Fix style constraint save when strength is NotSet

Fix #58431 I feel that the underlying issue remains (which is that setting the strength to NotSet removes it from the field but not from the layer and that the default strength is Hard) but since it was clearly made in purpose 8 years ago I am not keen to change it lightly.
qgis · Oct 7, 2024 · df947ef · df947ef
1 parent fefba6c
commit df947ef
Show file tree

Hide file tree

Showing 2 changed files with 76 additions and 4 deletions.
diff --git a/src/core/vector/qgsvectorlayer.cpp b/src/core/vector/qgsvectorlayer.cpp
@@ -3141,10 +3141,53 @@ bool QgsVectorLayer::writeSymbology( QDomNode &node, QDomDocument &doc, QString
     {
       QDomElement constraintElem = doc.createElement( QStringLiteral( "constraint" ) );
       constraintElem.setAttribute( QStringLiteral( "field" ), field.name() );
-      constraintElem.setAttribute( QStringLiteral( "constraints" ), field.constraints().constraints() );
-      constraintElem.setAttribute( QStringLiteral( "unique_strength" ), field.constraints().constraintStrength( QgsFieldConstraints::ConstraintUnique ) );
-      constraintElem.setAttribute( QStringLiteral( "notnull_strength" ), field.constraints().constraintStrength( QgsFieldConstraints::ConstraintNotNull ) );
-      constraintElem.setAttribute( QStringLiteral( "exp_strength" ), field.constraints().constraintStrength( QgsFieldConstraints::ConstraintExpression ) );
+
+      // This manipulation is required because when the strength is set to NotSet the constraint is removed from
+      // the field but when the field is queried for the strength of a not-existing constraint it returns Hard by default,
+      // see issue #58431
+      QgsFieldConstraints::Constraints constraints { mFieldConstraints.value( field.name() ) };
+      QgsFieldConstraints::ConstraintStrength uniqueStrength { QgsFieldConstraints::ConstraintStrength::ConstraintStrengthNotSet };
+      QgsFieldConstraints::ConstraintStrength notNullStrength { QgsFieldConstraints::ConstraintStrength::ConstraintStrengthNotSet };
+      QgsFieldConstraints::ConstraintStrength expressionStrength { QgsFieldConstraints::ConstraintStrength::ConstraintStrengthNotSet };
+
+      QPair<QString, QgsFieldConstraints::Constraint> strengthKey { qMakePair( field.name(), QgsFieldConstraints::ConstraintUnique ) };
+
+      if ( mFieldConstraintStrength.contains( strengthKey ) && mFieldConstraintStrength.value( strengthKey ) == QgsFieldConstraints::ConstraintStrength::ConstraintStrengthNotSet )
+      {
+        constraints.setFlag( QgsFieldConstraints::Constraint::ConstraintUnique, false );
+      }
+      else
+      {
+        uniqueStrength = mFieldConstraintStrength.value( strengthKey );
+      }
+
+      strengthKey = qMakePair( field.name(), QgsFieldConstraints::ConstraintNotNull );
+
+      if ( mFieldConstraintStrength.contains( strengthKey ) && mFieldConstraintStrength.value( strengthKey ) == QgsFieldConstraints::ConstraintStrength::ConstraintStrengthNotSet )
+      {
+        constraints.setFlag( QgsFieldConstraints::Constraint::ConstraintNotNull, false );
+      }
+      else
+      {
+        notNullStrength = mFieldConstraintStrength.value( strengthKey );
+      }
+
+      strengthKey = qMakePair( field.name(), QgsFieldConstraints::ConstraintExpression );
+
+      if ( mFieldConstraintStrength.contains( strengthKey ) && mFieldConstraintStrength.value( strengthKey ) == QgsFieldConstraints::ConstraintStrength::ConstraintStrengthNotSet )
+      {
+        constraints.setFlag( QgsFieldConstraints::Constraint::ConstraintExpression, false );
+      }
+      else
+      {
+        expressionStrength = mFieldConstraintStrength.value( strengthKey );
+      }
+
+
+      constraintElem.setAttribute( QStringLiteral( "constraints" ), constraints );
+      constraintElem.setAttribute( QStringLiteral( "unique_strength" ), uniqueStrength );
+      constraintElem.setAttribute( QStringLiteral( "notnull_strength" ), notNullStrength );
+      constraintElem.setAttribute( QStringLiteral( "exp_strength" ), expressionStrength );
       constraintsElem.appendChild( constraintElem );
     }
     node.appendChild( constraintsElem );

diff --git a/tests/src/python/test_qgsvectorlayer.py b/tests/src/python/test_qgsvectorlayer.py
@@ -4675,6 +4675,35 @@ def test_selection_properties(self):
             self.assertEqual(vl2.selectionProperties().selectionColor(),
                              QColor(255, 0, 0))
 
+    def testConstraintsStrengthNotSet(self):
+        """Test issue GH #58431 when strength NotSet becomes Hard"""
+
+        # Create a memory layer with unique constraints
+        layer = QgsVectorLayer("Point?field=fldtxt:string&field=fldint:integer", "test_unique", "memory")
+        self.assertTrue(layer.isValid())
+
+        # Se not constraint on fldtxt
+        layer.setFieldConstraint(0, QgsFieldConstraints.Constraint.ConstraintNotNull, QgsFieldConstraints.ConstraintStrength.ConstraintStrengthSoft)
+        layer.setFieldConstraint(0, QgsFieldConstraints.Constraint.ConstraintUnique, QgsFieldConstraints.ConstraintStrength.ConstraintStrengthNotSet)
+
+        # Export the style to QML
+        style = QgsMapLayerStyle()
+        temp_file = tempfile.mktemp(suffix='.qml')
+        layer.saveNamedStyle(temp_file)
+        layer.loadNamedStyle(temp_file)
+
+        # Check constraints at the field level
+        field = layer.fields().at(0)
+        constraints = field.constraints()
+        self.assertEqual(constraints.constraintStrength(QgsFieldConstraints.Constraint.ConstraintNotNull), QgsFieldConstraints.ConstraintStrength.ConstraintStrengthSoft)
+        self.assertEqual(constraints.constraintStrength(QgsFieldConstraints.Constraint.ConstraintUnique), QgsFieldConstraints.ConstraintStrength.ConstraintStrengthNotSet)
+
+        # Check constraints at the layer level
+        constraints = layer.fieldConstraintsAndStrength(0)
+        self.assertEqual(constraints[QgsFieldConstraints.Constraint.ConstraintNotNull], QgsFieldConstraints.ConstraintStrength.ConstraintStrengthSoft)
+        self.assertEqual(constraints[QgsFieldConstraints.Constraint.ConstraintUnique], QgsFieldConstraints.ConstraintStrength.ConstraintStrengthNotSet)
+
+
 # TODO:
 # - fetch rect: feat with changed geometry: 1. in rect, 2. out of rect
 # - more join tests