Support multiple relation editors via relation widget registry

python/core/auto_generated/qgsattributeeditorelement.sip.in

@@ -113,6 +113,20 @@ Controls if this element should be labeled with a title (field, relation or grou
 Controls if this element should be labeled with a title (field, relation or groupname).
 
 .. versionadded:: 2.18
+%End
+
+    QVariantMap config() const;
+%Docstring
+Returns the editor configuration
+
+.. versionadded:: 3.18
+%End
+
+    void setConfig( const QVariantMap &config );
+%Docstring
+Sets the editor configuration
+
+.. versionadded:: 3.18
 %End
 
   protected:
@@ -351,80 +365,6 @@ Initializes the relation from the id
     virtual QgsAttributeEditorElement *clone( QgsAttributeEditorElement *parent ) const /Factory/;
 
 
- bool showLinkButton() const /Deprecated/;
-%Docstring
-Determines if the "link feature" button should be shown
-
-.. versionadded:: 2.18
-
-.. deprecated:: QGIS 3.16
-   use visibleButtons() instead
-%End
-
- void setShowLinkButton( bool showLinkButton ) /Deprecated/;
-%Docstring
-Determines if the "link feature" button should be shown
-
-.. versionadded:: 2.18
-
-.. deprecated:: QGIS 3.16
-   use setVisibleButtons() instead
-%End
-
- bool showUnlinkButton() const /Deprecated/;
-%Docstring
-Determines if the "unlink feature" button should be shown
-
-.. versionadded:: 2.18
-
-.. deprecated:: QGIS 3.16
-   use visibleButtons() instead
-%End
-
- void setShowUnlinkButton( bool showUnlinkButton ) /Deprecated/;
-%Docstring
-Determines if the "unlink feature" button should be shown
-
-.. versionadded:: 2.18
-
-.. deprecated:: QGIS 3.16
-   use setVisibleButtons() instead
-%End
-
- void setShowSaveChildEditsButton( bool showChildEdits ) /Deprecated/;
-%Docstring
-Determines if the "Save child layer edits" button should be shown
-
-.. versionadded:: 3.14
-
-.. deprecated:: QGIS 3.16
-   use setVisibleButtons() instead
-%End
-
- bool showSaveChildEditsButton() const /Deprecated/;
-%Docstring
-Determines if the "Save child layer edits" button should be shown
-
-.. versionadded:: 3.14
-
-.. deprecated:: QGIS 3.16
-   use visibleButtons() instead
-%End
-
-    void setVisibleButtons( const QgsAttributeEditorRelation::Buttons &buttons );
-%Docstring
-Defines the buttons which are shown
-
-.. versionadded:: 3.16
-%End
-
-    QgsAttributeEditorRelation::Buttons visibleButtons() const;
-%Docstring
-Returns the buttons which are shown
-
-.. versionadded:: 3.16
-%End
-
     bool forceSuppressFormPopup() const;
 %Docstring
 Determines the force suppress form popup status.
@@ -469,6 +409,20 @@ Sets ``label`` for this element
 If it's empty it takes the relation id as label
 
 .. versionadded:: 3.16
+%End
+
+    QString relationWidgetTypeId() const;
+%Docstring
+Returns the current relation widget type id
+
+.. versionadded:: 3.18
+%End
+
+    void setRelationWidgetTypeId( const QString &relationWidgetTypeId );
+%Docstring
+Sets the relation widget type
+
+.. versionadded:: 3.18
 %End
 
 };

python/gui/auto_additions/qgsrelationeditorwidget.py

@@ -0,0 +1,4 @@
+# The following has been generated automatically from src/gui/qgsrelationeditorwidget.h
+QgsRelationEditorWidget.Button.baseClass = QgsRelationEditorWidget
+QgsRelationEditorWidget.Buttons.baseClass = QgsRelationEditorWidget
+Buttons = QgsRelationEditorWidget  # dirty hack since SIP seems to introduce the flags in module

python/gui/auto_generated/editorwidgets/qgsrelationwidgetwrapper.sip.in

@@ -18,7 +18,23 @@ class QgsRelationWidgetWrapper : QgsWidgetWrapper
 %End
   public:
 
-    explicit QgsRelationWidgetWrapper( QgsVectorLayer *vl, const QgsRelation &relation, QWidget *editor = 0, QWidget *parent /TransferThis/ = 0 );
+    QgsRelationWidgetWrapper(
+      QgsVectorLayer *vl,
+      const QgsRelation &relation,
+      QWidget *editor /Constrained/ = 0,
+      QWidget *parent /TransferThis,Constrained/  = 0
+    );
+%Docstring
+Constructor for QgsRelationWidgetWrapper
+%End
+
+    QgsRelationWidgetWrapper(
+      const QString &relationEditorName,
+      QgsVectorLayer *vl,
+      const QgsRelation &relation,
+      QWidget *editor = 0,
+      QWidget *parent /TransferThis/ = 0
+    );
 %Docstring
 Constructor for QgsRelationWidgetWrapper
 %End
@@ -99,18 +115,41 @@ Determines if the "Save child layer edits" button should be shown
    use visibleButtons() instead
 %End
 
-    void setVisibleButtons( const QgsAttributeEditorRelation::Buttons &buttons );
+ void setVisibleButtons( const QgsAttributeEditorRelation::Buttons &buttons ) /Deprecated/;
 %Docstring
 Defines the buttons which are shown
 
 .. versionadded:: 3.16
+
+.. deprecated:: QGIS 3.18
+   use setWidgetConfig() instead
 %End
 
-    QgsAttributeEditorRelation::Buttons visibleButtons() const;
+ QgsAttributeEditorRelation::Buttons visibleButtons() const /Deprecated/;
 %Docstring
 Returns the buttons which are shown
 
 .. versionadded:: 3.16
+
+.. deprecated:: QGIS 3.18
+   use widgetConfig() instead
+%End
+
+
+    void setWidgetConfig( const QVariantMap &config );
+%Docstring
+Will set the config of this widget wrapper to the specified config.
+
+:param config: The config for this wrapper
+
+.. versionadded:: 3.18
+%End
+
+    QVariantMap widgetConfig() const;
+%Docstring
+Returns the whole widget config
+
+.. versionadded:: 3.18
 %End
 
     bool forceSuppressFormPopup() const;