Question

这是我用来从DevExpress网格中的过滤器获取filtertype运算符的codesnippet： OperatorKindToStr用于从过滤器中提取operatorkind作为字符串并将其存储在xml文件中。 StrToOperatorKind用于从xml转换回字符串以在过滤器中设置operatorkind。

const
  CUSTFILTER_FILTERITEM     = 'FilterItem';

function OperatorKindToStr(const aOperatorKind: TcxFilterOperatorKind): string;
begin
  Result := 'foEqual';
  case aOperatorKind of
    foEqual:        Result := 'foEqual';
    foNotEqual:     Result := 'foNotEqual';
    foLess:         Result := 'foLess';
    foLessEqual:    Result := 'foLessEqual';

  // Plus a boring list of other constants
end;

function StrToOperatorKind(const aOpKindStr: string): TcxFilterOperatorKind;
begin
  Result := foEqual;
  if aOpKindStr       = 'foNotEqual' then
    Result := foNotEqual
  else if aOpKindStr  = 'foLess' then
    Result := foLess
  else if aOpKindStr  = 'foLessEqual' then
    Result := foLessEqual
  else if aOpKindStr  = 'foGreater' then
    Result := foGreater
  else if aOpKindStr  = 'foGreaterEqual' then
    Result := foGreaterEqual

  // Plus a boring list of other if-else
end;

procedure UseStrToOperatorKind(const aFilterItem: IXmlDomElement);
begin
  if aFilterItem.nodeName = CUSTFILTER_FILTERITEM then
  begin                              // It is an FilterItem
    vStr := VarToStr(aFilterItem.getAttribute(CUSTFILTER_COLPROP));  // Get the columnname
    vOperatorKind := StrToOperatorKind(aFilterItem.getAttribute(CUSTFILTER_ITEMOPERATOR));
end;

procedure UseOperatorKindToStr(const aFilterItem: TcxCustomFilterCriteriaItem);
var
  vStr: String;
begin
  if Supports(TcxFilterCriteriaItem(aFilterItem).ItemLink, TcxGridColumn, GridCol) then
    vStr := OperatorKindToStr(TcxFilterCriteriaItem(aFilterItem).OperatorKind);
end;

显然我希望StrToOperatorKind和OperatorKindToStr更聪明一些。我在VCL TypeInfo中尝试了GetEnumProp方法，但它不起作用。那么如何从aFilterItem变量中将TcxFilterOperatorKind属性提取为字符串并返回到TcxFilterOperatorKind？

Answer 1

GetEnumProp无法正常工作，因为这是您尝试做的错误功能。不过你很亲密。尝试GetEnumName和GetEnumValue，它们也在TypInfo单元中。

Answer 2

正如梅森指出的那样，使用 GetEnumName 和 GetEnumValue 二重唱。

你的功能应该变得更简单：

function OperatorKindToStr(const aOperatorKind: TcxFilterOperatorKind): string;
begin
  Result := GetEnumName(TypeInfo(TcxFilterOperatorKind), Ord(aOperatorKind));
end;

function StrToOperatorKind(const aOpKindStr: string): TcxFilterOperatorKind;
begin
  Result := TcxFilterOperatorKind(GetEnumValue(TypeInfo(TcxFilterOperatorKind), aOpKindStr));
end;

将DevExpress TcxFilterOperatorKind转换为字符串和从字符串转换？

2 个答案: