LCL, implements NullValueKey for dblookuplistbox and dblookupcombobox, issue #14408

git-svn-id: trunk@28158 -

lcl/dbctrls.pp

@@ -143,6 +143,8 @@ Type
     FListField: TField;  // Result field in lookup dataset
     FLookupCache: boolean;
     FLookupList: TLookupList;
+    FNullValueKey: TShortcut;
+    FOnClearSelection: TNotifyEvent;
     procedure ActiveChange(Sender: TObject);
     procedure EditingChange(Sender: TObject);
     procedure FetchLookupData;
@@ -154,9 +156,11 @@ Type
     procedure SetListFieldName(const Value: string);
     procedure SetListSource(Value: TDataSource);
     procedure SetLookupCache(const Value: boolean);
+    procedure NullKeyHandler(Sender: TObject; var Key: Word; Shift: TShiftState);
   protected
     procedure Notification(AComponent: TComponent;
       Operation: TOperation); override;
+    procedure DoClearSelection;
   public
     constructor Create(AOwner: TComponent); override;
     destructor Destroy; override;
@@ -172,6 +176,8 @@ Type
     property ListField: string read FListFieldName write SetListFieldName;
     property ListFieldIndex: Integer read FListFieldIndex write FListFieldIndex default 0;
     property ListSource: TDataSource read GetListSource write SetListSource;
+    property NullValueKey: TShortcut read FNullValueKey write FNullValueKey;
+    property OnClearSelection: TNotifyEvent read FOnClearSelection write FOnClearSelection;
   end;
 
   { TDBEdit }
@@ -444,12 +450,15 @@ Type
     function GetListFieldIndex: Integer;
     function GetListSource: TDataSource;
     function GetLookupCache: boolean;
+    function GetNullValueKey: TShortCut;
     procedure SetKeyField(const Value: string);
     procedure SetKeyValue(const AValue: Variant);
     procedure SetListField(const Value: string);
     procedure SetListFieldIndex(const Value: Integer);
     procedure SetListSource(const Value: TDataSource);
     procedure SetLookupCache(const Value: boolean);
+    procedure RemoveSelection(Sender: TObject);
+    procedure SetNullValueKey(const AValue: TShortCut);
   protected
     procedure DataChange(Sender: TObject); override;
     procedure InitializeWnd; override;
@@ -473,6 +482,7 @@ Type
     property ListFieldIndex: Integer read GetListFieldIndex write SetListFieldIndex;
     property ListSource: TDataSource read GetListSource write SetListSource;
     property LookupCache: boolean read GetLookupCache  write SetLookupCache;
+    property NullValueKey: TShortCut read GetNullValueKey write SetNullValueKey default 0;
 //    property MultiSelect;
     property OnClick;
     property OnDblClick;
@@ -755,12 +765,15 @@ Type
     function GetListFieldIndex: Integer;
     function GetListSource: TDataSource;
     function GetLookupCache: boolean;
+    function GetNullValueKey: TShortCut;
     procedure SetKeyField(const Value: string);
     procedure SetKeyValue(const AValue: variant);
     procedure SetListField(const Value: string);
     procedure SetListFieldIndex(const Value: Integer);
     procedure SetListSource(const Value: TDataSource);
     procedure SetLookupCache(const Value: boolean);
+    procedure SetNullValueKey(const AValue: TShortCut);
+    procedure RemoveSelection(Sender: TObject);
   protected
     procedure InitializeWnd; override;
     procedure UpdateData(Sender: TObject); override;
@@ -792,6 +805,7 @@ Type
     property ListSource: TDataSource read GetListSource write SetListSource;
     property LookupCache: boolean read GetLookupCache  write SetLookupCache;
 //    property MaxLength default -1;
+    property NullValueKey: TShortCut read GetNullValueKey write SetNullValueKey default 0;
     property OnChange;
     property OnChangeBounds;
     property OnClick;

lcl/include/dblookup.inc

@@ -75,6 +75,7 @@ begin
   FHasLookUpField:= False;
   FListLinkTmpSetActive := False;
   FLookupCache := False;
+  Application.AddOnKeyDownBeforeHandler(@NullKeyHandler, false);
 end;
 
 destructor TDBLookup.Destroy;
@@ -146,6 +147,27 @@ begin
     FLookupList := TLookupList.Create;
 end;
 
