make deleteStyleFromDatabase consistent with other vectorlayer's methods

python/core/qgsvectordataprovider.sip

@@ -413,11 +413,6 @@ class QgsVectorDataProvider : QgsDataProvider
      */
     virtual bool isDeleteStyleFromDBSupported() const;
 
-    /**
-     * Deletes an existing style from the provider
-     */
-    virtual void deleteStyleById( const QString& uri, QString styleId, QString& errCause );
-
     static QVariant convertValue( QVariant::Type type, const QString& value );
 
     /**

python/core/qgsvectorlayer.sip

@@ -684,6 +684,11 @@ class QgsVectorLayer : QgsMapLayer, QgsExpressionContextGenerator
      */
     virtual QString getStyleFromDatabase( const QString& styleId, QString &msgError /Out/ );
 
+    /**
+     * Will delete the named style corresponding to style id provided from the database
+     */
+    virtual void deleteStyleFromDatabase( const QString& styleId, QString &msgError /Out/ );
+
     /**
      * Load a named style from file/local db/datasource db
      * @param theURI the URI of the style or the URI of the layer

src/app/qgsloadstylefromdbdialog.cpp

@@ -171,7 +171,8 @@ void QgsLoadStyleFromDBDialog::deleteStyleFromDB()
     return;
 
   uri = mLayer->dataProvider()->dataSourceUri();
-  mLayer->dataProvider()->deleteStyleById( uri, mSelectedStyleId, msgError );
+  //  mLayer->dataProvider()->deleteStyleById( uri, mSelectedStyleId, msgError );
+  mLayer->deleteStyleFromDatabase( mSelectedStyleId, msgError );
 
   if ( !msgError.isNull() )
   {

src/core/qgsvectordataprovider.cpp

@@ -700,14 +700,6 @@ bool QgsVectorDataProvider::isDeleteStyleFromDBSupported() const
   return false;
 }
 
-void QgsVectorDataProvider::deleteStyleById( const QString& uri, QString styleId, QString& errCause ) const
-{
-  Q_UNUSED( uri );
-  Q_UNUSED( styleId );
-  Q_UNUSED( errCause );
-  return;
-}
-
 void QgsVectorDataProvider::pushError( const QString& msg ) const
 {
   QgsDebugMsg( msg );

src/core/qgsvectordataprovider.h

@@ -476,11 +476,6 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider
      */
     virtual bool isDeleteStyleFromDBSupported() const;
 
-    /**
-     * Deletes an existing style from the provider
-     */
-    virtual void deleteStyleById( const QString& uri, QString styleId, QString& errCause ) const;
-
     static QVariant convertValue( QVariant::Type type, const QString& value );
 
     /**

src/core/qgsvectorlayer.cpp

@@ -120,6 +120,12 @@ typedef QString getStyleById_t(
   QString& errCause
 );
 
+typedef void deleteStyleById_t(
+  const QString& uri,
+  QString styleID,
+  QString& errCause
+);
+
 QgsVectorLayer::QgsVectorLayer( const QString& vectorLayerPath,
                                 const QString& baseName,
                                 const QString& providerKey,
@@ -4335,6 +4341,27 @@ QString QgsVectorLayer::getStyleFromDatabase( const QString& styleId, QString &m
   return getStyleByIdMethod( mDataSource, styleId, msgError );
 }
 
+void QgsVectorLayer::deleteStyleFromDatabase( const QString& styleId, QString &msgError )
+{
+  QgsProviderRegistry * pReg = QgsProviderRegistry::instance();
+  QLibrary *myLib = pReg->providerLibrary( mProviderKey );
+  if ( !myLib )
+  {
+    msgError = QObject::tr( "Unable to load %1 provider" ).arg( mProviderKey );
+    return;
+  }
+  deleteStyleById_t* deleteStyleByIdMethod = reinterpret_cast< deleteStyleById_t * >( cast_to_fptr( myLib->resolve( "deleteStyleById" ) ) );
+
+  if ( !deleteStyleByIdMethod )
+  {
+    delete myLib;
+    msgError = QObject::tr( "Provider %1 has no %2 method" ).arg( mProviderKey, QStringLiteral( "deleteStyleById" ) );
+    return;
+  }
+
+  return deleteStyleByIdMethod( mDataSource, styleId, msgError );
+}
+
 
 void QgsVectorLayer::saveStyleToDatabase( const QString& name, const QString& description,
     bool useAsDefault, const QString& uiFileContent, QString &msgError )

src/core/qgsvectorlayer.h

@@ -785,6 +785,11 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
      */
     virtual QString getStyleFromDatabase( const QString& styleId, QString &msgError );
 
