Merge pull request #45841 from 3nids/fix-rel-mismatch-type

improve success of compiled expressions running on backend with mismatching types in relation field pairs

python/core/auto_generated/expression/qgsexpression.sip.in

@@ -673,13 +673,14 @@ length, and presents text representations of non numeric/text types (e.g., geome
 .. versionadded:: 2.14
 %End
 
-    static QString createFieldEqualityExpression( const QString &fieldName, const QVariant &value );
+    static QString createFieldEqualityExpression( const QString &fieldName, const QVariant &value, QVariant::Type fieldType = QVariant::Type::Invalid );
 %Docstring
 Create an expression allowing to evaluate if a field is equal to a
 value. The value may be null.
 
 :param fieldName: the name of the field
 :param value: the value of the field
+:param fieldType: the type of the field on the left side used to quote the value. If not given, the value type is used instead
 
 :return: the expression to evaluate field equality
 

src/core/expression/qgsexpression.cpp

@@ -1112,14 +1112,16 @@ QString QgsExpression::formatPreviewString( const QVariant &value, const bool ht
   }
 }
 
-QString QgsExpression::createFieldEqualityExpression( const QString &fieldName, const QVariant &value )
+QString QgsExpression::createFieldEqualityExpression( const QString &fieldName, const QVariant &value, QVariant::Type fieldType )
 {
   QString expr;
 
   if ( value.isNull() )
     expr = QStringLiteral( "%1 IS NULL" ).arg( quotedColumnRef( fieldName ) );
-  else
+  else if ( fieldType == QVariant::Type::Invalid )
     expr = QStringLiteral( "%1 = %2" ).arg( quotedColumnRef( fieldName ), quotedValue( value ) );
+  else
+    expr = QStringLiteral( "%1 = %2" ).arg( quotedColumnRef( fieldName ), quotedValue( value, fieldType ) );
 
   return expr;
 }

src/core/expression/qgsexpression.h

@@ -659,10 +659,11 @@ class CORE_EXPORT QgsExpression
      *  value. The value may be null.
      * \param fieldName the name of the field
      * \param value the value of the field
+     * \param fieldType the type of the field on the left side used to quote the value. If not given, the value type is used instead
      * \returns the expression to evaluate field equality
      * \since QGIS 3.0
      */
-    static QString createFieldEqualityExpression( const QString &fieldName, const QVariant &value );
+    static QString createFieldEqualityExpression( const QString &fieldName, const QVariant &value, QVariant::Type fieldType = QVariant::Type::Invalid );
 
     /**
      * Returns TRUE if the given \a expression is a simple "field=value" type expression.

src/core/qgsrelation.cpp

@@ -221,7 +221,16 @@ QString QgsRelation::getRelatedFeaturesFilter( const QgsFeature &feature ) const
   for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
   {
     QVariant val( feature.attribute( pair.referencedField() ) );
-    conditions << QgsExpression::createFieldEqualityExpression( pair.referencingField(), val );
+    int referencingIdx = referencingLayer()->fields().lookupField( pair.referencingField() );
+    if ( referencingIdx >= 0 )
+    {
+      QVariant::Type fieldType = referencingLayer()->fields().at( referencingIdx ).type();
+      conditions << QgsExpression::createFieldEqualityExpression( pair.referencingField(), val, fieldType );
+    }
+    else
+    {
+      conditions << QgsExpression::createFieldEqualityExpression( pair.referencingField(), val );
+    }
   }
 
   return conditions.join( QLatin1String( " AND " ) );
@@ -233,8 +242,17 @@ QgsFeatureRequest QgsRelation::getReferencedFeatureRequest( const QgsAttributes
 
   for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
   {
+    int referencedIdx = referencedLayer()->fields().lookupField( pair.referencedField() );
     int referencingIdx = referencingLayer()->fields().lookupField( pair.referencingField() );
-    conditions << QgsExpression::createFieldEqualityExpression( pair.referencedField(), attributes.at( referencingIdx ) );
+    if ( referencedIdx >= 0 )
+    {
+      QVariant::Type fieldType = referencedLayer()->fields().at( referencedIdx ).type();
+      conditions << QgsExpression::createFieldEqualityExpression( pair.referencedField(), attributes.at( referencingIdx ), fieldType );
+    }
+    else
+    {
+      conditions << QgsExpression::createFieldEqualityExpression( pair.referencedField(), attributes.at( referencingIdx ) );
+    }
   }
 
   QgsFeatureRequest myRequest;

tests/src/python/test_qgsexpression.py

@@ -271,6 +271,20 @@ class TestQgsExpressionCustomFunctions(unittest.TestCase):
         res = '"my\'field" = TRUE'
         self.assertEqual(e.createFieldEqualityExpression(field, value), res)
 
+        # test with field type
+        field = "myfield"
+        value = 1
+        type = QVariant.String
+        res = '"myfield" = \'1\''
+        self.assertEqual(e.createFieldEqualityExpression(field, value, type), res)
+
+        # test with field type
+        field = "myfield"
+        value = "1"
+        type = QVariant.Int
+        res = '"myfield" = 1'
+        self.assertEqual(e.createFieldEqualityExpression(field, value, type), res)
+
     def testReferencedAttributeIndexesNonExistingField(self):
         e = QgsExpression()
         e.setExpression("foo = 1")