Add shorthands to get features by fid, fids and expression

m-kuhn · m-kuhn · commit d91a45ceaf7e · 2016-07-19T10:37:09.000+02:00
Adds new methods overloads to QgsVectorLayer

  getFeatures( expression )
  getFeatures( ids )
  getFeature( id )

These three methods to query features are by far the most used ones
and with this patch it is much easier to write and read code.
diff --git a/python/core/qgsvectorlayer.sip b/python/core/qgsvectorlayer.sip
@@ -616,6 +616,22 @@ class QgsVectorLayer : QgsMapLayer
      */
     QgsFeatureIterator getFeatures( const QgsFeatureRequest& request = QgsFeatureRequest() ) const;
 
+    /**
+     * Query the provider for features matching a given expression.
+     */
+    QgsFeatureIterator getFeatures( const QString& expression );
+
+    /**
+     * Query the provider for the feature with the given id.
+     * If there is no such feature, the returned feature will be invalid.
+     */
+    QgsFeature getFeature( QgsFeatureId fid );
+
+    /**
+     * Query the provider for the features with the given ids.
+     */
+    QgsFeatureIterator getFeatures( QgsFeatureIds fids );
+
     /** Adds a feature
         @param f feature to add
         @param alsoUpdateExtent If True, will also go to the effort of e.g. updating the extents.
diff --git a/src/core/qgsfeaturerequest.cpp b/src/core/qgsfeaturerequest.cpp
@@ -40,6 +40,16 @@ QgsFeatureRequest::QgsFeatureRequest( QgsFeatureId fid )
 {
 }
 
+QgsFeatureRequest::QgsFeatureRequest( QgsFeatureIds fids )
+    : mFilter( FilterFids )
+    , mFilterFids( fids )
+    , mFilterExpression( nullptr )
+    , mFlags( nullptr )
+    , mLimit( -1 )
+{
+
+}
+
 QgsFeatureRequest::QgsFeatureRequest( const QgsRectangle& rect )
     : mFilter( FilterRect )
     , mFilterRect( rect )
diff --git a/src/core/qgsfeaturerequest.h b/src/core/qgsfeaturerequest.h
@@ -227,6 +227,8 @@ class CORE_EXPORT QgsFeatureRequest
     QgsFeatureRequest();
     //! construct a request with feature ID filter
     explicit QgsFeatureRequest( QgsFeatureId fid );
+    //! construct a request with feature ID filter
+    explicit QgsFeatureRequest( QgsFeatureIds fids );
     //! construct a request with rectangle filter
     explicit QgsFeatureRequest( const QgsRectangle& rect );
     //! construct a request with a filter expression
diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
@@ -1112,6 +1112,23 @@ QgsFeatureIterator QgsVectorLayer::getFeatures( const QgsFeatureRequest& request
   return QgsFeatureIterator( new QgsVectorLayerFeatureIterator( new QgsVectorLayerFeatureSource( this ), true, request ) );
 }
 
+QgsFeatureIterator QgsVectorLayer::getFeatures( const QString& expression )
+{
+  return getFeatures( QgsFeatureRequest( expression ) );
+}
+
+QgsFeature QgsVectorLayer::getFeature( QgsFeatureId fid )
+{
+  QgsFeature feature;
+  getFeatures( QgsFeatureRequest( fid ) ).nextFeature( feature );
+  return feature;
+}
+
+QgsFeatureIterator QgsVectorLayer::getFeatures( QgsFeatureIds fids )
+{
+  return getFeatures( QgsFeatureRequest( fids ) );
+}
+
 
 bool QgsVectorLayer::addFeature( QgsFeature& feature, bool alsoUpdateExtent )
 {
diff --git a/src/core/qgsvectorlayer.h b/src/core/qgsvectorlayer.h
@@ -987,6 +987,22 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
      */
     QgsFeatureIterator getFeatures( const QgsFeatureRequest& request = QgsFeatureRequest() ) const;
 
+    /**
+     * Query the provider for features matching a given expression.
+     */
+    QgsFeatureIterator getFeatures( const QString& expression );
+
+    /**
+     * Query the provider for the feature with the given id.
+     * If there is no such feature, the returned feature will be invalid.
+     */
+    QgsFeature getFeature( QgsFeatureId fid );
+
+    /**
+     * Query the provider for the features with the given ids.
+     */
+    QgsFeatureIterator getFeatures( QgsFeatureIds fids );
+
     /** Adds a feature
         @param feature feature to add
         @param alsoUpdateExtent If True, will also go to the effort of e.g. updating the extents.
