An error message is displayed when an auxiliary layer cannot be created (3.16 backport)

src/core/qgsauxiliarystorage.cpp

@@ -587,7 +587,7 @@ QgsAuxiliaryLayer *QgsAuxiliaryStorage::createAuxiliaryLayer( const QgsField &fi
 
     if ( !tableExists( table, database.get() ) )
     {
-      if ( !createTable( field.typeName(), table, database.get() ) )
+      if ( !createTable( field.typeName(), table, database.get(), mErrorString ) )
       {
         return alayer;
       }
@@ -702,25 +702,24 @@ bool QgsAuxiliaryStorage::exec( const QString &sql, sqlite3 *handler )
   return rc;
 }
 
-void QgsAuxiliaryStorage::debugMsg( const QString &sql, sqlite3 *handler )
+QString QgsAuxiliaryStorage::debugMsg( const QString &sql, sqlite3 *handler )
 {
-#ifdef QGISDEBUG
   const QString err = QString::fromUtf8( sqlite3_errmsg( handler ) );
   const QString msg = QObject::tr( "Unable to execute" );
   const QString errMsg = QObject::tr( "%1 '%2': %3" ).arg( msg, sql, err );
   QgsDebugMsg( errMsg );
-#else
-  Q_UNUSED( sql )
-  Q_UNUSED( handler )
-#endif
+  return errMsg;
 }
 
-bool QgsAuxiliaryStorage::createTable( const QString &type, const QString &table, sqlite3 *handler )
+bool QgsAuxiliaryStorage::createTable( const QString &type, const QString &table, sqlite3 *handler, QString &errorMsg )
 {
   const QString sql = QStringLiteral( "CREATE TABLE IF NOT EXISTS '%1' ( '%2' %3  )" ).arg( table, AS_JOINFIELD, type );
 
   if ( !exec( sql, handler ) )
+  {
+    errorMsg = QgsAuxiliaryStorage::debugMsg( sql, handler );
     return false;
+  }
 
   return true;
 }

src/core/qgsauxiliarystorage.h

@@ -413,18 +413,18 @@ class CORE_EXPORT QgsAuxiliaryStorage
     static spatialite_database_unique_ptr createDB( const QString &filename );
     static spatialite_database_unique_ptr openDB( const QString &filename );
     static bool tableExists( const QString &table, sqlite3 *handler );
-    static bool createTable( const QString &type, const QString &table, sqlite3 *handler );
+    static bool createTable( const QString &type, const QString &table, sqlite3 *handler, QString &errorMsg );
 
     static bool exec( const QString &sql, sqlite3 *handler );
-    static void debugMsg( const QString &sql, sqlite3 *handler );
+    static QString debugMsg( const QString &sql, sqlite3 *handler );
 
     static QgsDataSourceUri parseOgrUri( const QgsDataSourceUri &uri );
 
     bool mValid = false;
     QString mFileName; // original filename
     QString mTmpFileName; // temporary filename used in copy mode
     bool mCopy = false;
-    QString mErrorString;
+    mutable QString mErrorString;
 };
 
 #endif

src/gui/qgsnewauxiliarylayerdialog.cpp

@@ -54,6 +54,13 @@ void QgsNewAuxiliaryLayerDialog::accept()
       mLayer->setAuxiliaryLayer( alayer );
     }
   }
+  else
+  {
+    QDialog::close();
+    const QString errMsg = QgsProject::instance()->auxiliaryStorage()->errorString();
+    QMessageBox::critical( this, tr( "New Auxiliary Layer" ), errMsg );
+    return;
+  }
 
   QDialog::accept();
 }

tests/src/python/test_qgsauxiliarystorage.py

@@ -26,6 +26,7 @@
                        QgsPalLayerSettings,
                        QgsSymbolLayer,
                        QgsVectorLayerSimpleLabeling,
+                       QgsField,
                        NULL)
 from qgis.testing import start_app, unittest
 from utilities import unitTestDataPath, writeShape
@@ -477,6 +478,27 @@ def testQgdCreation(self):
         qgd = newpath + '.qgd'
         self.assertTrue(os.path.exists(qgd))
 
+    def testInvalidPrimaryKey(self):
+        # create layer
+        vl = QgsVectorLayer(
+            'Point?crs=epsg:4326&field=pk:integer&key=pk',
+            'test', 'memory')
+        assert (vl.isValid())
+
+        # add a field with an invalid typename
+        field = QgsField(name="invalid_pk", type=QVariant.Int, typeName="xsd:int")
+        vl.startEditing()
+        vl.addAttribute(field)
+        vl.commitChanges()
+
+        # create auxiliary storage based on the invalid field
+        s = QgsAuxiliaryStorage()
+        pkf = vl.fields().field(vl.fields().indexOf('invalid_pk'))
+        al = s.createAuxiliaryLayer(pkf, vl)
+
+        self.assertEqual(al, None)
+        self.assertTrue("CREATE TABLE IF NOT EXISTS" in s.errorString())
+
 
 if __name__ == '__main__':
     unittest.main()