避免调用重复验证

Question

我有点卡住了。我的目标是始终检查和验证我的货币字段，当它的值发生变化时，不管是从内联代码还是从用户界面。是否有任何验证模式或样本？我想避免调用我的验证程序两次。

如有任何帮助或建议，我们将不胜感激。

这是我的例子：

type
TMyForm = class(TForm)   
  ceMyCurrencyEdit: TcxCurrencyEdit;
  procedure FormShow(Sender: TObject);
private
{ Private declarations }
  procedure SetupMyForm;
public
{ Public declarations }
  procedure ValidateMyCurrencyValue;
  function IsValidCurrency: Boolean;
end; 

procedure TMyForm.ValidateMyCurrencyField;
begin
  if not IsValidCurrency then
  begin
    WarningDlg(
       Format(
           'InValid value in field: [%s..%s]',
           [Formatfloat(ceMyCurrencyEditDisplayFormat, ceMyCurrencyEdit.MinValue),
           Formatfloat(ceMyCurrencyEdit.DisplayFormat, ceMyCurrencyEdit.MaxValue)]
        )
    );
    ceMyCurrencyEdit.Value := ceMyCurrencyEdit.MinValue; 
  end;   
end;

function TMyForm.IsValidCurrency: Boolean;
begin
  Result := (ceMyCurrencyEdit.Value >= ceMyCurrencyEdit.MinValue) and (ceMyCurrencyEdit.Value <= ceMyCurrencyEdit.MaxValue);  
end;

procedure TMyForm.SetupMyForm;
begin
  //MaxValue is 100
  ceMyCurrencyEdit.Value := 102;
  //At this point I need to call ValidateMyCurrencyField to get warning msg and refuse its value
  ValidateMyCurrencyField;
end;

procedure TMyForm.FormShow(Sender: TObject);
begin
  SetupMyForm;
end;

procedure TMyForm.ceMyCurrencyEditPropertiesEditValueChanged(Sender: TObject);
begin
  ValidateMyCurrencyField;
end;

我想要的是...

感谢您的回答！

Answer 1

我不确定为什么你似乎有点不屑一顾 os @Nil 的建议，但在下面是一个示例项目，它显示了使用 cxCurrencyEdit 的验证工具并使用 interposer TcxCurrencyEdit class 记录验证结果在其 ValidationState 属性.

中处理

显然你可以使用 ValidationState 属性来避免重复你的验证过程，或者如果国家说它是有效的，就真的这样做。但是，就性能而言，我非常怀疑您是否会自救任何东西。

很明显，interposer class的重点是记录验证状态控件，这样您就可以避免对其进行第二次验证。是否与 cxCurrencyEdit1PropertiesValidate 事件结合使用完全取决于您。

我让你将它与你现有的代码结合起来。

顺便说一句，TEdit 控件就在那里允许焦点从 cxCurrencyEdit 转移到触发它的 cxCurrencyEdit1PropertiesValidate 事件。

更新您在评论中询问了验证代码中设置的值。和一个 interposer class，很容易为值属性添加一个 Getter 和 Setter 并在 Setter 中进行验证 - 请参阅下面的 `SetValue，

  type
    TCurrencyValidation = (cvNotDone, cvOK, cvInvalid);

    TcxCurrencyEdit = class(cxCurrencyEdit.TcxCurrencyEdit)
    private
      FValidationState : TCurrencyValidation;
      function GetValue: Double;
      procedure SetValue(const AValue: Double);
    protected
      property ValidationState : TCurrencyValidation read FValidationState write FValidationState;
    published
      property Value : Double read GetValue write SetValue;
    end;

    TForm1 = class(TForm)
      cxCurrencyEdit1: TcxCurrencyEdit;
      Edit1: TEdit;
      procedure FormCreate(Sender: TObject);
      procedure cxCurrencyEdit1PropertiesChange(Sender: TObject);
      procedure cxCurrencyEdit1PropertiesValidate(Sender: TObject;
        var DisplayValue: Variant; var ErrorText: TCaption;
        var Error: Boolean);
    end;

  procedure TForm1.FormCreate(Sender: TObject);
  begin
    cxCurrencyEdit1.Properties.MinValue := 5;
    cxCurrencyEdit1.Properties.MaxValue := 10;
    cxCurrencyEdit1.Value := 8;
  end;

  procedure TForm1.cxCurrencyEdit1PropertiesChange(Sender: TObject);
  begin
    TcxCurrencyEdit(Sender).ValidationState := cvNotDone;
  end;

  procedure TForm1.cxCurrencyEdit1PropertiesValidate(Sender: TObject;
    var DisplayValue: Variant; var ErrorText: TCaption; var Error: Boolean);
  var
    Min,
    Max : Double;
  begin
    Min := TcxCurrencyEdit(Sender).Properties.MinValue;
    Max := TcxCurrencyEdit(Sender).Properties.MaxValue;
    if (DisplayValue >= Min) and (DisplayValue <= Max) then
      TcxCurrencyEdit(Sender).ValidationState := cvOK
    else
      TcxCurrencyEdit(Sender).ValidationState := cvInvalid;
    Error := not (TcxCurrencyEdit(Sender).ValidationState = cvOK);
    if Error then
      ErrorText := 'InvalidValue';
  end;

  function TcxCurrencyEdit.GetValue: Double;
  begin
    Result := inherited Value;
  end;

  procedure TcxCurrencyEdit.SetValue(const AValue: Double);
  begin
    //  insert code to validate AValue here
    inherited Value := AValue;
  end;

避免调用重复验证

Avoid calling duplication for validation

delphi

delphi-10.1-berlin

delphi-10.2-tokyo