Server atlas print fix pk-less layers

src/server/services/wms/qgswmsrenderer.cpp

@@ -362,18 +362,22 @@ namespace QgsWms
       else
       {
         const QgsAttributeList pkIndexes = cLayer->primaryKeyAttributes();
-        if ( pkIndexes.size() < 1 )
+        if ( pkIndexes.size() == 0 )
         {
-          throw QgsException( QStringLiteral( "An error occurred during the Atlas print" ) );
+          QgsDebugMsgLevel( QStringLiteral( "Atlas print: layer %1 has no primary key attributes" ).arg( cLayer->name() ), 2 );
         }
+
+        // Handles the pk-less case
+        const int pkIndexesSize {std::max( pkIndexes.size(), 1 )};
+
         QStringList pkAttributeNames;
-        for ( int pkIndex : pkIndexes )
+        for ( int pkIndex : std::as_const( pkIndexes ) )
         {
           pkAttributeNames.append( cLayer->fields().at( pkIndex ).name() );
         }
 
-        int nAtlasFeatures = atlasPk.size() / pkIndexes.size();
-        if ( nAtlasFeatures * pkIndexes.size() != atlasPk.size() ) //Test is atlasPk.size() is a multiple of pkIndexes.size(). Bail out if not
+        const int nAtlasFeatures = atlasPk.size() / pkIndexesSize;
+        if ( nAtlasFeatures * pkIndexesSize != atlasPk.size() ) //Test is atlasPk.size() is a multiple of pkIndexesSize. Bail out if not
         {
           throw QgsBadRequestException( QgsServiceException::QGIS_InvalidParameterValue,
                                         QStringLiteral( "Wrong number of ATLAS_PK parameters" ) );
@@ -383,7 +387,7 @@ namespace QgsWms
         if ( nAtlasFeatures > maxAtlasFeatures )
         {
           throw QgsBadRequestException( QgsServiceException::QGIS_InvalidParameterValue,
-                                        QString( "%1 atlas features have been requestet, but the project configuration only allows printing %2 atlas features at a time" )
+                                        QString( "%1 atlas features have been requested, but the project configuration only allows printing %2 atlas features at a time" )
                                         .arg( nAtlasFeatures ).arg( maxAtlasFeatures ) );
         }
 
@@ -399,14 +403,23 @@ namespace QgsWms
 
           filterString.append( "( " );
 
-          for ( int j = 0; j < pkIndexes.size(); ++j )
+          // If the layer has no PK attributes, assume FID
+          if ( pkAttributeNames.isEmpty() )
           {
-            if ( j > 0 )
+            filterString.append( QStringLiteral( "$id = %1" ).arg( atlasPk.at( currentAtlasPk ) ) );
+            ++currentAtlasPk;
+          }
+          else
+          {
+            for ( int j = 0; j < pkIndexes.size(); ++j )
             {
-              filterString.append( " AND " );
+              if ( j > 0 )
+              {
+                filterString.append( " AND " );
+              }
+              filterString.append( QgsExpression::createFieldEqualityExpression( pkAttributeNames.at( j ), atlasPk.at( currentAtlasPk ) ) );
+              ++currentAtlasPk;
             }
-            filterString.append( QString( "\"%1\" = %2" ).arg( pkAttributeNames.at( j ), atlasPk.at( currentAtlasPk ) ) );
-            ++currentAtlasPk;
           }
 
           filterString.append( " )" );
@@ -417,7 +430,7 @@ namespace QgsWms
         atlas->setFilterExpression( filterString, errorString );
         if ( !errorString.isEmpty() )
         {
-          throw QgsException( QStringLiteral( "An error occurred during the Atlas print" ) );
+          throw QgsException( QStringLiteral( "An error occurred during the Atlas print: %1" ).arg( errorString ) );
         }
       }
     }

tests/src/python/test_qgsserver_wms_getprint_atlas.py

@@ -22,9 +22,11 @@
 import urllib.parse
 
 from qgis.testing import unittest
-
+from utilities import unitTestDataPath
 from test_qgsserver import QgsServerTestBase
 
+from qgis.core import QgsProject
+
 
 class TestQgsServerWMSGetPrintAtlas(QgsServerTestBase):
     """QGIS Server WMS Tests for GetPrint atlas request"""
@@ -55,6 +57,25 @@ def test_wms_getprint_atlas_getProjectSettings(self):
         self.assertTrue('atlasEnabled="1"' in str(r))
         self.assertTrue('<PrimaryKeyAttribute>' in str(r))
 
+    def test_wms_getprint_atlas_no_pk(self):
+        """Test issue GH #30817"""
+
+        project = QgsProject()
+        self.assertTrue(project.read(os.path.join(unitTestDataPath(), 'qgis_server', 'bug_gh30817_atlas_pk.qgs')))
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "SERVICE": "WMS",
+            "VERSION": "1.3.0",
+            "REQUEST": "GetPrint",
+            "TEMPLATE": "layout_csv",
+            "TRANSPARENT": "true",
+            "FORMAT": "png",
+            "DPI": "50",
+            "CRS": "EPSG:2056",
+            "ATLAS_PK": "2",
+        }.items())])
+        r, h = self._result(self._execute_request_project(qs, project))
+        self._img_diff_error(r, h, "WMS_GetPrint_Atlas_No_Pk")
+
 
 if __name__ == '__main__':
     unittest.main()