Fixes in the QgsPolymorphicRelation

qgis · Jan 12, 2021 · 89c07ff · 89c07ff
1 parent 7feb073
commit 89c07ff
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Showing 3 changed files with 30 additions and 22 deletions.
diff --git a/python/core/auto_generated/qgspolymorphicrelation.sip.in b/python/core/auto_generated/qgspolymorphicrelation.sip.in
@@ -207,11 +207,6 @@ Sets the ``expression`` to identify the parent layer
     QString referencedLayerExpression() const;
 %Docstring
 Returns the expression to identify the parent layer
-%End
-
-    QgsExpressionContext getLayerContext() const;
-%Docstring
-Provide layer metadata as variables in an expression context
 %End
 
     void setReferencedLayerIds( const QStringList &childRelationIds );
@@ -227,6 +222,11 @@ Returns a list of layer ids to be used as potential referenced layers
     QList<QgsRelation> getGeneratedRelations() const;
 %Docstring
 Returns a list of generated relations, based on the currently set :py:func:`~QgsPolymorphicRelation.referencedLayerIds`
+%End
+
+    QString layerRepresentation( const QgsVectorLayer *layer ) const;
+%Docstring
+Returns layer representation as evaluated string
 %End
 
 };

diff --git a/src/core/qgspolymorphicrelation.cpp b/src/core/qgspolymorphicrelation.cpp
@@ -21,6 +21,7 @@
 #include "qgsproject.h"
 #include "qgsvectorlayer.h"
 #include "qgspolymorphicrelation_p.h"
+#include "qgsexpressioncontextutils.h"
 
 QgsPolymorphicRelation::QgsPolymorphicRelation()
   : d( new QgsPolymorphicRelationPrivate() )
@@ -225,20 +226,21 @@ bool QgsPolymorphicRelation::hasEqualDefinition( const QgsPolymorphicRelation &o
 
 void QgsPolymorphicRelation::updateRelationStatus()
 {
+  const QMap<QString, QgsMapLayer *> &mapLayers = mContext.project()->mapLayers();
+
+  d->mValid = true;
+  d->mReferencingLayer = mapLayers.contains( d->mReferencingLayerId )
+                         ? qobject_cast<QgsVectorLayer *>( mapLayers[d->mReferencingLayerId] )
+                         : nullptr;
+  d->mReferencedLayersMap.clear();
+
   if ( d->mRelationId.isEmpty() )
   {
     QgsDebugMsg( QStringLiteral( "Invalid relation: no ID" ) );
     d->mValid = false;
     return;
   }
 
-  const QMap<QString, QgsMapLayer *> &mapLayers = mContext.project()->mapLayers();
-
-  d->mValid = true;
-  d->mReferencingLayer = qobject_cast<QgsVectorLayer *>( mapLayers[d->mReferencingLayerId] );
-  // TODO probably this map is not needed??
-  d->mReferencedLayersMap.clear();
-
   if ( !d->mReferencingLayer )
   {
     QgsDebugMsgLevel( QStringLiteral( "Invalid relation: referencing layer does not exist. ID: %1" ).arg( d->mReferencingLayerId ), 4 );
@@ -355,11 +357,6 @@ QStringList QgsPolymorphicRelation::referencedLayerIds() const
   return d->mReferencedLayerIds;
 }
 
-QgsExpressionContext QgsPolymorphicRelation::getLayerContext() const
-{
-  return QgsExpressionContext();
-}
-
 QList<QgsRelation> QgsPolymorphicRelation::getGeneratedRelations() const
 {
   QList<QgsRelation> relations;
@@ -391,3 +388,14 @@ QList<QgsRelation> QgsPolymorphicRelation::getGeneratedRelations() const
 
   return relations;
 }
+
+QString QgsPolymorphicRelation::layerRepresentation( const QgsVectorLayer *layer ) const
+{
+  if ( !layer || !layer->isValid() )
+    return QString();
+
+  QgsExpressionContext context = layer->createExpressionContext();
+  QgsExpression expr( d->mReferencedLayerExpression );
+
+  return expr.evaluate( &context ).toString();
+}
diff --git a/src/core/qgspolymorphicrelation.h b/src/core/qgspolymorphicrelation.h
@@ -254,11 +254,6 @@ class CORE_EXPORT QgsPolymorphicRelation
       */
     QString referencedLayerExpression() const;
 
-    /**
-     * Provide layer metadata as variables in an expression context
-     */
-    QgsExpressionContext getLayerContext() const;
-
     /**
      * Sets a list of layer ids to be used as potential referenced layers
      */
@@ -274,6 +269,11 @@ class CORE_EXPORT QgsPolymorphicRelation
      */
     QList<QgsRelation> getGeneratedRelations() const;
 
+    /**
+     * Returns layer representation as evaluated string
+     */
+    QString layerRepresentation( const QgsVectorLayer *layer ) const;
+
   private:
 
     mutable QExplicitlySharedDataPointer<QgsPolymorphicRelationPrivate> d;