;

procedure TMyDataSource.GetData;
var
  vItem: TSearchItem;
begin
  fSearchList.Clear;

  vItem := TSearchItem.Create;
  vItem.BoldID  := '1000';
  vItem.Display := 'test';
  fSearchList.Add(vItem);

  vItem := TSearchItem.Create;
  vItem.BoldID  := '1100';
  vItem.Display := 'test2';
  fSearchList.Add(vItem);

  DataChanged;    // Don't do anything as provider is nil
end;

function TMyDataSource.GetRecordCount: Integer;
begin
  // Is never entered
  Result := fSearchList.Count;
end;

function TMyDataSource.GetValue(ARecordHandle: TcxDataRecordHandle;
  AItemHandle: TcxDataItemHandle): Variant;
begin
  // Is never entered
  Result := 'Test';
end;

end.

问题是从未调用过TMyDataSource.GetValue。任何提示如何解决？

更新1：我在这里有另一个提示。如果我在DataChanged方法中单步执行应该导致调用GetValue的步骤如下所示：

procedure TcxCustomDataSource.DataChanged;
begin
  if Provider = nil then Exit;

  // Code using Provider
end;

在这种情况下，

和提供商是零。但是，如您所见，我已在Forms oncreate中分配了数据源。

Answer 1

cxExtLookupComboBox只能用于DB~view。此类视图不能接受TcxCustomDataSource对象的实例作为DataSource。所以，你的代码将不起作用:-(。有一个建议在未来实现这个功能，并在以下网站注册：

http://www.devexpress.com/Support/Center/ViewIssue.aspx?issueid=AS10025

如何在TcxExtLookupComboBox中使用TcxCustomDataSource？

1 个答案: