Fix exporting geometry collections to WKT

Child types were incorrectly being dropped when the collection
consisted of mixed geometry types (eg line & polygon) (refs #13608)

python/core/geometry/qgsgeometrycollectionv2.sip

@@ -73,4 +73,12 @@ class QgsGeometryCollectionV2: public QgsAbstractGeometryV2
 
     virtual bool addZValue( double zValue = 0 );
     virtual bool addMValue( double mValue = 0 );
+
+  protected:
+
+    /** Returns whether child type names are omitted from Wkt representations of the collection
+     * @note added in QGIS 2.12
+     */
+    virtual bool wktOmitChildType() const;
+
 };

python/core/geometry/qgsmultilinestringv2.sip

@@ -17,4 +17,8 @@ class QgsMultiLineStringV2: public QgsMultiCurveV2
 
     /** Adds a geometry and takes ownership. Returns true in case of success*/
     virtual bool addGeometry( QgsAbstractGeometryV2* g );
+
+  protected:
+
+    virtual bool wktOmitChildType() const;
 };

python/core/geometry/qgsmultipointv2.sip

@@ -19,4 +19,8 @@ public:
 
   /** Adds a geometry and takes ownership. Returns true in case of success*/
   virtual bool addGeometry( QgsAbstractGeometryV2* g );
+
+  protected:
+
+    virtual bool wktOmitChildType() const;
 };

python/core/geometry/qgsmultipolygonv2.sip

@@ -19,4 +19,8 @@ class QgsMultiPolygonV2: public QgsMultiSurfaceV2
 
     /** Adds a geometry and takes ownership. Returns true in case of success*/
     virtual bool addGeometry( QgsAbstractGeometryV2* g );
+
+  protected:
+
+    virtual bool wktOmitChildType() const;
 };

src/core/geometry/qgsgeometrycollectionv2.cpp

@@ -259,11 +259,8 @@ QString QgsGeometryCollectionV2::asWkt( int precision ) const
   Q_FOREACH ( const QgsAbstractGeometryV2 *geom, mGeometries )
   {
     QString childWkt = geom->asWkt( precision );
-    if ( dynamic_cast<const QgsPointV2*>( geom ) ||
-         dynamic_cast<const QgsLineStringV2*>( geom ) ||
-         dynamic_cast<const QgsPolygonV2*>( geom ) )
+    if ( wktOmitChildType() )
     {
-      // Type names of linear geometries are omitted
       childWkt = childWkt.mid( childWkt.indexOf( "(" ) );
     }
     wkt += childWkt + ",";

src/core/geometry/qgsgeometrycollectionv2.h

@@ -125,6 +125,11 @@ class CORE_EXPORT QgsGeometryCollectionV2: public QgsAbstractGeometryV2
   protected:
     QVector< QgsAbstractGeometryV2* > mGeometries;
 
+    /** Returns whether child type names are omitted from Wkt representations of the collection
+     * @note added in QGIS 2.12
+     */
+    virtual bool wktOmitChildType() const { return false; }
+
     /** Reads a collection from a WKT string.
      */
     bool fromCollectionWkt( const QString &wkt, const QList<QgsAbstractGeometryV2*>& subtypes, const QString& defaultChildWkbType = QString() );

src/core/geometry/qgsmultilinestringv2.h

@@ -42,6 +42,10 @@ class CORE_EXPORT QgsMultiLineStringV2: public QgsMultiCurveV2
 
     /** Adds a geometry and takes ownership. Returns true in case of success*/
     virtual bool addGeometry( QgsAbstractGeometryV2* g ) override;
+
+  protected:
+
+    virtual bool wktOmitChildType() const override { return true; }
 };
 
 #endif // QGSMULTILINESTRINGV2_H

src/core/geometry/qgsmultipointv2.h

@@ -42,6 +42,11 @@ class CORE_EXPORT QgsMultiPointV2: public QgsGeometryCollectionV2
 
     /** Adds a geometry and takes ownership. Returns true in case of success*/
     virtual bool addGeometry( QgsAbstractGeometryV2* g ) override;
+
+  protected:
+
+    virtual bool wktOmitChildType() const override { return true; }
+
 };
 
 #endif // QGSMULTIPOINTV2_H

src/core/geometry/qgsmultipolygonv2.h

@@ -42,6 +42,10 @@ class CORE_EXPORT QgsMultiPolygonV2: public QgsMultiSurfaceV2
 
     /** Adds a geometry and takes ownership. Returns true in case of success*/
     virtual bool addGeometry( QgsAbstractGeometryV2* g ) override;
+
+  protected:
+
+    virtual bool wktOmitChildType() const override { return true; }
 };
 
 #endif // QGSMULTIPOLYGONV2_H

tests/src/python/test_qgsgeometry.py

@@ -94,6 +94,36 @@ class TestQgsGeometry(TestCase):
                      (QGis.WKBMultiPolygon, myMultiPolygon.type()))
         assert myMultiPolygon.wkbType() == QGis.WKBMultiPolygon, myMessage
 
+    def testExportToWkt(self):
+
+        # test exporting collections to wkt. MultiPolygon, MultiLineString and MultiPoint should omit child types
+        wkt = "MultiPolygon (((0 0, 1 0, 1 1, 2 1, 2 2, 0 2, 0 0)),((4 0, 5 0, 5 2, 3 2, 3 1, 4 1, 4 0)))"
+        g = QgsGeometry.fromWkt(wkt)
+        res = g.exportToWkt()
+        assert compareWkt(res, wkt), "Expected:\n%s\nGot:\n%s\n" % (wkt, res)
+
+        wkt = "MultiLineString ((0 0, 1 0, 1 1, 2 1, 2 0), (3 1, 5 1, 5 0, 6 0))"
+        g = QgsGeometry.fromWkt(wkt)
+        res = g.exportToWkt()
+        assert compareWkt(res, wkt), "Expected:\n%s\nGot:\n%s\n" % (wkt, res)
+
+        wkt = "MultiPoint ((10 30),(40 20),(30 10),(20 10))"
+        g = QgsGeometry.fromWkt(wkt)
+        res = g.exportToWkt()
+        assert compareWkt(res, wkt), "Expected:\n%s\nGot:\n%s\n" % (wkt, res)
+
+        #mixed GeometryCollection should keep child types
+        wkt = "GeometryCollection (Point (10 10),Point (30 30),LineString (15 15, 20 20))"
+        g = QgsGeometry.fromWkt(wkt)
+        res = g.exportToWkt()
+        assert compareWkt(res, wkt), "Expected:\n%s\nGot:\n%s\n" % (wkt, res)
+
+        #Multicurve should keep child type
+        wkt = "MultiCurve (CircularString (90 232, 95 230, 100 232),CircularString (90 232, 95 234, 100 232))"
+        g = QgsGeometry.fromWkt(wkt)
+        res = g.exportToWkt()
+        assert compareWkt(res, wkt), "Expected:\n%s\nGot:\n%s\n" % (wkt, res)
+
     def testIntersection(self):
         myLine = QgsGeometry.fromPolyline([
             QgsPoint(0, 0),