Make setEditable() return true/false to indicate success/error

Author: wonder-sk

python/core/raster/qgsrasterdataprovider.sip

@@ -242,13 +242,14 @@ class QgsRasterDataProvider : QgsDataProvider, QgsRasterInterface
 
     /** Turns on/off editing mode of the provider. When in editing mode, it is possible
      * to overwrite data of the provider using writeBlock() calls.
-     * @note Only some providers support editing mode and even those may fail to turn turn
-     * the underlying data source into editing mode, so it is necessery to check afterwards
-     * with isEditable() whether the operation was successful.
+     * @note Only some providers support editing mode and even those may fail to turn
+     * the underlying data source into editing mode, so it is necessery to check the return
+     * value whether the operation was successful.
+     * @returns true if the switch to/from editing mode was successful
      * @see isEditable(), writeBlock()
      * @note added in QGIS 3.0
      */
-    virtual void setEditable( bool enabled );
+    virtual bool setEditable( bool enabled );
 
     /** Writes into the provider datasource*/
     // TODO: add data type (may be defferent from band type)

src/core/raster/qgsrasterdataprovider.h

@@ -360,13 +360,14 @@ class CORE_EXPORT QgsRasterDataProvider : public QgsDataProvider, public QgsRast
 
     /** Turns on/off editing mode of the provider. When in editing mode, it is possible
      * to overwrite data of the provider using writeBlock() calls.
-     * @note Only some providers support editing mode and even those may fail to turn turn
-     * the underlying data source into editing mode, so it is necessery to check afterwards
-     * with isEditable() whether the operation was successful.
+     * @note Only some providers support editing mode and even those may fail to turn
+     * the underlying data source into editing mode, so it is necessery to check the return
+     * value whether the operation was successful.
+     * @returns true if the switch to/from editing mode was successful
      * @see isEditable(), writeBlock()
      * @note added in QGIS 3.0
      */
-    virtual void setEditable( bool enabled ) { Q_UNUSED( enabled ); }
+    virtual bool setEditable( bool enabled ) { Q_UNUSED( enabled ); return false; }
 
     //! Writes into the provider datasource
     // TODO: add data type (may be defferent from band type)

src/providers/gdal/qgsgdalprovider.cpp

@@ -2933,16 +2933,16 @@ bool QgsGdalProvider::isEditable() const
   return mUpdate;
 }
 
-void QgsGdalProvider::setEditable( bool enabled )
+bool QgsGdalProvider::setEditable( bool enabled )
 {
   if ( enabled == mUpdate )
-    return;
+    return false;
 
   if ( !mValid )
-    return;
+    return false;
 
   if ( mGdalDataset != mGdalBaseDataset )
-    return;  // ignore the case of warped VRT for now (more complicated setup)
+    return false;  // ignore the case of warped VRT for now (more complicated setup)
 
   closeDataset();
 
@@ -2954,12 +2954,13 @@ void QgsGdalProvider::setEditable( bool enabled )
   {
     QString msg = QStringLiteral( "Cannot reopen GDAL dataset %1:\n%2" ).arg( dataSourceUri(), QString::fromUtf8( CPLGetLastErrorMsg() ) );
     appendError( ERRMSG( msg ) );
-    return;
+    return false;
   }
 
   //Since we are not a virtual warped dataset, mGdalDataSet and mGdalBaseDataset are supposed to be the same
   mGdalDataset = mGdalBaseDataset;
   mValid = true;
+  return true;
 }
 
 // pyramids resampling

src/providers/gdal/qgsgdalprovider.h

@@ -149,7 +149,7 @@ class QgsGdalProvider : public QgsRasterDataProvider, QgsGdalProviderBase
     static QMap<QString, QString> supportedMimes();
 
     bool isEditable() const override;
-    void setEditable( bool enabled ) override;
+    bool setEditable( bool enabled ) override;
     bool write( void* data, int band, int width, int height, int xOffset, int yOffset ) override;
 
     bool setNoDataValue( int bandNo, double noDataValue ) override;

tests/src/core/testqgsrasterblock.cpp

@@ -184,15 +184,22 @@ void TestQgsRasterBlock::testWrite()
   res = rlayer->dataProvider()->writeBlock( block4, 1 );
   QVERIFY( !res );
 
-  // make the provider editable
+  // some sanity checks
   QVERIFY( !rlayer->dataProvider()->isEditable() );
-  rlayer->dataProvider()->setEditable( true );
+  res = rlayer->dataProvider()->setEditable( false );
+  QVERIFY( !res );
+
+  // make the provider editable
+  res = rlayer->dataProvider()->setEditable( true );
+  QVERIFY( res );
   QVERIFY( rlayer->dataProvider()->isEditable() );
 
   res = rlayer->dataProvider()->writeBlock( block4, 1 );
   QVERIFY( res );
 
-  rlayer->dataProvider()->setEditable( false );
+  // finish the editing session
+  res = rlayer->dataProvider()->setEditable( false );
+  QVERIFY( res );
   QVERIFY( !rlayer->dataProvider()->isEditable() );
 
   // verify the change is there