Add QgsRelation::getReferencedFeature to access parent feature

python/core/qgsrelation.sip

@@ -118,13 +118,22 @@ class QgsRelation
      */
     QgsFeatureRequest getRelatedFeaturesRequest( const QgsFeature& feature ) const;
 
-    const QString name() const;
+    QgsFeatureRequest getReferencedFeatureRequest( const QgsFeature& feature ) const;
+
+    QgsFeature getReferencedFeature( const QgsFeature& child ) const;
 
     /**
      * The id
      * @return
      */
-    const QString& id() const;
+    QString name() const;
+
+    /**
+     * A (project-wide) unique id for this relation
+     *
+     * @return The id
+     */
+    QString id() const;
 
     /**
      * Access the referencing (child) layer's id
@@ -182,5 +191,4 @@ class QgsRelation
 
   protected:
     void updateRelationStatus();
-    void runChecks();
 };

src/core/qgsrelation.cpp

@@ -97,7 +97,7 @@ void QgsRelation::writeXML( QDomNode &node, QDomDocument &doc ) const
   elem.setAttribute( "referencingLayer", mReferencingLayerId );
   elem.setAttribute( "referencedLayer", mReferencedLayerId );
 
-  foreach ( FieldPair fields, mFieldPairs )
+  Q_FOREACH ( FieldPair fields, mFieldPairs )
   {
     QDomElement referenceElem = doc.createElement( "fieldRef" );
     referenceElem.setAttribute( "referencingField", fields.first );
@@ -153,22 +153,20 @@ QgsFeatureRequest QgsRelation::getRelatedFeaturesRequest( const QgsFeature& feat
 {
   QStringList conditions;
 
-  foreach ( const QgsRelation::FieldPair& fieldPair, mFieldPairs )
+  Q_FOREACH ( const QgsRelation::FieldPair& fieldPair, mFieldPairs )
   {
     int referencingIdx = referencingLayer()->pendingFields().indexFromName( fieldPair.referencingField() );
     QgsField referencingField = referencingLayer()->pendingFields().at( referencingIdx );
 
-    switch ( referencingField.type() )
+    if ( referencingField.type() == QVariant::String )
     {
-      case QVariant::String:
+      // Use quotes
-        // Use quotes
+      conditions << QString( "\"%1\" = '%2'" ).arg( fieldPair.referencingField(), feature.attribute( fieldPair.referencedField() ).toString() );
-        conditions << QString( "\"%1\" = '%2'" ).arg( fieldPair.referencingField(), feature.attribute( fieldPair.referencedField() ).toString() );
+    }
-        break;
+    else
-
+    {
-      default:
+      // No quotes
-        // No quotes
+      conditions << QString( "\"%1\" = %2" ).arg( fieldPair.referencingField(), feature.attribute( fieldPair.referencedField() ).toString() );
-        conditions << QString( "\"%1\" = %2" ).arg( fieldPair.referencingField(), feature.attribute( fieldPair.referencedField() ).toString() );
-        break;
     }
   }
 
@@ -181,12 +179,58 @@ QgsFeatureRequest QgsRelation::getRelatedFeaturesRequest( const QgsFeature& feat
   return myRequest;
 }
 
-const QString QgsRelation::name() const
+QgsFeatureRequest QgsRelation::getReferencedFeatureRequest( const QgsAttributes& attributes ) const
+{
+  QStringList conditions;
+
+  Q_FOREACH ( const QgsRelation::FieldPair& fieldPair, mFieldPairs )
+  {
+    int referencedIdx = referencedLayer()->pendingFields().indexFromName( fieldPair.referencedField() );
+    int referencingIdx = referencingLayer()->pendingFields().indexFromName( fieldPair.referencingField() );
+
+    QgsField referencedField = referencedLayer()->pendingFields().at( referencedIdx );
+
+    if ( referencedField.type() == QVariant::String )
+    {
+      // Use quotes
+      conditions << QString( "\"%1\" = '%2'" ).arg( fieldPair.referencedField(), attributes[referencingIdx].toString() );
+    }
+    else
+    {
+      // No quotes
+      conditions << QString( "\"%1\" = %2" ).arg( fieldPair.referencedField(), attributes[referencingIdx].toString() );
+    }
+  }
+
+  QgsFeatureRequest myRequest;
+
+  QgsDebugMsg( QString( "Filter conditions: '%1'" ).arg( conditions.join( " AND " ) ) );
+
+  myRequest.setFilterExpression( conditions.join( " AND " ) );
+
+  return myRequest;
+}
+
+QgsFeatureRequest QgsRelation::getReferencedFeatureRequest( const QgsFeature& feature ) const
+{
+  return getReferencedFeatureRequest( feature.attributes() );
+}
+
+QgsFeature QgsRelation::getReferencedFeature( const QgsFeature& child ) const
+{
+  QgsFeatureRequest request = getReferencedFeatureRequest( child );
+
+  QgsFeature f;
+  mReferencedLayer->getFeatures( request ).nextFeature( f );
+  return f;
+}
+
+QString QgsRelation::name() const
 {
   return mRelationName;
 }
 
