From a6bd16583fdb6aa3a5ec7c78bc2cdb4305f11b02 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Thu, 25 Jan 2024 17:29:44 +0100
Subject: [PATCH] QgsVectorLayerUtils::guessFriendlyIdentifierField(): improve
 heuristics to work better with WFS layers analyzed with the GMLAS driver

---
 src/core/vector/qgsvectorlayerutils.cpp      | 30 +++++++++++++++++++-
 tests/src/python/test_qgsvectorlayerutils.py | 13 +++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/core/vector/qgsvectorlayerutils.cpp b/src/core/vector/qgsvectorlayerutils.cpp
index fc5468155a64..42d423d0c523 100644
--- a/src/core/vector/qgsvectorlayerutils.cpp
+++ b/src/core/vector/qgsvectorlayerutils.cpp
@@ -1239,9 +1239,37 @@ QString QgsVectorLayerUtils::guessFriendlyIdentifierField( const QgsFields &fiel
       break;
   }
 
-  const QString candidateName = bestCandidateName.isEmpty() ? bestCandidateNameWithAntiCandidate : bestCandidateName;
+  QString candidateName = bestCandidateName.isEmpty() ? bestCandidateNameWithAntiCandidate : bestCandidateName;
   if ( !candidateName.isEmpty() )
   {
+    // Special case for layers got from WFS using the OGR GMLAS field parsing logic.
+    // Such layers contain a "id" field (the gml:id attribute of the object),
+    // as well as a gml_name (a <gml:name>) element. However this gml:name is often
+    // absent, partly because it is a property of the base class in GML schemas, and
+    // that a lot of readers are not able to deduce its potential presence.
+    // So try to look at another field whose name would end with _name
+    // And fallback to using the "id" field that should always be filled.
+    if ( candidateName == QLatin1String( "gml_name" ) &&
+         fields.indexOf( QStringLiteral( "id" ) ) >= 0 )
+    {
+      candidateName.clear();
+      // Try to find a field ending with "_name", which is not "gml_name"
+      for ( const QgsField &field : fields )
+      {
+        const QString fldName = field.name();
+        if ( fldName != QLatin1String( "gml_name" ) && fldName.endsWith( QLatin1String( "_name" ) ) )
+        {
+          candidateName = fldName;
+          break;
+        }
+      }
+      if ( candidateName.isEmpty() )
+      {
+        // Fallback to "id"
+        candidateName = QStringLiteral( "id" );
+      }
+    }
+
     if ( foundFriendly )
       *foundFriendly = true;
     return candidateName;
diff --git a/tests/src/python/test_qgsvectorlayerutils.py b/tests/src/python/test_qgsvectorlayerutils.py
index f1d01e98490b..b467c828dbd2 100644
--- a/tests/src/python/test_qgsvectorlayerutils.py
+++ b/tests/src/python/test_qgsvectorlayerutils.py
@@ -880,6 +880,19 @@ def testGuessFriendlyIdentifierField(self):
         fields.append(QgsField('org', QVariant.String))
         self.assertEqual(QgsVectorLayerUtils.guessFriendlyIdentifierField(fields), 'station')
 
+        # Particular case for WFS layers analyzed with the GMLAS driver.
+        # We prioritize a field ending with _name, but which is not gml_name
+        fields = QgsFields()
+        fields.append(QgsField('id', QVariant.String))
+        fields.append(QgsField('gml_name', QVariant.String))
+        fields.append(QgsField('other_name', QVariant.String))
+        self.assertEqual(QgsVectorLayerUtils.guessFriendlyIdentifierField(fields), 'other_name')
+
+        fields = QgsFields()
+        fields.append(QgsField('id', QVariant.String))
+        fields.append(QgsField('gml_name', QVariant.String))
+        self.assertEqual(QgsVectorLayerUtils.guessFriendlyIdentifierField(fields), 'id')
+
 
 if __name__ == '__main__':
     unittest.main()