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所以，最近我们（我和我的同事）一直在谈论迁移到 FireDac，我们目前正在使用 IBO 和 DBX，但主要是 IBO。然后我们决定把一切从 IBO 带到 FireDac，但是输入每个表单，更改每个 IBOQuery，添加所有字段，设置所有显示格式等等，等等，等等等等，都需要太多时间，所以我们决定做一个组件做到这一点，似乎是一件容易的事，但我刚刚开始，我已经陷入了一些看似简单但我以前从未遇到过的事情。首先我们看一下组件代码：

    unit UMyComponent;

    interface

    uses
      Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
      Vcl.Controls, Vcl.Forms, Vcl.Dialogs, IB_Components, IB_Access,
      IBODataset, Vcl.StdCtrls, Vcl.Buttons, Vcl.Grids, Vcl.DBGrids, Data.DB,
      uADStanIntf, uADStanOption, uADStanParam, uADStanError,
      uADDatSManager, uADPhysIntf, uADDAptIntf, uADStanAsync, uADDAptManager,
      uADCompDataSet, uADCompClient;

    type
      TMyComponent = class(TComponent)
      private
        FADConnection: TADConnection;
        FConverter: String;

        procedure Iniciar;

        procedure SetADConnection(const Value: TADConnection);
        procedure SetConverter(const Value: String);
      published
        property Converter: String read FConverter write SetConverter;
        property ADConnection: TADConnection read FADConnection write SetADConnection;
      end;

    procedure Register;

    implementation

    procedure Register;
    begin
      RegisterComponents('MyComponents', [TMyComponent]);
    end;

    { TMyComponent }

    procedure TMyComponent.Iniciar;
    var
      Form: TForm;
      IBOQuery: TIBOQuery;
      i: Integer;

      procedure _ConverterIBOQuery;
      var
        ADQuery: TADQuery;
        qName: String;
      begin
        qName := IBOQuery.Name;

        if qName.Contains('OLD_') then
          Exit;

        IBOQuery.Name := 'OLD_'+ qName;

        if (FindComponent(qName) = nil) then
        begin
          ADQuery            := TADQuery.Create(Form);
          ADQuery.Name       := qName;
          ADQuery.Connection := FADConnection;
          ADQuery.SQL        := IBOQuery.SQL;

          {
           I need to add the fields here, but I need them having a reference,
           like the ones you Right Click > Fields Editor > Add All Fields (CTRL + F)
           because in the final form of this component, it won't rename the old query
           with an 'OLD_' prefix, it will destroy it, and the fields will be gone too,
           so I need to add them (having the reference) in order to not rewrite any of my code
          }
        end;
      end;
    begin
      if Owner is TForm then
        Form := TForm(Owner);

      if Assigned(Form) then
      begin
        for i := 0 to (Form.ComponentCount -1) do
          {
           I know it will stop in the first query it come across,
           but I'm trying to full convert only one to know if it's actually possible
          }
          if (Form.Components[i] is TIBOQuery) then
          begin
            IBOQuery := TIBOQuery(Form.Components[i]);
            Break;
          end;

        if Assigned(IBOQuery) then
          _ConverterIBOQuery;
      end;
    end;

    procedure TMyComponent.SetConverter(const Value: String);
    begin
      FConverter := UpperCase(Value[1]);

      if (FConverter = 'S') then
        Iniciar;

      FConverter := '';
    end;

    procedure TMyComponent.SetADConnection(const Value: TADConnection);
    begin
      FADConnection := Value;
    end;

    end.

我已经尝试了一些在互联网上找到的方法，例如：

  • 创建 TField 的变量
  • 使用 FieldDefs/FieldDefList，更新它们并创建字段
  • 使用“假”类“破解”ADQuery 以使用 CreateFields 过程

他们都没有达到我的预期，所以我在质疑

我可以通过代码创建字段引用吗？而且，如果可能的话，怎么做？

我的意思是，例如，您有 IBOQuery1，而 SQL 是

SELECT NAME
FROM COUNTRY

之后，您转到 Fields Editor > Add All Fields (CTRL + F)，然后您有引用 IBOQuery1NAME，它是一个 TStringField，您可以只调用 IBOQuery1NAME.AsString 而不是 IBOQuery1.FieldByName('NAME')。字符串

TL;博士

尝试创建将 IBOQuery 迁移到 ADQuery 的组件，但我无法创建引用

4

1 回答 1

2

经过多次尝试和研究，我发现了一个与我的问题相似的老问题，很高兴有一个答案正是我想要的

如何以编程方式将字段添加到 Delphi 中的 TAdoTable

答案由用户提供：Мסž

procedure AddAllFields(DataSet: TDataset);
var
   FieldsList: TStringList;
   FieldName: WideString;
   Field: TField;
   WasActive: boolean;
   FieldDef: TFieldDef;
   i: Integer;
begin
   WasActive := DataSet.Active;
   if WasActive then
      DataSet.Active := False;
   try
      FieldsList := TStringList.Create;
      try
         DataSet.FieldDefs.Update;

         // make a list of all the field names that aren't already on the DataSet
         for i := 0 to DataSet.FieldDefList.Count - 1 do
            with DataSet.FieldDefList[i] do
               if (FieldClass <> nil) and not(faHiddenCol in Attributes) then
               begin
                  FieldName := DataSet.FieldDefList.Strings[i];
                  Field := DataSet.FindField(FieldName);
                  if (Field = nil) or (Field.Owner <> DataSet.Owner) then
                     FieldsList.Add(FieldName);
               end;

         // add those fields to the dataset
         for i := 0 to FieldsList.Count - 1 do
         begin
            FieldDef := DataSet.FieldDefList.FieldByName(FieldName);
            Field := FieldDef.CreateField(DataSet.Owner, nil, FieldName, False);
            try
               Field.name := FieldName + IntToStr(random(MaxInt)); // make the name unique
            except
               Field.Free;
               raise ;
            end;
         end;
      finally
         FieldsList.Free;
      end;
   finally
      if WasActive then
         DataSet.Active := true;
   end;
end;
于 2015-11-20T12:53:41.310 回答