Merge pull request #8034 from m-kuhn/canCommitChanges

Add QgsVectorLayer::allowCommit property

python/core/auto_generated/qgsvectorlayer.sip.in

@@ -2239,6 +2239,8 @@ Configuration and logic to apply automatically on any edit happening on this lay
 .. versionadded:: 3.4
 %End
 
+
+
   public slots:
 
     void select( QgsFeatureId featureId );
@@ -2332,6 +2334,13 @@ This signal is emitted when selection was changed
     void layerModified();
 %Docstring
 This signal is emitted when modifications has been done on layer
+%End
+
+    void allowCommitChanged();
+%Docstring
+Emitted whenever the allowCommitChanged() property of this layer changes.
+
+.. versionadded:: 3.4
 %End
 
     void beforeModifiedCheck() const;

src/core/qgsvectorlayer.cpp

@@ -2926,6 +2926,9 @@ bool QgsVectorLayer::commitChanges()
 
   emit beforeCommitChanges();
 
+  if ( !mAllowCommit )
+    return false;
+
   bool success = mEditBuffer->commitChanges( mCommitErrors );
 
   if ( success )
@@ -4846,6 +4849,20 @@ QgsAbstractVectorLayerLabeling *QgsVectorLayer::readLabelingFromCustomProperties
   return labeling;
 }
 
+bool QgsVectorLayer::allowCommit() const
+{
+  return mAllowCommit;
+}
+
+void QgsVectorLayer::setAllowCommit( bool allowCommit )
+{
+  if ( mAllowCommit == allowCommit )
+    return;
+
+  mAllowCommit = allowCommit;
+  emit allowCommitChanged();
+}
+
 QgsGeometryOptions *QgsVectorLayer::geometryOptions() const
 {
   return mGeometryOptions.get();

src/core/qgsvectorlayer.h

@@ -2010,6 +2010,46 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
      */
     QgsGeometryOptions *geometryOptions() const;
 
+    /**
+     * Controls, if the layer is allowed to commit changes. If this is set to false
+     * it will not be possible to commit changes on this layer. This can be used to
+     * define checks on a layer that need to be pass before the layer can be saved.
+     * If you use this API, make sure that:
+     *
+     *  - the user is visibly informed that his changes were not saved and what he needs
+     *    to do in order to be able to save the changes.
+     *
+     *  - to set the property back to true, once the user has fixed his data.
+     *
+     * When calling \see commitChanges(), this flag is checked just after the
+     * \see beforeCommitChanges() signal is emitted, so it's possible to adjust it from there.
+     *
+     * \note Not available in Python bindings
+     *
+     * \since QGIS 3.4
+     */
+    bool allowCommit() const SIP_SKIP;
+
+    /**
+     * Controls, if the layer is allowed to commit changes. If this is set to false
+     * it will not be possible to commit changes on this layer. This can be used to
+     * define checks on a layer that need to be pass before the layer can be saved.
+     * If you use this API, make sure that:
+     *
+     *  - the user is visibly informed that his changes were not saved and what he needs
+     *    to do in order to be able to save the changes.
+     *
+     *  - to set the property back to true, once the user has fixed his data.
+     *
+     * When calling \see commitChanges(), this flag is checked just after the
+     * \see beforeCommitChanges() signal is emitted, so it's possible to adjust it from there.
+     *
+     * \note Not available in Python bindings
+     *
+     * \since QGIS 3.4
+     */
+    void setAllowCommit( bool allowCommit ) SIP_SKIP;
+
   public slots:
 
     /**
@@ -2102,6 +2142,13 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
     //! This signal is emitted when modifications has been done on layer
     void layerModified();
 
+    /**
+     * Emitted whenever the allowCommitChanged() property of this layer changes.
+     *
+     * \since QGIS 3.4
+     */
+    void allowCommitChanged();
+
     //! Is emitted, when layer is checked for modifications. Use for last-minute additions
     void beforeModifiedCheck() const;
 
@@ -2502,6 +2549,8 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
 
     std::unique_ptr<QgsGeometryOptions> mGeometryOptions;
 
+    bool mAllowCommit = true;
+
     friend class QgsVectorLayerFeatureSource;
 };