QDataWidgetMapper

The QDataWidgetMapper class provides mapping between a section of a data model to widgets. More

Inheritance diagram of PySide2.QtWidgets.QDataWidgetMapper

Synopsis

Functions

Virtual functions

Slots

Signals

Detailed Description

QDataWidgetMapper can be used to create data-aware widgets by mapping them to sections of an item model. A section is a column of a model if the orientation is horizontal (the default), otherwise a row.

Every time the current index changes, each widget is updated with data from the model via the property specified when its mapping was made. If the user edits the contents of a widget, the changes are read using the same property and written back to the model. By default, each widget’s user property is used to transfer data between the model and the widget. Since Qt 4.3, an additional addMapping() function enables a named property to be used instead of the default user property.

It is possible to set an item delegate to support custom widgets. By default, a QItemDelegate is used to synchronize the model with the widgets.

Let us assume that we have an item model named model with the following contents:

1

Qt Norway

Oslo

2

Qt Australia

Brisbane

3

Qt USA

Palo Alto

4

Qt China

Beijing

5

Qt Germany

Berlin

The following code will map the columns of the model to widgets called mySpinBox , myLineEdit and myCountryChooser :

mapper = QDataWidgetMapper
mapper.setModel(model)
mapper.addMapping(mySpinBox, 0)
mapper.addMapping(myLineEdit, 1)
mapper.addMapping(myCountryChooser, 2)
mapper.toFirst()

After the call to toFirst() , mySpinBox displays the value 1 , myLineEdit displays Qt Norway and myCountryChooser displays Oslo . The navigational functions toFirst() , toNext() , toPrevious() , toLast() and setCurrentIndex() can be used to navigate in the model and update the widgets with contents from the model.

The setRootIndex() function enables a particular item in a model to be specified as the root index - children of this item will be mapped to the relevant widgets in the user interface.

QDataWidgetMapper supports two submit policies, AutoSubmit and ManualSubmit . AutoSubmit will update the model as soon as the current widget loses focus, ManualSubmit will not update the model unless submit() is called. ManualSubmit is useful when displaying a dialog that lets the user cancel all modifications. Also, other views that display the model won’t update until the user finishes all their modifications and submits.

Note that QDataWidgetMapper keeps track of external modifications. If the contents of the model are updated in another module of the application, the widgets are updated as well.

See also

QAbstractItemModel QAbstractItemDelegate

class PySide2.QtWidgets.QDataWidgetMapper([parent=None])
param parent

PySide2.QtCore.QObject

Constructs a new QDataWidgetMapper with parent object parent . By default, the orientation is horizontal and the submit policy is AutoSubmit .

PySide2.QtWidgets.QDataWidgetMapper.SubmitPolicy

This enum describes the possible submit policies a QDataWidgetMapper supports.

Constant

Description

QDataWidgetMapper.AutoSubmit

Whenever a widget loses focus, the widget’s current value is set to the item model.

QDataWidgetMapper.ManualSubmit

The model is not updated until submit() is called.

PySide2.QtWidgets.QDataWidgetMapper.addMapping(widget, section)
Parameters

Adds a mapping between a widget and a section from the model. The section is a column in the model if the orientation is horizontal (the default), otherwise a row.

For the following example, we assume a model myModel that has two columns: the first one contains the names of people in a group, and the second column contains their ages. The first column is mapped to the QLineEdit nameLineEdit , and the second is mapped to the QSpinBox ageSpinBox :

mapper = QDataWidgetMapper()
mapper.setModel(myModel)
mapper.addMapping(nameLineEdit, 0)
mapper.addMapping(ageSpinBox, 1)

Notes:

  • If the widget is already mapped to a section, the old mapping will be replaced by the new one.

  • Only one-to-one mappings between sections and widgets are allowed. It is not possible to map a single section to multiple widgets, or to map a single widget to multiple sections.

PySide2.QtWidgets.QDataWidgetMapper.addMapping(widget, section, propertyName)
Parameters

Essentially the same as addMapping() , but adds the possibility to specify the property to use specifying propertyName .

