Rework vector joins so they do not use QgsProject::instance()

The basic idea is to split reading of XML definition and resolution of layer IDs into layers.

Also includes some cleanups in QgsProject and improvements in QgsVectorLayerJoinInfo.

doc/api_break.dox

@@ -179,6 +179,7 @@ Renamed Classes        {#qgis_api_break_3_0_renamed_classes}
 <tr><td>QgsVectorGradientColorRampV2Dialog<td>QgsGradientColorRampDialog
 <tr><td>QgsVectorGradientColorRampV2DialogBase<td>QgsGradientColorRampDialogBase
 <tr><td>QgsVectorGradientRampV2<td>QgsVectorGradientRamp
+<tr><td>QgsVectorJoinInfo<td>QgsVectorLayerJoinInfo
 <tr><td>QgsVectorLayersetRendererV2<td>QgsVectorLayersetRenderer
 <tr><td>QgsVectorRandomColorRampV2<td>QgsLimitedRandomColorRamp
 <tr><td>QgsVectorRandomColorRampV2Dialog<td>QgsLimitedRandomColorRampDialog
@@ -1531,6 +1532,7 @@ QgsProject        {#qgis_api_break_3_0_QgsProject}
 - read( QDomNode& layerNode ) was renamed to readLayer( const QDomNode& layerNode ).
 - read( const QFileInfo& file ) was replaced by read( const QString& filename ).
 - write( const QFileInfo& file ) was replaced by write( const QString& filename ).
+- createEmbeddedLayer() does not take vectorLayerList as the third parameter anymore.
 
 
 QgsProjectPropertyValue        {#qgis_api_break_3_0_QgsProjectPropertyValue}
@@ -1887,6 +1889,13 @@ QGIS 3.0 defaultValue() only returns literal, constant defaultValues. A new meth
 has been added which returns the SQL clause fragments which must be evaluated by the provider itself.
 
 
+QgsVectorJoinInfo   {#qgis_api_break_3_0_QgsVectorJoinInfo}
+-----------------
+
+- class has been renamed to QgsVectorLayerJoinInfo
+- member variables are now accessible through pairs of getters and setters rather than using direct read/write
+
+
 QgsVectorLayer        {#qgis_api_break_3_0_QgsVectorLayer}
 --------------
 
@@ -1926,6 +1935,9 @@ displayExpression instead. For the map tip use mapTipTemplate() instead.
 - loadNamedStyle(): theResultFlag argument is correctly declared as output argument
 - The duplicate selectionChanged() signal was removed. Use selectionChanged( const QgsFeatureIds&, const QgsFeatureIds&, const bool ) instead.
 - featureCount() now requires a legend key string instead of a QgsSymbol pointer argument.
+- createJoinCaches() has been removed. Caches are created/updated when needed internally.
+- checkJoinLayerRemove() has been removed. Joins are removed internally when joined layer is deleted.
+- readXml() does not resolve references to joined layers. Call resolveReferences() when joined layers are available.
 
 QgsVectorLayerEditBuffer        {#qgis_api_break_3_0_QgsVectorLayerEditBuffer}
 ------------------------
@@ -1953,6 +1965,12 @@ in code which previously passed a null pointer to QgsVectorLayerImport.
 - ErrUserCancelled (ImportError enum value) has been renamed to ErrUserCanceled  <!--#spellok-->
 
 
+QgsVectorLayerJoinBuffer        {#qgis_api_break_3_0_QgsVectorLayerJoinBuffer}
+------------------------
+
+- readXml() does not resolve layer IDs to layers anymore. You need to call resolveReferences() afterwards.
+
+
 QgsVectorLayerUndoCommand        {#qgis_api_break_3_0_QgsVectorLayerUndoCommand}
 -------------------------
 

python/core/core.sip

@@ -155,6 +155,7 @@
 %Include qgsvectorlayereditpassthrough.sip
 %Include qgsvectorlayerimport.sip
 %Include qgsvectorlayerjoinbuffer.sip
+%Include qgsvectorlayerjoininfo.sip
 %Include qgsvectorlayertools.sip
 %Include qgsvectorlayerundocommand.sip
 %Include qgsvectorlayerutils.sip

python/core/qgsvectorlayer.sip

@@ -3,46 +3,6 @@ typedef QList<int> QgsAttributeList;
 typedef QSet<int> QgsAttributeIds;
 