-const QString& QgsRelation::id() const
+QString QgsRelation::id() const
 {
   return mRelationId;
 }
@@ -251,8 +295,3 @@ void QgsRelation::updateRelationStatus()
     }
   }
 }
-
-void QgsRelation::runChecks()
-{
-
-}

src/core/qgsrelation.h

@@ -138,17 +138,55 @@ class CORE_EXPORT QgsRelation
      *
      * @param feature A feature from the referenced (parent) layer
      *
-     * @return An request for all the referenced features
+     * @return A request for all the referencing features
      */
     QgsFeatureRequest getRelatedFeaturesRequest( const QgsFeature& feature ) const;
 
-    const QString name() const;
+    /**
+     * Creates a request to return the feature on the referenced (parent) layer
+     * which is referenced by the provided feature.
+     *
+     * @param attributes An attribute vector containing the foreign key
+     *
+     * @return A request the referenced feature
+     */
+    QgsFeatureRequest getReferencedFeatureRequest( const QgsAttributes& attributes ) const;
 
     /**
-     * The id
+     * Creates a request to return the feature on the referenced (parent) layer
-     * @return
+     * which is referenced by the provided feature.
+     *
+     * @param feature A feature from the referencing (child) layer
+     *
+     * @return A request the referenced feature
      */
-    const QString& id() const;
+    QgsFeatureRequest getReferencedFeatureRequest( const QgsFeature& feature ) const;
+
+    /**
+     * Creates a request to return the feature on the referenced (parent) layer
+     * which is referenced by the provided feature.
+     *
+     * @param feature A feature from the referencing (child) layer
+     *
+     * @return A request the referenced feature
+     */
+    QgsFeature getReferencedFeature( const QgsFeature& child ) const;
+
+    /**
+     * Returns a human readable name for this relation. Mostly used as title for the children.
+     *
+     * @see id()
+     *
+     * @return A name
+     */
+    QString name() const;
+
+    /**
+     * A (project-wide) unique id for this relation
+     *
+     * @return The id
+     */
+    QString id() const;
 
     /**
      * Access the referencing (child) layer's id
@@ -198,7 +236,6 @@ class CORE_EXPORT QgsRelation
 
   protected:
     void updateRelationStatus();
-    void runChecks();
 
   private:
     /** Unique Id */

tests/src/python/test_qgsrelation.py

@@ -25,110 +25,122 @@ from utilities import (getQgisTestApp,
                        TestCase,
                        unittest
                        )
+
 QGISAPP, CANVAS, IFACE, PARENT = getQgisTestApp()
 
+
 def createReferencingLayer():
     layer = QgsVectorLayer("Point?field=fldtxt:string&field=foreignkey:integer",
                            "referencinglayer", "memory")
     pr = layer.dataProvider()
     f1 = QgsFeature()
-    f1.setFields( layer.pendingFields() )
+    f1.setFields(layer.pendingFields())
     f1.setAttributes(["test1", 123])
-    f1.setGeometry(QgsGeometry.fromPoint(QgsPoint(100,200)))
+    f1.setGeometry(QgsGeometry.fromPoint(QgsPoint(100, 200)))
     f2 = QgsFeature()
-    f2.setFields( layer.pendingFields() )
+    f2.setFields(layer.pendingFields())
     f2.setAttributes(["test2", 123])
-    f2.setGeometry(QgsGeometry.fromPoint(QgsPoint(101,201)))
+    f2.setGeometry(QgsGeometry.fromPoint(QgsPoint(101, 201)))
-    assert pr.addFeatures([f1,f2])
+    assert pr.addFeatures([f1, f2])
     return layer
 
+
 def createReferencedLayer():
     layer = QgsVectorLayer(
         "Point?field=x:string&field=y:integer&field=z:integer",
         "referencedlayer", "memory")
     pr = layer.dataProvider()
     f1 = QgsFeature()
-    f1.setFields( layer.pendingFields() )
+    f1.setFields(layer.pendingFields())
     f1.setAttributes(["foo", 123, 321])
-    f1.setGeometry(QgsGeometry.fromPoint(QgsPoint(1,1)))
+    f1.setGeometry(QgsGeometry.fromPoint(QgsPoint(1, 1)))
     f2 = QgsFeature()
-    f2.setFields( layer.pendingFields() )
+    f2.setFields(layer.pendingFields())
     f2.setAttributes(["bar", 456, 654])
-    f2.setGeometry(QgsGeometry.fromPoint(QgsPoint(2,2)))
+    f2.setGeometry(QgsGeometry.fromPoint(QgsPoint(2, 2)))
     f3 = QgsFeature()
-    f3.setFields( layer.pendingFields() )
+    f3.setFields(layer.pendingFields())
     f3.setAttributes(["foobar", 789, 554])
-    f3.setGeometry(QgsGeometry.fromPoint(QgsPoint(2,3)))
+    f3.setGeometry(QgsGeometry.fromPoint(QgsPoint(2, 3)))
     assert pr.addFeatures([f1, f2, f3])
     return layer
 
