Class: QgsFieldModel

The QgsFieldModel class is a model to display the list of fields in widgets (optionally associated with a vector layer).

If allowed, expressions might be added to the end of the model. It can be associated with a QgsMapLayerModel to dynamically display a layer and its fields.

Class Hierarchy

Base classes

QAbstractItemModel
QObject

Enums

CustomRole	Custom model roles.
FieldRoles	alias of CustomRole

Methods

allowEmptyFieldName	Returns True if the model allows the empty field ("not set") choice.
allowExpression	Returns True if the model allows custom expressions to be created and displayed.
fields	Returns the fields currently shown in the model.
indexFromName	Returns the index corresponding to a given fieldName.
isField	Returns True if a string represents a field reference, or False if it is an expression consisting of more than direct field reference.
layer	Returns the layer associated with the model.
removeExpression	Removes any custom expression from the model.
setAllowEmptyFieldName	Sets whether an optional empty field ("not set") option is present in the model.
setAllowExpression	Sets whether custom expressions are accepted and displayed in the model.
setExpression	Sets a single expression to be added after the fields at the end of the model.
setFields	Manually sets the fields to use for the model.
setLayer	Set the layer from which fields are displayed.
updateModel	Called when the model must be updated.

Static Methods

fieldToolTip	Returns a HTML formatted tooltip string for a field, containing details like the field name, alias and type.
fieldToolTipExtended	Returns a HTML formatted tooltip string for a field, containing details like the field name, alias, type and expression.

class qgis.core.QgsFieldModel

Bases: QAbstractItemModel

__init__(parent: QObject | None = None)

Constructor for QgsFieldModel - creates a model to display the fields of a given layer.

Parameters:

parent (Optional[QObject] = None)

class CustomRole(*values)

Bases: IntEnum

Custom model roles.

Note

Prior to QGIS 3.36 this was available as QgsFieldModel.FieldRoles

Added in version 3.36.

• FieldName: Return field name if index corresponds to a field

  Available as QgsFieldModel.FieldNameRole in older QGIS releases.

• FieldIndex: Return field index if index corresponds to a field

  Available as QgsFieldModel.FieldIndexRole in older QGIS releases.

• Expression: Return field name or expression

  Available as QgsFieldModel.ExpressionRole in older QGIS releases.

• IsExpression: Return if index corresponds to an expression

  Available as QgsFieldModel.IsExpressionRole in older QGIS releases.

• ExpressionValidity: Return if expression is valid or not

  Available as QgsFieldModel.ExpressionValidityRole in older QGIS releases.

• FieldType: Return the field type (if a field, return QVariant if expression)

  Available as QgsFieldModel.FieldTypeRole in older QGIS releases.

• FieldOrigin: Return the field origin (if a field, returns QVariant if expression)

  Available as QgsFieldModel.FieldOriginRole in older QGIS releases.

• IsEmpty: Return if the index corresponds to the empty value

  Available as QgsFieldModel.IsEmptyRole in older QGIS releases.

• EditorWidgetType: Editor widget type

• JoinedFieldIsEditable: True if a joined field is editable (returns QVariant if not a joined field)

• FieldIsWidgetEditable: True if a is editable from the widget

FieldRoles

alias of CustomRole

allowEmptyFieldName(self) → bool

Returns True if the model allows the empty field (“not set”) choice.

See also

setAllowEmptyFieldName()

Return type:

bool

allowExpression(self) → bool

Returns True if the model allows custom expressions to be created and displayed.

See also

setAllowExpression()

Return type:

bool

static fieldToolTip(field: QgsField) → str

Returns a HTML formatted tooltip string for a field, containing details like the field name, alias and type.

Parameters:

field (QgsField)

Return type:

str

static fieldToolTipExtended(field: QgsField, layer: QgsVectorLayer | None) → str

Returns a HTML formatted tooltip string for a field, containing details like the field name, alias, type and expression.

Added in version 3.14.

Parameters:

• field (QgsField)

• layer (Optional[QgsVectorLayer])

Return type:

str

fields(self) → QgsFields

Returns the fields currently shown in the model.

This will either be fields from the associated layer() or the fields manually set by a call to setFields().

Added in version 3.14.

Return type:

QgsFields

indexFromName(self, fieldName: str | None) → QModelIndex

Returns the index corresponding to a given fieldName.

Parameters:

fieldName (Optional[str])

Return type:

QModelIndex

isField(self, expression: str | None) → bool

Returns True if a string represents a field reference, or False if it is an expression consisting of more than direct field reference.

Parameters:

expression (Optional[str])

Return type:

bool

layer(self) → QgsVectorLayer | None

Returns the layer associated with the model.

See also

setLayer()

Return type:

Optional[QgsVectorLayer]

removeExpression(self)

Removes any custom expression from the model.

See also

setExpression()

See also

allowExpression()

setAllowEmptyFieldName(self, allowEmpty: bool)

Sets whether an optional empty field (“not set”) option is present in the model.

See also

allowEmptyFieldName()

Parameters:

allowEmpty (bool)

setAllowExpression(self, allowExpression: bool)

Sets whether custom expressions are accepted and displayed in the model.

See also

allowExpression()

See also

setExpression()

Parameters:

allowExpression (bool)

setExpression(self, expression: str | None)

Sets a single expression to be added after the fields at the end of the model.

See also

setAllowExpression()

See also

allowExpression()

See also

removeExpression()

Parameters:

expression (Optional[str])

setFields(self, fields: QgsFields)

Manually sets the fields to use for the model.

This method should only be used when the model ISN’T associated with a layer() and needs to show the fields from an arbitrary field collection instead. Calling setFields() will automatically clear any existing layer().

See also

fields()

Added in version 3.14.

Parameters:

fields (QgsFields)

setLayer(self, layer: QgsVectorLayer | None)

Set the layer from which fields are displayed.

See also

layer()

Parameters:

layer (Optional[QgsVectorLayer])

updateModel(self)

Called when the model must be updated.