See also

addMapping()

PySide2.QtWidgets.QDataWidgetMapper.clearMapping()

Clears all mappings.

PySide2.QtWidgets.QDataWidgetMapper.currentIndex()
Return type

int

This property holds the current row or column.

The widgets are populated with with data from the row at index if the orientation is horizontal (the default), otherwise with data from the column at index .

PySide2.QtWidgets.QDataWidgetMapper.currentIndexChanged(index)
Parameters

index – int

PySide2.QtWidgets.QDataWidgetMapper.itemDelegate()
Return type

PySide2.QtWidgets.QAbstractItemDelegate

Returns the current item delegate.

PySide2.QtWidgets.QDataWidgetMapper.mappedPropertyName(widget)
Parameters

widgetPySide2.QtWidgets.QWidget

Return type

PySide2.QtCore.QByteArray

Returns the name of the property that is used when mapping data to the given widget .

PySide2.QtWidgets.QDataWidgetMapper.mappedSection(widget)
Parameters

widgetPySide2.QtWidgets.QWidget

Return type

int

Returns the section the widget is mapped to or -1 if the widget is not mapped.

PySide2.QtWidgets.QDataWidgetMapper.mappedWidgetAt(section)
Parameters

section – int

Return type

PySide2.QtWidgets.QWidget

Returns the widget that is mapped at section , or 0 if no widget is mapped at that section.

PySide2.QtWidgets.QDataWidgetMapper.model()
Return type

PySide2.QtCore.QAbstractItemModel

Returns the current model.

See also

setModel()

PySide2.QtWidgets.QDataWidgetMapper.orientation()
Return type

Orientation

This property holds the orientation of the model.

If the orientation is Horizontal (the default), a widget is mapped to a column of a data model. The widget will be populated with the model’s data from its mapped column and the row that currentIndex() points at.

Use Horizontal for tabular data that looks like this:

1

Qt Norway

Oslo

2

Qt Australia

Brisbane

3

Qt USA

Silicon Valley

4

Qt China

Beijing

5

Qt Germany

Berlin

If the orientation is set to Vertical , a widget is mapped to a row. Calling setCurrentIndex() will change the current column. The widget will be populates with the model’s data from its mapped row and the column that currentIndex() points at.

Use Vertical for tabular data that looks like this:

1

2

3

4

5

Qt Norway

Qt Australia

Qt USA

Qt China

Qt Germany

Oslo

Brisbane

Silicon Valley

Beijing

Berlin

Changing the orientation clears all existing mappings.

PySide2.QtWidgets.QDataWidgetMapper.removeMapping(widget)
Parameters

widgetPySide2.QtWidgets.QWidget

Removes the mapping for the given widget .

PySide2.QtWidgets.QDataWidgetMapper.revert()

Repopulates all widgets with the current data of the model. All unsubmitted changes will be lost.

PySide2.QtWidgets.QDataWidgetMapper.rootIndex()
Return type

PySide2.QtCore.QModelIndex

Returns the current root index.

See also

setRootIndex()

PySide2.QtWidgets.QDataWidgetMapper.setCurrentIndex(index)
Parameters

index – int

This property holds the current row or column.

The widgets are populated with with data from the row at index if the orientation is horizontal (the default), otherwise with data from the column at index .

PySide2.QtWidgets.QDataWidgetMapper.setCurrentModelIndex(index)
Parameters

indexPySide2.QtCore.QModelIndex

Sets the current index to the row of the index if the orientation is horizontal (the default), otherwise to the column of the index .

Calls setCurrentIndex() internally. This convenience slot can be connected to the signal currentRowChanged() or currentColumnChanged() of another view’s selection model .