-def formatAttributes(attrs):
-    return repr([ unicode(a) for a in attrs ])
 
-class TestQgsRelation( TestCase ):
+def formatAttributes(attrs):
+    return repr([unicode(a) for a in attrs])
+
+
+class TestQgsRelation(TestCase):
+    def setUp(self):
+        self.referencedLayer = createReferencedLayer()
+        self.referencingLayer = createReferencingLayer()
+        QgsMapLayerRegistry.instance().addMapLayers([self.referencedLayer, self.referencingLayer])
+
+    def tearDown(self):
+        QgsMapLayerRegistry.instance().removeAllMapLayers()
 
     def test_isValid(self):
-        referencedLayer = createReferencedLayer()
-        referencingLayer = createReferencingLayer()
-        QgsMapLayerRegistry.instance().addMapLayers([referencedLayer,referencingLayer])
 
         rel = QgsRelation()
         assert not rel.isValid()
 
-        rel.setRelationId( 'rel1' )
+        rel.setRelationId('rel1')
         assert not rel.isValid()
 
-        rel.setRelationName( 'Relation Number One' )
+        rel.setRelationName('Relation Number One')
         assert not rel.isValid()
 
-        rel.setReferencingLayer( referencingLayer.id() )
+        rel.setReferencingLayer(self.referencingLayer.id())
         assert not rel.isValid()
 
-        rel.setReferencedLayer( referencedLayer.id() )
+        rel.setReferencedLayer(self.referencedLayer.id())
         assert not rel.isValid()
 
-        rel.addFieldPair( 'foreignkey', 'y' )
+        rel.addFieldPair('foreignkey', 'y')
         assert rel.isValid()
 
-        QgsMapLayerRegistry.instance().removeAllMapLayers()
 
     def test_getRelatedFeatures(self):
-        referencedLayer = createReferencedLayer()
-        referencingLayer = createReferencingLayer()
-        QgsMapLayerRegistry.instance().addMapLayers([referencedLayer,referencingLayer])
-
         rel = QgsRelation()
 
-        rel.setRelationId( 'rel1' )
+        rel.setRelationId('rel1')
-        rel.setRelationName( 'Relation Number One' )
+        rel.setRelationName('Relation Number One')
-        rel.setReferencingLayer( referencingLayer.id() )
+        rel.setReferencingLayer(self.referencingLayer.id())
-        rel.setReferencedLayer( referencedLayer.id() )
+        rel.setReferencedLayer(self.referencedLayer.id())
-        rel.addFieldPair( 'foreignkey', 'y' )
+        rel.addFieldPair('foreignkey', 'y')
 
-        feat = referencedLayer.getFeatures().next()
+        feat = self.referencedLayer.getFeatures().next()
 
-        it = rel.getRelatedFeatures( feat )
+        it = rel.getRelatedFeatures(feat)
 
-        [ a.attributes() for a in it ] == [[u'test1', 123], [u'test2', 123]]
+        assert [a.attributes() for a in it] == [[u'test1', 123], [u'test2', 123]]
+
+    def test_getReferencedFeature(self):
+        rel = QgsRelation()
+        rel.setRelationId('rel1')
+        rel.setRelationName('Relation Number One')
+        rel.setReferencingLayer(self.referencingLayer.id())
+        rel.setReferencedLayer(self.referencedLayer.id())
+        rel.addFieldPair('foreignkey', 'y')
+
+        feat = self.referencingLayer.getFeatures().next()
+
+        f = rel.getReferencedFeature(feat)
+
+        assert f.isValid()
+        assert f[0] == 'foo'
 
-        QgsMapLayerRegistry.instance().removeAllMapLayers()
 
     def test_fieldPairs(self):
-        referencedLayer = createReferencedLayer()
-        referencingLayer = createReferencingLayer()
-        QgsMapLayerRegistry.instance().addMapLayers([referencedLayer,referencingLayer])
-
         rel = QgsRelation()
 
-        rel.setRelationId( 'rel1' )
+        rel.setRelationId('rel1')
-        rel.setRelationName( 'Relation Number One' )
+        rel.setRelationName('Relation Number One')
-        rel.setReferencingLayer( referencingLayer.id() )
+        rel.setReferencingLayer(self.referencingLayer.id())
-        rel.setReferencedLayer( referencedLayer.id() )
+        rel.setReferencedLayer(self.referencedLayer.id())
-        rel.addFieldPair( 'foreignkey', 'y' )
+        rel.addFieldPair('foreignkey', 'y')
 
-        assert( rel.fieldPairs() == { 'foreignkey': 'y'} )
+        assert (rel.fieldPairs() == {'foreignkey': 'y'})
-
-        QgsMapLayerRegistry.instance().removeAllMapLayers()
 
 
 if __name__ == '__main__':