cxdbfilter.pas

来自「胜天进销存源码,国产优秀的进销存」· PAS 代码 · 共 127 行

{********************************************************************}
{                                                                    }
{       Developer Express Visual Component Library                   }
{       ExpressDataController                                        }
{                                                                    }
{       Copyright (c) 1998-2008 Developer Express Inc.               }
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{   RESTRICTIONS                                                     }
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{********************************************************************}

unit cxDBFilter;

{$I cxVer.inc}

interface

uses
  DB, cxFilter, cxDB;

type
  { TcxFilterSQLNullOperator }

  TcxFilterSQLNullOperator = class(TcxFilterNullOperator)
  public
    function FilterText: string; override;
  end;

  { TcxFilterSQLNotNullOperator }

  TcxFilterSQLNotNullOperator = class(TcxFilterNotNullOperator)
  public
    function FilterText: string; override;
  end;

  { TcxDBFilterOperatorAdapter }

  TcxDBFilterOperatorAdapter = class(TcxDBAdapterItem)
  public
    procedure PrepareOperatorClass(ASender: TObject; ADataSet: TDataSet;
      var AOperatorClass: TcxFilterOperatorClass); virtual;
  end;

function cxGetFilterOperatorAdapter(ADataSet: TDataSet): TcxDBFilterOperatorAdapter;

var
  cxFilterOperatorAdapters: TcxDBAdapterList;
  
implementation

uses
  SysUtils;

function cxGetFilterOperatorAdapter(ADataSet: TDataSet): TcxDBFilterOperatorAdapter;
var
  AIndex: Integer;
begin
  if Assigned(ADataSet) and cxFilterOperatorAdapters.FindAdapter(TDataSetClass(ADataSet.ClassType), AIndex) then
    Result := cxFilterOperatorAdapters[AIndex] as TcxDBFilterOperatorAdapter
  else
    Result := nil;
end;

{ TcxFilterSQLNullOperator }

function TcxFilterSQLNullOperator.FilterText: string;
begin
  Result := 'IS';
end;

{ TcxFilterSQLNotNullOperator }

function TcxFilterSQLNotNullOperator.FilterText: string;
begin
  Result := 'IS NOT';
end;

{ TcxDBFilterOperatorAdapter }

procedure TcxDBFilterOperatorAdapter.PrepareOperatorClass(ASender: TObject;
  ADataSet: TDataSet; var AOperatorClass: TcxFilterOperatorClass);
begin
  if AOperatorClass.InheritsFrom(TcxFilterNullOperator) or
    AOperatorClass.InheritsFrom(TcxFilterNotNullOperator) then
  begin
    if Pos(AnsiUpperCase('Query'), AnsiUpperCase(ADataSet.ClassName)) <> 0 then
      if AOperatorClass.InheritsFrom(TcxFilterNotNullOperator) then
        AOperatorClass := TcxFilterSQLNotNullOperator
      else
        AOperatorClass := TcxFilterSQLNullOperator;
  end;
end;

initialization
  cxFilterOperatorAdapters := TcxDBAdapterList.Create;
  cxFilterOperatorAdapters.RegisterAdapter(TDataSet, TcxDBFilterOperatorAdapter);

finalization
  cxFilterOperatorAdapters.Free;
  cxFilterOperatorAdapters := nil;

end.