 
-struct QgsVectorJoinInfo
-{
-%TypeHeaderCode
-#include "qgsvectorlayer.h"
-%End
-  QgsVectorJoinInfo();
-
-  /** Join field in the target layer*/
-  QString targetFieldName;
-  /** Source layer*/
-  QString joinLayerId;
-  /** Join field in the source layer*/
-  QString joinFieldName;
-  /** True if the join is cached in virtual memory*/
-  bool memoryCache;
-  /** True if the cached join attributes need to be updated*/
-  bool cacheDirty;
-
-  /** Cache for joined attributes to provide fast lookup (size is 0 if no memory caching)
-   * @note not available in python bindings
-   */
-  // QHash< QString, QgsAttributeMap> cachedAttributes;
-
-  /** An optional prefix. If it is a Null string "{layername}_" will be used
-   * @note Added in 2.8
-   */
-  QString prefix;
-
-  bool operator==( const QgsVectorJoinInfo& other ) const;
-
-  /** Set subset of fields to be used from joined layer. Takes ownership of the passed pointer. Null pointer tells to use all fields.
-    @note added in 2.6 */
-  void setJoinFieldNamesSubset( QStringList* fieldNamesSubset /Transfer/ );
-  /** Get subset of fields to be used from joined layer. All fields will be used if null is returned.
-    @note added in 2.6 */
-  QStringList* joinFieldNamesSubset() const;
-};
-
-
-
 /** \ingroup core
  * Represents a vector layer which manages a vector based data sets.
  *
@@ -413,7 +373,7 @@ class QgsVectorLayer : QgsMapLayer, QgsExpressionContextGenerator
     /** Joins another vector layer to this layer
       @param joinInfo join object containing join layer id, target and source field
       @note since 2.6 returns bool indicating whether the join can be added */
-    bool addJoin( const QgsVectorJoinInfo& joinInfo );
+    bool addJoin( const QgsVectorLayerJoinInfo& joinInfo );
 
     /** Removes a vector layer join
       @returns true if join was found and successfully removed */
@@ -424,7 +384,7 @@ class QgsVectorLayer : QgsMapLayer, QgsExpressionContextGenerator
      * @note added 2.14.7
      */
     QgsVectorLayerJoinBuffer* joinBuffer();
-    const QList<QgsVectorJoinInfo> vectorJoins() const;
+    const QList<QgsVectorLayerJoinInfo> vectorJoins() const;
 
     /**
      * Sets the list of dependencies.
@@ -656,6 +616,11 @@ class QgsVectorLayer : QgsMapLayer, QgsExpressionContextGenerator
      */
     virtual bool writeXml( QDomNode & layer_node, QDomDocument & doc ) const;
 
+    /** Resolve references to other layers (kept as layer IDs after reading XML) into layer objects.
+     * @note added in 3.0
+     */
+    void resolveReferences( QgsProject* project );
+
     /**
      * Save named and sld style of the layer to the style table in the db.
      * @param name
@@ -1216,10 +1181,6 @@ class QgsVectorLayer : QgsMapLayer, QgsExpressionContextGenerator
     /** Assembles mUpdatedFields considering provider fields, joined fields and added fields */
     void updateFields();
 
-    /** Caches joined attributes if required (and not already done) */
-    // marked as const as these are just caches, and need to be created from const accessors
-    void createJoinCaches() const;
-
     /** Returns the calculated default value for the specified field index. The default
      * value may be taken from a client side default value expression (see setDefaultValueExpression())
      * or taken from the underlying data provider.
@@ -1539,9 +1500,6 @@ class QgsVectorLayer : QgsMapLayer, QgsExpressionContextGenerator
      */
     virtual void updateExtents();
 
-    /** Check if there is a join with a layer that will be removed */
-    void checkJoinLayerRemove( const QString& theLayerId );
-
     /**
      * Make layer editable.
      * This starts an edit session on this layer. Changes made in this edit session will not

python/core/qgsvectorlayerjoinbuffer.sip

@@ -10,7 +10,7 @@ class QgsVectorLayerJoinBuffer : QObject
     /** Joins another vector layer to this layer
       @param joinInfo join object containing join layer id, target and source field
       @return (since 2.6) whether the join was successfully added */
-    bool addJoin( const QgsVectorJoinInfo& joinInfo );
+    bool addJoin( const QgsVectorLayerJoinInfo& joinInfo );
 
     /** Removes a vector layer join
       @returns true if join was found and successfully removed */
@@ -30,20 +30,24 @@ class QgsVectorLayerJoinBuffer : QObject
     /** Reads joins from project file*/
     void readXml( const QDomNode& layer_node );
 
+    //! Resolves layer IDs of joined layers using given project's available layers
+    //! @note added in 3.0
+    void resolveReferences( QgsProject* project );
+
     /** Quick way to test if there is any join at all*/
     bool containsJoins() const;
 
-    const QList< QgsVectorJoinInfo >& vectorJoins() const;
+    const QList< QgsVectorLayerJoinInfo >& vectorJoins() const;
 
