From b6a4657b66b23e23c65caa9667f514443bfa8fcd Mon Sep 17 00:00:00 2001
From: blikblum <blikblum@lazarus-ide.org>
Date: Mon, 24 Mar 2014 12:34:52 +0000
Subject: [PATCH] lcl: Reset TFieldDataLink when a key field changes. Issue
 #25876

git-svn-id: trunk@44505 -
---
 lcl/dbctrls.pp | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/lcl/dbctrls.pp b/lcl/dbctrls.pp
index 9348701c77..c5fac6f22c 100644
--- a/lcl/dbctrls.pp
+++ b/lcl/dbctrls.pp
@@ -52,6 +52,7 @@ Type
     FEditing: Boolean;
     IsModified: Boolean;
     function FieldCanModify: boolean;
+    function IsKeyField(aField: TField): Boolean;
     function GetCanModify: Boolean;
     // set current field
     procedure SetFieldName(const Value: string);
@@ -1379,6 +1380,25 @@ begin
     result := FField.CanModify;
 end;
 
+function TFieldDataLink.IsKeyField(aField: TField): Boolean;
+var
+  KeyFieldName, KeyFields: String;
+  StrPos: Integer;
+begin
+  KeyFields := FField.KeyFields;
+  StrPos := 1;
+  while StrPos <= Length(KeyFields) do
+  begin
+    KeyFieldName := ExtractFieldName(KeyFields, StrPos);
+    if SameText(aField.FieldName, KeyFieldName) then
+    begin
+      Result := True;
+      Exit;
+    end;
+  end;
+  Result := False;
+end;
+
 {TFieldDataLink  Private Methods}
 {
   If the field exists and can be modified, then
@@ -1529,7 +1549,8 @@ end;
 }
 procedure TFieldDataLink.RecordChanged(aField: TField);
 begin
-  if (aField = nil) or (aField = FField) then
+  if (aField = nil) or (aField = FField) or
+   ((FField <> nil) and (FField.FieldKind = fkLookup) and IsKeyField(aField)) then
     Reset;
 end;