[mssql] Fix empty extent handling

Author: nyalldawson

src/providers/mssql/qgsmssqlprovider.cpp

@@ -1027,10 +1027,20 @@ void QgsMssqlProvider::UpdateStatistics( bool estimate ) const
 
   if ( !readAllGeography && query.next() )
   {
-    mExtent.setXMinimum( query.value( 0 ).toDouble() );
-    mExtent.setYMinimum( query.value( 1 ).toDouble() );
-    mExtent.setXMaximum( query.value( 2 ).toDouble() );
-    mExtent.setYMaximum( query.value( 3 ).toDouble() );
+    if ( QgsVariantUtils::isNull( query.value( 0 ) )
+         || QgsVariantUtils::isNull( query.value( 1 ) )
+         || QgsVariantUtils::isNull( query.value( 2 ) )
+         || QgsVariantUtils::isNull( query.value( 3 ) ) )
+    {
+      mExtent.setNull();
+    }
+    else
+    {
+      mExtent.setXMinimum( query.value( 0 ).toDouble() );
+      mExtent.setYMinimum( query.value( 1 ).toDouble() );
+      mExtent.setXMaximum( query.value( 2 ).toDouble() );
+      mExtent.setYMaximum( query.value( 3 ).toDouble() );
+    }
     return;
   }
 
@@ -1042,15 +1052,7 @@ void QgsMssqlProvider::UpdateStatistics( bool estimate ) const
     if ( geom )
     {
       const QgsRectangle rect = geom->boundingBox();
-
-      if ( rect.xMinimum() < mExtent.xMinimum() )
-        mExtent.setXMinimum( rect.xMinimum() );
-      if ( rect.yMinimum() < mExtent.yMinimum() )
-        mExtent.setYMinimum( rect.yMinimum() );
-      if ( rect.xMaximum() > mExtent.xMaximum() )
-        mExtent.setXMaximum( rect.xMaximum() );
-      if ( rect.yMaximum() > mExtent.yMaximum() )
-        mExtent.setYMaximum( rect.yMaximum() );
+      mExtent.combineExtentWith( rect );
 
       mWkbType = geom->wkbType();
       mSRId = mParser.GetSRSId();
@@ -1061,7 +1063,7 @@ void QgsMssqlProvider::UpdateStatistics( bool estimate ) const
 // Return the extent of the layer
 QgsRectangle QgsMssqlProvider::extent() const
 {
-  if ( mExtent.isEmpty() )
+  if ( mExtent.isNull() )
     UpdateStatistics( mUseEstimatedMetadata );
   return mExtent;
 }

tests/src/python/providertestbase.py

@@ -558,10 +558,18 @@ def testMaxValue(self):
     def testExtent(self):
         reference_extent = self.referenceExtent()
         provider_extent = self.source.extent()
-        self.assertAlmostEqual(provider_extent.xMinimum(), reference_extent.xMinimum())
-        self.assertAlmostEqual(provider_extent.xMaximum(), reference_extent.xMaximum())
-        self.assertAlmostEqual(provider_extent.yMinimum(), reference_extent.yMinimum())
-        self.assertAlmostEqual(provider_extent.yMaximum(), reference_extent.yMaximum())
+        self.assertAlmostEqual(
+            provider_extent.xMinimum(), reference_extent.xMinimum(), 5
+        )
+        self.assertAlmostEqual(
+            provider_extent.xMaximum(), reference_extent.xMaximum(), 5
+        )
+        self.assertAlmostEqual(
+            provider_extent.yMinimum(), reference_extent.yMinimum(), 5
+        )
+        self.assertAlmostEqual(
+            provider_extent.yMaximum(), reference_extent.yMaximum(), 5
+        )
 
     def testExtentSubsetString(self):
         if self.source.supportsSubsetString():

tests/src/python/test_provider_mssql.py

@@ -746,9 +746,7 @@ def testInvalidGeometries(self):
         )
         self.assertTrue(vl.isValid())
 
-        self.assertEqual(
-            vl.dataProvider().extent().toString(1), "Empty"
-        )  # HAHA - you asked for it
+        self.assertTrue(vl.dataProvider().extent().isNull())  # HAHA - you asked for it
         # burn through features - don't expect anything wrong here yet
         count = 0
         for f in vl.dataProvider().getFeatures():
@@ -772,7 +770,7 @@ def testInvalidGeometries(self):
             "mssql",
         )
         self.assertTrue(vl.isValid())
-        self.assertEqual(vl.dataProvider().extent().toString(1), "Empty")
+        self.assertTrue(vl.dataProvider().extent().isNull())
 
     def testEvaluateDefaultValueClause(self):