check uniqueCheck before overwrite defaultValueClause

and some tests for it
this fixes #20397 and fixes #20431

(cherry-picked from 32b7d7e)

Author: signedav

src/core/qgsvectorlayerutils.cpp

@@ -413,7 +413,7 @@ QgsFeature QgsVectorLayerUtils::createFeature( const QgsVectorLayer *layer, cons
 
     // 4. provider side default literal
     // note - deliberately not using else if!
-    if ( ( !v.isValid() || ( fields.at( idx ).constraints().constraints() & QgsFieldConstraints::ConstraintUnique  && QgsVectorLayerUtils::valueExists( layer, idx, v ) ) )
+    if ( ( !v.isValid() || ( checkUnique && fields.at( idx ).constraints().constraints() & QgsFieldConstraints::ConstraintUnique  && QgsVectorLayerUtils::valueExists( layer, idx, v ) ) )
          && fields.fieldOrigin( idx ) == QgsFields::OriginProvider )
     {
       int providerIndex = fields.fieldOriginIndex( idx );

tests/src/python/test_qgsvectorlayerutils.py

@@ -12,6 +12,7 @@
 # This will get replaced with a git SHA1 when you do a git archive
 __revision__ = '$Format:%H$'
 
+import os
 import qgis  # NOQA
 
 from qgis.PyQt.QtCore import QVariant
@@ -297,6 +298,43 @@ def testCreateFeature(self):
         f = QgsVectorLayerUtils.createFeature(layer, attributes={0: 'test_1', 1: 132})
         self.assertEqual(f.attributes(), ['test_5', 132, NULL])
 
+        """ test creating a feature respecting unique values of postgres provider """
+        layer = QgsVectorLayer("Point?field=fldtxt:string&field=fldint:integer&field=flddbl:double",
+                               "addfeat", "memory")
+
+        # init connection string
+        dbconn = 'dbname=\'qgis_test\''
+        if 'QGIS_PGTEST_DB' in os.environ:
+            dbconn = os.environ['QGIS_PGTEST_DB']
+
+        # create a vector layer
+        pg_layer = QgsVectorLayer('{} table="qgis_test"."authors" sql='.format(dbconn), "authors", "postgres")
+        self.assertTrue(pg_layer.isValid())
+        # check the default clause
+        default_clause = 'nextval(\'qgis_test.authors_pk_seq\'::regclass)'
+        self.assertEqual(pg_layer.dataProvider().defaultValueClause(0), default_clause)
+
+        # though default_clause is after the first create not unique (until save), it should fill up all the features with it
+        pg_layer.startEditing()
+        f = QgsVectorLayerUtils.createFeature(pg_layer)
+        self.assertEqual(f.attributes(), [default_clause, NULL])
+        self.assertTrue(pg_layer.addFeatures([f]))
+        self.assertTrue(QgsVectorLayerUtils.valueExists(pg_layer, 0, default_clause))
+        f = QgsVectorLayerUtils.createFeature(pg_layer)
+        self.assertEqual(f.attributes(), [default_clause, NULL])
+        self.assertTrue(pg_layer.addFeatures([f]))
+        f = QgsVectorLayerUtils.createFeature(pg_layer)
+        self.assertEqual(f.attributes(), [default_clause, NULL])
+        self.assertTrue(pg_layer.addFeatures([f]))
+        # if a unique value is passed, use it
+        f = QgsVectorLayerUtils.createFeature(pg_layer, attributes={0: 40, 1: NULL})
+        self.assertEqual(f.attributes(), [40, NULL])
+        # and if a default value is configured use it as well
+        pg_layer.setDefaultValueDefinition(0, QgsDefaultValue('11*4'))
+        f = QgsVectorLayerUtils.createFeature(pg_layer)
+        self.assertEqual(f.attributes(), [44, NULL])
+        pg_layer.rollBack()
+
     def testDuplicateFeature(self):
         """ test duplicating a feature """