From 7e20fe4cdcc75624d16db211abccaa6cd4e17a65 Mon Sep 17 00:00:00 2001
From: "Juergen E. Fischer" <jef@norbit.de>
Date: Sat, 27 Jan 2018 17:07:33 +0100
Subject: [PATCH] make converting to multi geometries to fullfil provider
 geometry constraints the last step and use earlier conversions (fixes #17643)

---
 src/core/geometry/qgsgeometrycollection.cpp |  2 ++
 src/core/qgsvectordataprovider.cpp          | 30 ++++++++++++---------
 tests/src/python/test_provider_postgres.py  | 27 ++++++++++++++++---
 3 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/src/core/geometry/qgsgeometrycollection.cpp b/src/core/geometry/qgsgeometrycollection.cpp
index e1c0bdc7db2f..577aa9f17022 100644
--- a/src/core/geometry/qgsgeometrycollection.cpp
+++ b/src/core/geometry/qgsgeometrycollection.cpp
@@ -852,5 +852,7 @@ int QgsGeometryCollection::childCount() const
 
 QgsAbstractGeometry *QgsGeometryCollection::childGeometry( int index ) const
 {
+  if ( index < 0 || index > mGeometries.count() )
+    return nullptr;
   return mGeometries.at( index );
 }
diff --git a/src/core/qgsvectordataprovider.cpp b/src/core/qgsvectordataprovider.cpp
index 66f58bf135e7..8498bbb902bf 100644
--- a/src/core/qgsvectordataprovider.cpp
+++ b/src/core/qgsvectordataprovider.cpp
@@ -725,17 +725,6 @@ QgsGeometry QgsVectorDataProvider::convertToProviderType( const QgsGeometry &geo
     }
   }
 
-  //convert to multitype if necessary
-  if ( QgsWkbTypes::isMultiType( providerGeomType ) && !QgsWkbTypes::isMultiType( geometry->wkbType() ) )
-  {
-    outputGeom = QgsGeometryFactory::geomFromWkbType( providerGeomType );
-    QgsGeometryCollection *geomCollection = qgsgeometry_cast<QgsGeometryCollection *>( outputGeom.get() );
-    if ( geomCollection )
-    {
-      geomCollection->addGeometry( geometry->clone() );
-    }
-  }
-
   //convert to curved type if necessary
   if ( !QgsWkbTypes::isCurvedType( geometry->wkbType() ) && QgsWkbTypes::isCurvedType( providerGeomType ) )
   {
@@ -749,14 +738,27 @@ QgsGeometry QgsVectorDataProvider::convertToProviderType( const QgsGeometry &geo
   //convert to linear type from curved type
   if ( QgsWkbTypes::isCurvedType( geometry->wkbType() ) && !QgsWkbTypes::isCurvedType( providerGeomType ) )
   {
-    QgsAbstractGeometry *segmentizedGeom = nullptr;
-    segmentizedGeom = outputGeom ? outputGeom->segmentize() : geometry->segmentize();
+    QgsAbstractGeometry *segmentizedGeom = outputGeom ? outputGeom->segmentize() : geometry->segmentize();
     if ( segmentizedGeom )
     {
       outputGeom.reset( segmentizedGeom );
     }
   }
 
+  //convert to multitype if necessary
+  if ( QgsWkbTypes::isMultiType( providerGeomType ) && !QgsWkbTypes::isMultiType( geometry->wkbType() ) )
+  {
+    std::unique_ptr< QgsAbstractGeometry > collGeom( QgsGeometryFactory::geomFromWkbType( providerGeomType ) );
+    QgsGeometryCollection *geomCollection = qgsgeometry_cast<QgsGeometryCollection *>( collGeom.get() );
+    if ( geomCollection )
+    {
+      if ( geomCollection->addGeometry( outputGeom ? outputGeom->clone() : geometry->clone() ) )
+      {
+        outputGeom.reset( collGeom.release() );
+      }
+    }
+  }
+
   //set z/m types
   if ( QgsWkbTypes::hasZ( providerGeomType ) )
   {
@@ -766,6 +768,7 @@ QgsGeometry QgsVectorDataProvider::convertToProviderType( const QgsGeometry &geo
     }
     outputGeom->addZValue();
   }
+
   if ( QgsWkbTypes::hasM( providerGeomType ) )
   {
     if ( !outputGeom )
@@ -779,6 +782,7 @@ QgsGeometry QgsVectorDataProvider::convertToProviderType( const QgsGeometry &geo
   {
     return QgsGeometry( outputGeom.release() );
   }
+
   return QgsGeometry();
 }
 
diff --git a/tests/src/python/test_provider_postgres.py b/tests/src/python/test_provider_postgres.py
index 39bd0906f81e..7031ac9a556f 100644
--- a/tests/src/python/test_provider_postgres.py
+++ b/tests/src/python/test_provider_postgres.py
@@ -37,8 +37,9 @@
     QgsReadWriteContext,
     QgsRectangle,
     QgsDefaultValue,
-    QgsDataSourceUri,
-    QgsProject
+    QgsProject,
+    QgsWkbTypes,
+    QgsGeometry
 )
 from qgis.gui import QgsGui
 from qgis.PyQt.QtCore import QDate, QTime, QDateTime, QVariant, QDir, QObject
@@ -807,7 +808,7 @@ def _test(table, schema=None):
 
             table = ("%s" % table) if schema is None else ("\"%s\".\"%s\"" % (schema, table))
             dest_uri = "%s sslmode=disable table=%s  (geom) sql" % (self.dbconn, table)
-            err = QgsVectorLayerExporter.exportLayer(lyr, dest_uri, "postgres", lyr.crs())
+            QgsVectorLayerExporter.exportLayer(lyr, dest_uri, "postgres", lyr.crs())
             olyr = QgsVectorLayer(dest_uri, "y", "postgres")
             self.assertTrue(olyr.isValid(), "Failed URI: %s" % dest_uri)
 
@@ -1035,6 +1036,26 @@ def testStyleDatabaseWithService(self):
         ids = styles[1]
         self.assertEqual(len(ids), 0)
 
+    def testCurveToMultipolygon(self):
+        self.execSQLCommand('CREATE TABLE IF NOT EXISTS multicurve(pk SERIAL NOT NULL PRIMARY KEY, geom public.geometry(MultiPolygon, 4326))')
+        self.execSQLCommand('TRUNCATE multicurve')
+
+        vl = QgsVectorLayer(self.dbconn + ' sslmode=disable key=\'pk\' srid=4326 type=MULTIPOLYGON table="multicurve" (geom) sql=', 'test', 'postgres')
+
+        f = QgsFeature(vl.fields())
+        f.setGeometry(QgsGeometry.fromWkt('CurvePolygon(CircularString (20 30, 50 30, 50 90, 10 50, 20 30))'))
+        self.assertTrue(vl.startEditing())
+        self.assertTrue(vl.addFeatures([f]))
+        self.assertTrue(vl.commitChanges())
+
+        f = next(vl.getFeatures(QgsFeatureRequest()))
+
+        g = f.geometry().constGet()
+        self.assertTrue(g)
+        self.assertEqual(g.wkbType(), QgsWkbTypes.MultiPolygon)
+        self.assertEqual(g.childCount(), 1)
+        self.assertTrue(g.childGeometry(0).vertexCount() > 3)
+
 
 class TestPyQgsPostgresProviderCompoundKey(unittest.TestCase, ProviderTestCase):