Fix crash in relation manager

When clicking ok with invalid definitions.

Fixes #14869

src/app/qgsrelationadddlg.cpp

@@ -1,12 +1,36 @@
+/***************************************************************************
+  qgsrelationadddlg.cpp - QgsRelationAddDlg
+  ---------------------------------
+
+ begin                : 4.10.2013
+ copyright            : (C) 2013 by Matthias Kuhn
+ email                : matthias@opengis.ch
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
 #include "qgsrelationadddlg.h"
 #include "qgsvectorlayer.h"
 
+#include <QPushButton>
+
 QgsRelationAddDlg::QgsRelationAddDlg( QWidget *parent )
     : QDialog( parent )
 {
   setupUi( this );
 
   mTxtRelationId->setPlaceholderText( tr( "[Generated automatically]" ) );
+  checkDefinitionValid();
+
+  connect( mCbxReferencingLayer, SIGNAL( currentIndexChanged( int ) ), this, SLOT( checkDefinitionValid() ) );
+  connect( mCbxReferencingField, SIGNAL( currentIndexChanged( int ) ), this, SLOT( checkDefinitionValid() ) );
+  connect( mCbxReferencedLayer, SIGNAL( currentIndexChanged( int ) ), this, SLOT( checkDefinitionValid() ) );
+  connect( mCbxReferencedField, SIGNAL( currentIndexChanged( int ) ), this, SLOT( checkDefinitionValid() ) );
 }
 
 void QgsRelationAddDlg::addLayers( const QList< QgsVectorLayer* >& layers )
@@ -65,6 +89,14 @@ void QgsRelationAddDlg::on_mCbxReferencedLayer_currentIndexChanged( int index )
   loadLayerAttributes( mCbxReferencedField, mLayers[mCbxReferencedLayer->itemData( index ).toString()] );
 }
 
+void QgsRelationAddDlg::checkDefinitionValid()
+{
+  mButtonBox->button( QDialogButtonBox::Ok )->setEnabled( mCbxReferencedLayer->currentIndex() != -1
+      && mCbxReferencedField->currentIndex() != -1
+      && mCbxReferencingLayer->currentIndex() != -1
+      && mCbxReferencingField->currentIndex() != -1 );
+}
+
 void QgsRelationAddDlg::loadLayerAttributes( QComboBox* cbx, QgsVectorLayer* layer )
 {
   cbx->clear();

src/app/qgsrelationadddlg.h

@@ -40,6 +40,8 @@ class APP_EXPORT QgsRelationAddDlg : public QDialog, private Ui::QgsRelationAddD
     void on_mCbxReferencingLayer_currentIndexChanged( int index );
     void on_mCbxReferencedLayer_currentIndexChanged( int index );
 
+    void checkDefinitionValid();
+
   private:
     void loadLayerAttributes( QComboBox* cbx, QgsVectorLayer* layer );
 

src/ui/qgsrelationadddlgbase.ui

@@ -62,7 +62,7 @@
     </widget>
    </item>
    <item row="14" column="0" colspan="3">
-    <widget class="QDialogButtonBox" name="buttonBox">
+    <widget class="QDialogButtonBox" name="mButtonBox">
      <property name="orientation">
       <enum>Qt::Horizontal</enum>
      </property>
@@ -93,12 +93,12 @@
   <tabstop>mCbxReferencedLayer</tabstop>
   <tabstop>mCbxReferencedField</tabstop>
   <tabstop>mTxtRelationId</tabstop>
-  <tabstop>buttonBox</tabstop>
+  <tabstop>mButtonBox</tabstop>
  </tabstops>
  <resources/>
  <connections>
   <connection>
-   <sender>buttonBox</sender>
+   <sender>mButtonBox</sender>
    <signal>accepted()</signal>
    <receiver>QgsRelationAddDlgBase</receiver>
    <slot>accept()</slot>
@@ -114,7 +114,7 @@
    </hints>
   </connection>
   <connection>
-   <sender>buttonBox</sender>
+   <sender>mButtonBox</sender>
    <signal>rejected()</signal>
    <receiver>QgsRelationAddDlgBase</receiver>
    <slot>reject()</slot>