The following example illustrates how to update all widgets with new data whenever the selection of a QTableView named myTableView changes:

mapper = QDataWidgetMapper()
connect(myTableView.selectionModel(), SIGNAL("currentRowChanged(QModelIndex,QModelIndex)"),
        mapper, SLOT(setCurrentModelIndex(QModelIndex)))

See also

currentIndex()

PySide2.QtWidgets.QDataWidgetMapper.setItemDelegate(delegate)
Parameters

delegatePySide2.QtWidgets.QAbstractItemDelegate

Sets the item delegate to delegate . The delegate will be used to write data from the model into the widget and from the widget to the model, using setEditorData() and setModelData() .

The delegate also decides when to apply data and when to change the editor, using commitData() and closeEditor() .

Warning

You should not share the same instance of a delegate between widget mappers or views. Doing so can cause incorrect or unintuitive editing behavior since each view connected to a given delegate may receive the closeEditor() signal, and attempt to access, modify or close an editor that has already been closed.

See also

itemDelegate()

PySide2.QtWidgets.QDataWidgetMapper.setModel(model)
Parameters

modelPySide2.QtCore.QAbstractItemModel

Sets the current model to model . If another model was set, all mappings to that old model are cleared.

See also

model()

PySide2.QtWidgets.QDataWidgetMapper.setOrientation(aOrientation)
Parameters

aOrientationOrientation

This property holds the orientation of the model.

If the orientation is Horizontal (the default), a widget is mapped to a column of a data model. The widget will be populated with the model’s data from its mapped column and the row that currentIndex() points at.

Use Horizontal for tabular data that looks like this:

1

Qt Norway

Oslo

2

Qt Australia

Brisbane

3

Qt USA

Silicon Valley

4

Qt China

Beijing

5

Qt Germany

Berlin

If the orientation is set to Vertical , a widget is mapped to a row. Calling setCurrentIndex() will change the current column. The widget will be populates with the model’s data from its mapped row and the column that currentIndex() points at.

Use Vertical for tabular data that looks like this:

1

2

3

4

5

Qt Norway

Qt Australia

Qt USA

Qt China

Qt Germany

Oslo

Brisbane

Silicon Valley

Beijing

Berlin

Changing the orientation clears all existing mappings.

PySide2.QtWidgets.QDataWidgetMapper.setRootIndex(index)
Parameters

indexPySide2.QtCore.QModelIndex

Sets the root item to index . This can be used to display a branch of a tree. Pass an invalid model index to display the top-most branch.

See also

rootIndex()

PySide2.QtWidgets.QDataWidgetMapper.setSubmitPolicy(policy)
Parameters

policySubmitPolicy

This property holds the current submit policy.

Changing the current submit policy will revert all widgets to the current data from the model.

PySide2.QtWidgets.QDataWidgetMapper.submit()
Return type

bool

Submits all changes from the mapped widgets to the model.

For every mapped section, the item delegate reads the current value from the widget and sets it in the model. Finally, the model’s submit() method is invoked.

Returns true if all the values were submitted, otherwise false.

Note: For database models, lastError() can be used to retrieve the last error.

PySide2.QtWidgets.QDataWidgetMapper.submitPolicy()
Return type

SubmitPolicy

This property holds the current submit policy.

Changing the current submit policy will revert all widgets to the current data from the model.

PySide2.QtWidgets.QDataWidgetMapper.toFirst()

Populates the widgets with data from the first row of the model if the orientation is horizontal (the default), otherwise with data from the first column.

This is equivalent to calling setCurrentIndex(0) .

PySide2.QtWidgets.QDataWidgetMapper.toLast()

Populates the widgets with data from the last row of the model if the orientation is horizontal (the default), otherwise with data from the last column.

Calls setCurrentIndex() internally.

PySide2.QtWidgets.QDataWidgetMapper.toNext()

Populates the widgets with data from the next row of the model if the orientation is horizontal (the default), otherwise with data from the next column.

Calls setCurrentIndex() internally. Does nothing if there is no next row in the model.

PySide2.QtWidgets.QDataWidgetMapper.toPrevious()

Populates the widgets with data from the previous row of the model if the orientation is horizontal (the default), otherwise with data from the previous column.

Calls setCurrentIndex() internally. Does nothing if there is no previous row in the model.