     /** Finds the vector join for a layer field index.
       @param index this layers attribute index
       @param fields fields of the vector layer (including joined fields)
       @param sourceFieldIndex Output: field's index in source layer */
-    const QgsVectorJoinInfo* joinForFieldIndex( int index, const QgsFields& fields, int& sourceFieldIndex /Out/ ) const;
+    const QgsVectorLayerJoinInfo* joinForFieldIndex( int index, const QgsFields& fields, int& sourceFieldIndex /Out/ ) const;
 
     //! Find out what is the first index of the join within fields. Returns -1 if join is not present
     //! @note added in 2.6
-    int joinedFieldsOffset( const QgsVectorJoinInfo* info, const QgsFields& fields );
+    int joinedFieldsOffset( const QgsVectorLayerJoinInfo* info, const QgsFields& fields );
 
     //! Return a vector of indices for use in join based on field names from the layer
     //! @note added in 2.6

python/core/qgsvectorlayerjoininfo.sip

@@ -0,0 +1,49 @@
+
+class QgsVectorLayerJoinInfo
+{
+%TypeHeaderCode
+#include "qgsvectorlayerjoininfo.h"
+%End
+
+  public:
+    QgsVectorLayerJoinInfo();
+
+    //! Sets weak reference to the joined layer
+    void setJoinLayer( QgsVectorLayer* layer );
+    //! Returns joined layer (may be null if the reference was set by layer ID and not resolved yet)
+    QgsVectorLayer* joinLayer() const;
+
+    //! Sets ID of the joined layer. It will need to be overwritten by setJoinLayer() to a reference to real layer
+    void setJoinLayerId( const QString& layerId );
+    //! ID of the joined layer - may be used to resolve reference to the joined layer
+    QString joinLayerId() const;
+
+    //! Sets name of the field of our layer that will be used for join
+    void setTargetFieldName( const QString& fieldName );
+    //! Returns name of the field of our layer that will be used for join
+    QString targetFieldName() const;
+
+    //! Sets name of the field of joined layer that will be used for join
+    void setJoinFieldName( const QString& fieldName );
+    //! Returns name of the field of joined layer that will be used for join
+    QString joinFieldName() const;
+
+    //! Sets prefix of fields from the joined layer. If null, joined layer's name will be used.
+    void setPrefix( const QString& prefix );
+    //! Returns prefix of fields from the joined layer. If null, joined layer's name will be used.
+    QString prefix() const;
+
+    //! Sets whether values from the joined layer should be cached in memory to speed up lookups
+    void setUsingMemoryCache( bool enabled );
+    //! Returns whether values from the joined layer should be cached in memory to speed up lookups
+    bool isUsingMemoryCache() const;
+
+    bool operator==( const QgsVectorLayerJoinInfo& other ) const;
+
+    /** Set subset of fields to be used from joined layer. Takes ownership of the passed pointer. Null pointer tells to use all fields.
+      @note added in 2.6 */
+    void setJoinFieldNamesSubset( QStringList* fieldNamesSubset /Transfer/ );
+    /** Get subset of fields to be used from joined layer. All fields will be used if null is returned.
+      @note added in 2.6 */
+    QStringList* joinFieldNamesSubset() const;
+};

src/app/qgisapp.cpp

@@ -247,6 +247,7 @@
 #include "qgsvirtuallayerdefinitionutils.h"
 #include "qgstransaction.h"
 #include "qgstransactiongroup.h"
+#include "qgsvectorlayerjoininfo.h"
 #include "qgsvectorlayerutils.h"
 #include "qgshelp.h"
 
@@ -8543,7 +8544,7 @@ void QgisApp::duplicateLayers( const QList<QgsMapLayer *>& lyrList )
           QgsExpressionContextUtils::setLayerVariable( dupVLayer, variableName, varValue );
         }
 
-        Q_FOREACH ( const QgsVectorJoinInfo& join, vlayer->vectorJoins() )
+        Q_FOREACH ( const QgsVectorLayerJoinInfo& join, vlayer->vectorJoins() )
           dupVLayer->addJoin( join );
 
         for ( int fld = 0; fld < vlayer->fields().count(); fld++ )
@@ -9509,7 +9510,6 @@ void QgisApp::embedLayers()
 
     //layer ids
     QList<QDomNode> brokenNodes;
-    QList< QPair< QgsVectorLayer*, QDomElement > > vectorLayerList;
 
