windows – 我需要避免尝试更新连接到TSQLQuery的Delphi TClient

根据您对问题的评论,我建议您在类中创建一个新方法来打开内部ClientDataSet,所有魔法都将在此方法中进行.

首先,一个简单的机制是包含一个新的TStringList属性,该属性列出了您要忽略的所有字段,您将按名称进行匹配.随意采用这个或创建一个新的更好的机制,重要的是你能够识别出你想要配置哪个字段.

type
  TMyClass = class
    // all your current class here
  private
    FUpdateIgnoredFields: TStringList;
  public
    property UpdateIgnoredFields: TStringList read FUpdateIgnoredFields write SetUpdateIgnoredFields;
    //don't forget to create this in your constructor,free it in the destructor
    //and Assign any new value in the SetUpdateIgnoreFields method,as usual.
    procedure OpenInnerCDS; //the magic goes here
  end;

procedure TMyClass.OpenInnerCDS;
var
  FieldName: string;
  AFieldToIgnore: TField;
begin
  //opens the inner cds,but before that,configures the update-ignored  
  //fields in the underlying dataset
  //Let's call it InnerBaseDataSet;
  FInnerBaseDataSet.Open; //this opens the DataSet and creates all the fields for it.
  try
    for FieldName in FUpdateIgnoredFields do
    begin
      AFieldToIgnore := FInnerBaseDataSet.FindField(FieldName);
      if Assigned(AFieldToIgnore) then
        AFieldToIgnore.ProviderFlags := AFieldToIgnore.ProviderFlags - [pfInUpdate,pfInWhere];
    end;
    //now,let's open the ClientDataSet;
    FInnerClientDataSet.Open;
  finally
    //I suggest no matter what happens,always close the inner data set
    //but it depends on how the CDS->Provider->DataSet interaction is configured
    FInnerBaseDataSet.Close;
  end;
end;

//the way you use this is to replace the current ClientDataSetOpen with something like:

var
  MyInsance: TMyClass;
begin
  MyInstance := TMyInstance.Create();  //params
  try
    //configuration code here
    //MyInstance.InnerCDS.Open;  <-- not directly now
    MyInstance.UpdateIgnoreFields.Add('CALCULATED_SALARY');
    MyInstance.OpenInnerCDS;
    //use the CDS here.
    MyInstance.InnerCDS.ApplyUpdates(-1); //safely apply updates now.
  finally
    MyInstance.Free;
  end;
end;

把它作为一个想法.

我在这里编写了所有代码,也许语法错了,但它显示了整个想法.