Add method for exporting QgsFeatureList to GeoJSON featurecollection

python/core/qgsjsonutils.sip

@@ -114,11 +114,20 @@ class QgsJSONExporter
      * @param id optional ID to use as GeoJSON feature's ID instead of input feature's ID. If omitted, feature's
      * ID is used.
      * @returns GeoJSON string
+     * @see exportFeatures()
      */
     QString exportFeature( const QgsFeature& feature,
                            const QVariantMap& extraProperties = QVariantMap(),
                            const QVariant& id = QVariant() ) const;
 
+
+    /** Returns a GeoJSON string representation of a list of features (feature collection).
+     * @param features features to convert
+     * @returns GeoJSON string
+     * @see exportFeature()
+     */
+    QString exportFeatures( const QgsFeatureList& features ) const;
+
 };
 
 

src/core/qgsjsonutils.cpp

@@ -165,6 +165,17 @@ QString QgsJSONExporter::exportFeature( const QgsFeature& feature, const QVarian
   return s;
 }
 
+QString QgsJSONExporter::exportFeatures( const QgsFeatureList& features ) const
+{
+  QStringList featureJSON;
+  Q_FOREACH ( const QgsFeature& feature, features )
+  {
+    featureJSON << exportFeature( feature );
+  }
+
+  return QString( "{ \"type\": \"FeatureCollection\",\n    \"features\":[\n%1\n]}" ).arg( featureJSON.join( ",\n" ) );
+}
+
 
 
 //

src/core/qgsjsonutils.h

@@ -134,12 +134,21 @@ class CORE_EXPORT QgsJSONExporter
      * @param id optional ID to use as GeoJSON feature's ID instead of input feature's ID. If omitted, feature's
      * ID is used.
      * @returns GeoJSON string
+     * @see exportFeatures()
      */
     QString exportFeature( const QgsFeature& feature,
                            const QVariantMap& extraProperties = QVariantMap(),
                            const QVariant& id = QVariant() ) const;
 
 
+    /** Returns a GeoJSON string representation of a list of features (feature collection).
+     * @param features features to convert
+     * @returns GeoJSON string
+     * @see exportFeature()
+     */
+    QString exportFeatures( const QgsFeatureList& features ) const;
+
+
   private:
 
     //! Maximum number of decimal places for geometry coordinates

tests/src/python/test_qgsjsonutils.py

@@ -466,6 +466,69 @@ class TestQgsJSONUtils(unittest.TestCase):
 }"""
         self.assertEqual(exporter.exportFeature(pf2), expected)
 
+    def testExportFeatures(self):
+        """ Test exporting feature collections """
+
+        fields = QgsFields()
+        fields.append(QgsField("name", QVariant.String))
+        fields.append(QgsField("cost", QVariant.Double))
+        fields.append(QgsField("population", QVariant.Int))
+
+        feature = QgsFeature(fields, 5)
+        feature.setGeometry(QgsGeometry(QgsPointV2(5, 6)))
+        feature.setAttributes(['Valsier Peninsula', 6.8, 198])
+
+        exporter = QgsJSONExporter()
+
+        # single feature
+        expected = """{ "type": "FeatureCollection",
+    "features":[
+{
+   "type":"Feature",
+   "id":5,
+   "geometry":
+   {"type": "Point", "coordinates": [5, 6]},
+   "properties":{
+      "name":"Valsier Peninsula",
+      "cost":6.8,
+      "population":198
+   }
+}
+]}"""
+        self.assertEqual(exporter.exportFeatures([feature]), expected)
+
+        # multiple features
+        feature2 = QgsFeature(fields, 6)
+        feature2.setGeometry(QgsGeometry(QgsPointV2(7, 8)))
+        feature2.setAttributes(['Henry Gale Island', 9.7, 38])
+
+        expected = """{ "type": "FeatureCollection",
+    "features":[
+{
+   "type":"Feature",
+   "id":5,
+   "geometry":
+   {"type": "Point", "coordinates": [5, 6]},
+   "properties":{
+      "name":"Valsier Peninsula",
+      "cost":6.8,
+      "population":198
+   }
+},
+{
+   "type":"Feature",
+   "id":6,
+   "geometry":
+   {"type": "Point", "coordinates": [7, 8]},
+   "properties":{
+      "name":"Henry Gale Island",
+      "cost":9.7,
+      "population":38
+   }
+}
+]}"""
+        self.assertEqual(exporter.exportFeatures([feature, feature2]), expected)
+
 
 if __name__ == "__main__":
     unittest.main()