QgsRelationReferenceWidgetWrapper class

Wraps a relation reference widget.

Contents

Options:

  • ShowForm If True, an embedded form with the referenced feature will be shown.
  • MapIdentification Will offer a map tool to pick a referenced feature on the map canvas. Only use for layers with geometry.
  • ReadOnly If True, will represent the referenced widget in a read-only line edit. Can speed up loading.
  • AllowNULL Will offer NULL as a value.
  • Relation The ID of the relation that will be used to define this widget. ReadOnly

Base classes

class QgsEditorWidgetWrapper
Manages an editor widget Widget and wrapper share the same parent.

Constructors, destructors, conversion operators

QgsRelationReferenceWidgetWrapper(QgsVectorLayer* vl, int fieldIdx, QWidget* editor, QgsMapCanvas* canvas, QgsMessageBar* messageBar, QWidget* parent = nullptr) explicit
Constructor for QgsRelationReferenceWidgetWrapper.

Public functions

auto createWidget(QWidget* parent) -> QWidget* override
This method should create a new widget with the provided parent.
void initWidget(QWidget* editor) override
This method should initialize the editor widget with runtime data.
void showIndeterminateState() override
Sets the widget to display in an indeterminate "mixed value" state.
auto valid() const -> bool override
Returns true if the widget has been properly initialized.
auto value() const -> QVariant override
Will be used to access the widget's value.

Protected functions

void updateConstraintWidgetStatus() override
This should update the widget with a visual cue if a constraint status changed.

Function documentation

QWidget* QgsRelationReferenceWidgetWrapper::createWidget(QWidget* parent) override

This method should create a new widget with the provided parent.

Parameters
parent You should set this parent on the created widget.
Returns A new widget

This will only be called if the form did not already provide a widget, so it is not guaranteed to be called! You should not do initialization stuff, which also has to be done for custom editor widgets inside this method. Things like filling comboboxes and assigning other data which will also be used to make widgets on forms created in the QtDesigner usable should be assigned in initWidget().

void QgsRelationReferenceWidgetWrapper::initWidget(QWidget* editor) override

This method should initialize the editor widget with runtime data.

Parameters
editor The widget which will represent this attribute editor in a form.

Fill your comboboxes here.

void QgsRelationReferenceWidgetWrapper::showIndeterminateState() override

Sets the widget to display in an indeterminate "mixed value" state.

bool QgsRelationReferenceWidgetWrapper::valid() const override

Returns true if the widget has been properly initialized.

Returns Validity status of this widget.

This acts as hint for the calling party if this wrapper can be used after initializing it. If it cannot be used this is a hint to the caller that he may try to find another suitable widget type instead.

QVariant QgsRelationReferenceWidgetWrapper::value() const override

Will be used to access the widget's value.

Returns The current value the widget represents

Read the value from the widget and return it properly formatted to be saved in the attribute.

If an invalid variant is returned this will be interpreted as no change. Be sure to return a NULL QVariant if it should be set to NULL.

void QgsRelationReferenceWidgetWrapper::updateConstraintWidgetStatus() override protected

This should update the widget with a visual cue if a constraint status changed.

By default a stylesheet will be applied on the widget that changes the background color to red.

This can be overwritten in subclasses to allow individual widgets to change the visual cue.