+    /**
+     * Will delete the named style corresponding to style id provided from the database
+     */
+    virtual void deleteStyleFromDatabase( const QString& styleId, QString &msgError );
+
     /**
      * Load a named style from file/local db/datasource db
      * @param theURI the URI of the style or the URI of the layer

src/providers/postgres/qgspostgresprovider.cpp

@@ -4632,7 +4632,7 @@ QGISEXTERN int listStyles( const QString &uri, QStringList &ids, QStringList &na
   return numberOfRelatedStyles;
 }
 
-void QgsPostgresProvider::deleteStyleById( const QString &uri, QString styleId, QString &errCause ) const
+QGISEXTERN void deleteStyleById( const QString &uri, QString styleId, QString &errCause )
 {
   QgsDataSourceUri dsUri( uri );
 
@@ -4655,6 +4655,9 @@ void QgsPostgresProvider::deleteStyleById( const QString &uri, QString styleId,
       errCause = QObject::tr( "Error executing the delete query. The query was logged" );
     }
   }
+
+  conn->unref();
+
 }
 
 QGISEXTERN QString getStyleById( const QString& uri, QString styleId, QString& errCause )

src/providers/postgres/qgspostgresprovider.h

@@ -133,7 +133,6 @@ class QgsPostgresProvider : public QgsVectorDataProvider
     bool isValid() const override;
     virtual bool isSaveAndLoadStyleToDBSupported() const override { return true; }
     virtual bool isDeleteStyleFromDBSupported() const override { return true; }
-    void deleteStyleById( const QString& uri, QString styleId, QString& errCause ) const override;
     QgsAttributeList attributeIndexes() const override;
     QgsAttributeList pkAttributeIndexes() const override { return mPrimaryKeyAttrs; }
     QString defaultValueClause( int fieldId ) const override;

tests/src/python/test_provider_postgres.py

@@ -663,19 +663,20 @@ class TestPyQgsPostgresProvider(unittest.TestCase, ProviderTestCase):
         status = vl.loadNamedStyle(mFilePath)
         self.assertTrue(status)
 
-        errorMsg = vl.saveStyleToDatabase("name", "description", False, "")
+        errorMsg = vl.saveStyleToDatabase("by day", "faded greens and elegant patterns", False, "")
         self.assertEqual(errorMsg, "")
 
-        qml, errmsg = vl.getStyleFromDatabase("not_existing")
+        # the style id should be "1", not "by day"
+        qml, errmsg = vl.getStyleFromDatabase("by day")
         self.assertEqual(qml, "")
         self.assertNotEqual(errmsg, "")
 
         related_count, idlist, namelist, desclist, errmsg = vl.listStylesInDatabase()
         self.assertEqual(related_count, 1)
         self.assertEqual(errmsg, "")
-        self.assertEqual(idlist, ['1'])
-        self.assertEqual(namelist, ['name'])
-        self.assertEqual(desclist, ['description'])
+        self.assertEqual(idlist, ["1"])
+        self.assertEqual(namelist, ["by day"])
+        self.assertEqual(desclist, ["faded greens and elegant patterns"])
 
         qml, errmsg = vl.getStyleFromDatabase("100")
         self.assertEqual(qml, "")
@@ -685,8 +686,10 @@ class TestPyQgsPostgresProvider(unittest.TestCase, ProviderTestCase):
         self.assertTrue(qml.startswith('<!DOCTYPE qgis'), qml)
         self.assertEqual(errmsg, "")
 
-        uri = vl.dataProvider().dataSourceUri()
-        vl.dataProvider().deleteStyleById(uri, "1", errmsg)
+        errmsg = vl.deleteStyleFromDatabase("101")
+        self.assertEqual(errmsg, "")
+
+        errmsg = vl.deleteStyleFromDatabase("1")
         self.assertEqual(errmsg, "")
 
         # table layer_styles does exit, but is now empty