     // resolve dependencies
     QgsLayerDefinition::DependencySorter depSorter( projectFile );
@@ -9520,7 +9520,7 @@ void QgisApp::embedLayers()
       Q_FOREACH ( const QString& selId, layerIds )
       {
         if ( selId == id )
-          QgsProject::instance()->createEmbeddedLayer( selId, projectFile, brokenNodes, vectorLayerList );
+          QgsProject::instance()->createEmbeddedLayer( selId, projectFile, brokenNodes );
       }
     }
 

src/app/qgsjoindialog.cpp

@@ -20,6 +20,7 @@
 #include "qgsproject.h"
 #include "qgsvectordataprovider.h"
 #include "qgsvectorlayer.h"
+#include "qgsvectorlayerjoininfo.h"
 #include "qgsmaplayercombobox.h"
 #include "qgsfieldcombobox.h"
 
@@ -66,20 +67,20 @@ QgsJoinDialog::~QgsJoinDialog()
 {
 }
 
-void QgsJoinDialog::setJoinInfo( const QgsVectorJoinInfo& joinInfo )
+void QgsJoinDialog::setJoinInfo( const QgsVectorLayerJoinInfo& joinInfo )
 {
-  mJoinLayerComboBox->setLayer( QgsProject::instance()->mapLayer( joinInfo.joinLayerId ) );
-  mJoinFieldComboBox->setField( joinInfo.joinFieldName );
-  mTargetFieldComboBox->setField( joinInfo.targetFieldName );
-  mCacheInMemoryCheckBox->setChecked( joinInfo.memoryCache );
-  if ( joinInfo.prefix.isNull() )
+  mJoinLayerComboBox->setLayer( joinInfo.joinLayer() );
+  mJoinFieldComboBox->setField( joinInfo.joinFieldName() );
+  mTargetFieldComboBox->setField( joinInfo.targetFieldName() );
+  mCacheInMemoryCheckBox->setChecked( joinInfo.isUsingMemoryCache() );
+  if ( joinInfo.prefix().isNull() )
   {
     mUseCustomPrefix->setChecked( false );
   }
   else
   {
     mUseCustomPrefix->setChecked( true );
-    mCustomPrefix->setText( joinInfo.prefix );
+    mCustomPrefix->setText( joinInfo.prefix() );
   }
 
   QStringList* lst = joinInfo.joinFieldNamesSubset();
@@ -102,21 +103,18 @@ void QgsJoinDialog::setJoinInfo( const QgsVectorJoinInfo& joinInfo )
   }
 }
 
-QgsVectorJoinInfo QgsJoinDialog::joinInfo() const
+QgsVectorLayerJoinInfo QgsJoinDialog::joinInfo() const
 {
-  QgsVectorJoinInfo info;
-  if ( mJoinLayerComboBox->currentLayer() )
-    info.joinLayerId = mJoinLayerComboBox->currentLayer()->id();
-  info.joinFieldName = mJoinFieldComboBox->currentField();
-  info.targetFieldName = mTargetFieldComboBox->currentField();
-  info.memoryCache = mCacheInMemoryCheckBox->isChecked();
-  info.targetFieldIndex = -1;
-  info.joinFieldIndex = -1;
+  QgsVectorLayerJoinInfo info;
+  info.setJoinLayer( qobject_cast<QgsVectorLayer*>( mJoinLayerComboBox->currentLayer() ) );
+  info.setJoinFieldName( mJoinFieldComboBox->currentField() );
+  info.setTargetFieldName( mTargetFieldComboBox->currentField() );
+  info.setUsingMemoryCache( mCacheInMemoryCheckBox->isChecked() );
 
   if ( mUseCustomPrefix->isChecked() )
-    info.prefix = mCustomPrefix->text();
+    info.setPrefix( mCustomPrefix->text() );
   else
-    info.prefix = QString::null;
+    info.setPrefix( QString::null );
 
   if ( mUseJoinFieldsSubset->isChecked() )
   {

src/app/qgsjoindialog.h

@@ -22,7 +22,7 @@
 #include "qgis_app.h"
 
 class QgsVectorLayer;
-struct QgsVectorJoinInfo;
+class QgsVectorLayerJoinInfo;
 
 class APP_EXPORT QgsJoinDialog: public QDialog, private Ui::QgsJoinDialogBase
 {
@@ -32,10 +32,10 @@ class APP_EXPORT QgsJoinDialog: public QDialog, private Ui::QgsJoinDialogBase
     ~QgsJoinDialog();
 
     //! Configure the dialog for an existing join
-    void setJoinInfo( const QgsVectorJoinInfo& joinInfo );
+    void setJoinInfo( const QgsVectorLayerJoinInfo& joinInfo );
 
     //! Returns the join info
-    QgsVectorJoinInfo joinInfo() const;
+    QgsVectorLayerJoinInfo joinInfo() const;
 
     //! Returns true if user wants to create an attribute index on the join field
     bool createAttributeIndex() const;