[api] Raises ValueError and TypeError exceptions when QgsGeometry.asP…

…olygon() is called on non-single-polygon geometries Previously we would just return an empty list when geometries of invalid type were used, but this is dangerous and we are safer to explicitly raise errors preventing use of asPolygon() with incompatible geometry types. (cherry picked from commit 514c5e2)
qgis · Dec 20, 2018 · 7ef9760 · 7ef9760
1 parent 01f6ced
commit 7ef9760
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Showing 3 changed files with 90 additions and 5 deletions.
diff --git a/python/core/auto_generated/geometry/qgsgeometry.sip.in b/python/core/auto_generated/geometry/qgsgeometry.sip.in
@@ -1473,10 +1473,35 @@ will be raised.
     }
 %End
 
-    QgsPolygonXY asPolygon() const;
+
+    SIP_PYOBJECT asPolygon() const /TypeHint="QgsPolygonXY"/;
 %Docstring
-Returns contents of the geometry as a polygon
-if wkbType is WKBPolygon, otherwise an empty list
+Returns the contents of the geometry as a polygon.
+
+Any z or m values present in the geometry will be discarded. If the geometry is a curved polygon type
+(such as a CurvePolygon), it will be automatically segmentized.
+
+This method works only with single-polygon (or single-curve polygon) geometry types. If the geometry
+is not a single-polygon type, a TypeError will be raised. If the geometry is null, a ValueError
+will be raised.
+%End
+%MethodCode
+    const QgsWkbTypes::Type type = sipCpp->wkbType();
+    if ( sipCpp->isNull() )
+    {
+      PyErr_SetString( PyExc_ValueError, QStringLiteral( "Null geometry cannot be converted to a polygon." ).toUtf8().constData() );
+      sipIsErr = 1;
+    }
+    else if ( QgsWkbTypes::geometryType( type ) != QgsWkbTypes::PolygonGeometry || QgsWkbTypes::isMultiType( type ) )
+    {
+      PyErr_SetString( PyExc_TypeError, QStringLiteral( "%1 geometry cannot be converted to a polygon. Only single polygon or curve polygon types are permitted." ).arg( QgsWkbTypes::displayString( type ) ).toUtf8().constData() );
+      sipIsErr = 1;
+    }
+    else
+    {
+      const sipMappedType *qvector_type = sipFindMappedType( "QVector<QVector<QgsPointXY>>" );
+      sipRes = sipConvertFromNewType( new QgsPolygonXY( sipCpp->asPolygon() ), qvector_type, Py_None );
+    }
 %End
 
     QgsMultiPointXY asMultiPoint() const;

diff --git a/src/core/geometry/qgsgeometry.h b/src/core/geometry/qgsgeometry.h
@@ -1498,11 +1498,49 @@ class CORE_EXPORT QgsGeometry
     % End
 #endif
 
+#ifndef SIP_RUN
+
     /**
-     * Returns contents of the geometry as a polygon
-     * if wkbType is WKBPolygon, otherwise an empty list
+     * Returns the contents of the geometry as a polygon.
+     *
+     * Any z or m values present in the geometry will be discarded. If the geometry is a curved polygon type
+     * (such as a CurvePolygon), it will be automatically segmentized.
+     *
+     * \warning If the geometry is not a single-polygon (or single-curve polygon) type, an empty list will be returned.
      */
     QgsPolygonXY asPolygon() const;
+#else
+
+    /**
+     * Returns the contents of the geometry as a polygon.
+     *
+     * Any z or m values present in the geometry will be discarded. If the geometry is a curved polygon type
+     * (such as a CurvePolygon), it will be automatically segmentized.
+     *
+     * This method works only with single-polygon (or single-curve polygon) geometry types. If the geometry
+     * is not a single-polygon type, a TypeError will be raised. If the geometry is null, a ValueError
+     * will be raised.
+     */
+    SIP_PYOBJECT asPolygon() const SIP_TYPEHINT( QgsPolygonXY );
+    % MethodCode
+    const QgsWkbTypes::Type type = sipCpp->wkbType();
+    if ( sipCpp->isNull() )
+    {
+      PyErr_SetString( PyExc_ValueError, QStringLiteral( "Null geometry cannot be converted to a polygon." ).toUtf8().constData() );
+      sipIsErr = 1;
+    }
+    else if ( QgsWkbTypes::geometryType( type ) != QgsWkbTypes::PolygonGeometry || QgsWkbTypes::isMultiType( type ) )
+    {
+      PyErr_SetString( PyExc_TypeError, QStringLiteral( "%1 geometry cannot be converted to a polygon. Only single polygon or curve polygon types are permitted." ).arg( QgsWkbTypes::displayString( type ) ).toUtf8().constData() );
+      sipIsErr = 1;
+    }
+    else
+    {
+      const sipMappedType *qvector_type = sipFindMappedType( "QVector<QVector<QgsPointXY>>" );
+      sipRes = sipConvertFromNewType( new QgsPolygonXY( sipCpp->asPolygon() ), qvector_type, Py_None );
+    }
+    % End
+#endif
 
     /**
      * Returns contents of the geometry as a multi point

diff --git a/tests/src/python/test_qgsgeometry.py b/tests/src/python/test_qgsgeometry.py
@@ -288,6 +288,28 @@ def testPointXY(self):
         with self.assertRaises(ValueError):
             QgsGeometry().asPolyline()
 
+        # as polygon
+        self.assertEqual(QgsGeometry.fromWkt('Polygon((11 13,14 15, 11 15, 11 13))').asPolygon(),
+                         [[QgsPointXY(11, 13), QgsPointXY(14, 15), QgsPointXY(11, 15), QgsPointXY(11, 13)]])
+        self.assertEqual(QgsGeometry.fromWkt('PolygonZ((11 13 1,14 15 2, 11 15 3, 11 13 1))').asPolygon(),
+                         [[QgsPointXY(11, 13), QgsPointXY(14, 15), QgsPointXY(11, 15), QgsPointXY(11, 13)]])
+        self.assertEqual(QgsGeometry.fromWkt('PolygonM((11 13 1,14 15 2, 11 15 3, 11 13 1))').asPolygon(),
+                         [[QgsPointXY(11, 13), QgsPointXY(14, 15), QgsPointXY(11, 15), QgsPointXY(11, 13)]])
+        self.assertEqual(QgsGeometry.fromWkt('PolygonZM((11 13 1 11,14 15 2 12 , 11 15 3 13 , 11 13 1 11))').asPolygon(),
+                         [[QgsPointXY(11, 13), QgsPointXY(14, 15), QgsPointXY(11, 15), QgsPointXY(11, 13)]])
+        with self.assertRaises(TypeError):
+            QgsGeometry.fromWkt('Point(11 13)').asPolygon()
+        with self.assertRaises(TypeError):
+            QgsGeometry.fromWkt('MultiPoint(11 13,14 15)').asPolygon()
+        with self.assertRaises(TypeError):
+            QgsGeometry.fromWkt('MultiLineString((11 13, 14 15),(1 2, 3 4))').asPolygon()
+        with self.assertRaises(TypeError):
+            QgsGeometry.fromWkt('LineString(11 13,14 15)').asPolygon()
+        with self.assertRaises(TypeError):
+            QgsGeometry.fromWkt('MultiPolygon(((11 13,14 15, 11 15, 11 13)))').asPolygon()
+        with self.assertRaises(ValueError):
+            QgsGeometry().asPolygon()
+
     def testReferenceGeometry(self):
         """ Test parsing a whole range of valid reference wkt formats and variants, and checking
         expected values such as length, area, centroids, bounding boxes, etc of the resultant geometry.