+procedure TDBLookup.NullKeyHandler(Sender: TObject; var Key: Word;
+  Shift: TShiftState);
+var
+  i:  Integer;
+begin
+  if (FNullValueKey=KeyToShortCut(Key, Shift)) then
+  begin
+    // null associated field
+    if Assigned(FControlLink) and (FDataFieldNames<>'') and FControlLink.Active then
+    begin
+      FControlLink.DataSet.Edit;
+      for i:=0 to FDataFields.Count-1 do
+        TField(FDataFields[i]).Clear;
+    end else
+    if Assigned(FListLink.DataSet) and FListLink.DataSet.Active and Assigned(FListField) then
+      // associated list is active, clear current selection
+      DoClearSelection;
+  end;
+
+end;
+
 procedure TDBLookup.Notification(AComponent: TComponent; Operation: TOperation);
 begin
   inherited Notification(AComponent, Operation);
@@ -154,6 +176,12 @@ begin
       FListSource:= nil;
 end;
 
+procedure TDBLookup.DoClearSelection;
+begin
+  if Assigned(FOnClearSelection) then
+    OnClearSelection(Self);
+end;
+
 procedure TDBLookup.LinkGetBookMark;
 begin
   FListLinkTmpSetActive := not FListLink.DataSet.Active;

lcl/include/dblookupcombobox.inc

@@ -27,6 +27,7 @@ constructor TDBLookupComboBox.Create(AOwner: TComponent);
 begin
   inherited Create(AOwner);
   FLookup:= TDBLookup.Create(Self);
+  FLookup.OnClearSelection:=@RemoveSelection;
   FDataLink.OnActiveChange:= @ActiveChange;
 end;
 
@@ -84,6 +85,11 @@ begin
   Result := FLookup.LookupCache;
 end;
 
+function TDBLookupComboBox.GetNullValueKey: TShortCut;
+begin
+  result := FLookup.NullValueKey;
+end;
+
 procedure TDBLookupComboBox.SetKeyField(const Value: string);
 begin
   FLookup.KeyField:= Value;
@@ -122,4 +128,15 @@ begin
   ActiveChange(Self);
 end;
 
+procedure TDBLookupComboBox.SetNullValueKey(const AValue: TShortCut);
+begin
+  FLookup.NullValueKey := AValue;
+end;
+
+procedure TDBLookupComboBox.RemoveSelection(Sender: TObject);
+begin
+  ItemIndex := -1;
+  Text := '';
+end;
+
 

lcl/include/dblookuplistbox.inc

@@ -26,6 +26,7 @@ constructor TDBLookupListBox.Create(AOwner: TComponent);
 begin
   inherited Create(AOwner);
   FLookup:= TDBLookup.Create(Self);
+  FLookup.OnClearSelection := @RemoveSelection;
   FDataLink.OnActiveChange:= @ActiveChange;
 end;
 
@@ -97,6 +98,11 @@ begin
   Result := FLookup.LookupCache;
 end;
 
+function TDBLookupListBox.GetNullValueKey: TShortCut;
+begin
+  Result := FLookup.NullValueKey;
+end;
+
 procedure TDBLookupListBox.SetKeyField(const Value: string);
 begin
   FLookup.KeyField:= Value;
@@ -135,3 +141,17 @@ begin
   ActiveChange(Self);
 end;
 
+procedure TDBLookupListBox.RemoveSelection(Sender: TObject);
+begin
+  if not assigned(FDatalink.DataSet) or not FDatalink.DataSet.Active or
+     not assigned(FDatalink.Field) then
+  GetItemIndex; // a list-only dblookuplist do not automatically update itemindex
+
+  ItemIndex := -1;
+end;
+
+procedure TDBLookupListBox.SetNullValueKey(const AValue: TShortCut);
+begin
+  FLookup.NullValueKey := AValue;
+end;
+