[memory] Fix memory provider does not return correct min/max

values after adding or editing features

The cache was not cleared correctly in this case

Fix sponsored by LINZ

(cherry-picked from 6b74268)

Author: nyalldawson

src/core/providers/memory/qgsmemoryprovider.cpp

@@ -402,6 +402,7 @@ bool QgsMemoryProvider::addFeatures( QgsFeatureList &flist, Flags )
     mNextFeatureId++;
   }
 
+  clearMinMaxCache();
   return result;
 }
 
@@ -423,6 +424,7 @@ bool QgsMemoryProvider::deleteFeatures( const QgsFeatureIds &id )
   }
 
   updateExtents();
+  clearMinMaxCache();
 
   return true;
 }
@@ -504,6 +506,7 @@ bool QgsMemoryProvider::deleteAttributes( const QgsAttributeIds &attributes )
       f.setAttributes( attr );
     }
   }
+  clearMinMaxCache();
   return true;
 }
 
@@ -519,6 +522,7 @@ bool QgsMemoryProvider::changeAttributeValues( const QgsChangedAttributesMap &at
     for ( QgsAttributeMap::const_iterator it2 = attrs.constBegin(); it2 != attrs.constEnd(); ++it2 )
       fit->setAttribute( it2.key(), it2.value() );
   }
+  clearMinMaxCache();
   return true;
 }
 

src/core/qgsvectordataprovider.cpp

@@ -471,6 +471,8 @@ QVariant QgsVectorDataProvider::aggregate( QgsAggregateCalculator::Aggregate agg
 void QgsVectorDataProvider::clearMinMaxCache()
 {
   mCacheMinMaxDirty = true;
+  mCacheMinValues.clear();
+  mCacheMaxValues.clear();
 }
 
 void QgsVectorDataProvider::fillMinMaxCache() const

tests/src/python/test_provider_memory.py

@@ -444,6 +444,71 @@ def testThreadSafetyWithIndex(self):
         request = QgsFeatureRequest().setFilterRect(extent)
         self.assertTrue(QgsTestUtils.testProviderIteratorThreadSafety(self.source, request))
 
+    def testMinMaxCache(self):
+        """
+        Test that min/max cache is appropriately cleared
+        :return:
+        """
+        vl = QgsVectorLayer(
+            'Point?crs=epsg:4326&field=f1:integer&field=f2:integer',
+            'test', 'memory')
+        self.assertTrue(vl.isValid())
+
+        f1 = QgsFeature()
+        f1.setAttributes([5, -200])
+        f2 = QgsFeature()
+        f2.setAttributes([3, 300])
+        f3 = QgsFeature()
+        f3.setAttributes([1, 100])
+        f4 = QgsFeature()
+        f4.setAttributes([2, 200])
+        f5 = QgsFeature()
+        f5.setAttributes([4, 400])
+        res, [f1, f2, f3, f4, f5] = vl.dataProvider().addFeatures([f1, f2, f3, f4, f5])
+        self.assertTrue(res)
+
+        self.assertEqual(vl.dataProvider().minimumValue(0), 1)
+        self.assertEqual(vl.dataProvider().minimumValue(1), -200)
+        self.assertEqual(vl.dataProvider().maximumValue(0), 5)
+        self.assertEqual(vl.dataProvider().maximumValue(1), 400)
+
+        # add feature
+        f6 = QgsFeature()
+        f6.setAttributes([15, 1400])
+        res, [f6] = vl.dataProvider().addFeatures([f6])
+        self.assertTrue(res)
+        self.assertEqual(vl.dataProvider().minimumValue(0), 1)
+        self.assertEqual(vl.dataProvider().minimumValue(1), -200)
+        self.assertEqual(vl.dataProvider().maximumValue(0), 15)
+        self.assertEqual(vl.dataProvider().maximumValue(1), 1400)
+        f7 = QgsFeature()
+        f7.setAttributes([-1, -1400])
+        res, [f7] = vl.dataProvider().addFeatures([f7])
+        self.assertTrue(res)
+        self.assertEqual(vl.dataProvider().minimumValue(0), -1)
+        self.assertEqual(vl.dataProvider().minimumValue(1), -1400)
+        self.assertEqual(vl.dataProvider().maximumValue(0), 15)
+        self.assertEqual(vl.dataProvider().maximumValue(1), 1400)
+
+        # change attribute values
+        self.assertTrue(vl.dataProvider().changeAttributeValues({f6.id(): {0: 3, 1: 150}, f7.id(): {0: 4, 1: -100}}))
+        self.assertEqual(vl.dataProvider().minimumValue(0), 1)
+        self.assertEqual(vl.dataProvider().minimumValue(1), -200)
+        self.assertEqual(vl.dataProvider().maximumValue(0), 5)
+        self.assertEqual(vl.dataProvider().maximumValue(1), 400)
+
+        # delete features
+        self.assertTrue(vl.dataProvider().deleteFeatures([f4.id(), f1.id()]))
+        self.assertEqual(vl.dataProvider().minimumValue(0), 1)
+        self.assertEqual(vl.dataProvider().minimumValue(1), -100)
+        self.assertEqual(vl.dataProvider().maximumValue(0), 4)
+        self.assertEqual(vl.dataProvider().maximumValue(1), 400)
+
+        # delete attributes
+        self.assertTrue(vl.dataProvider().deleteAttributes([0]))
+        self.assertEqual(vl.dataProvider().minimumValue(0), -100)
+        self.assertEqual(vl.dataProvider().maximumValue(0), 400)
+
 
 class TestPyQgsMemoryProviderIndexed(unittest.TestCase, ProviderTestCase):