Class: QgsValueRelationFieldFormatter¶

class qgis.core.QgsValueRelationFieldFormatter¶

Bases: qgis._core.QgsFieldFormatter

Constructor for QgsValueRelationFieldFormatter.

QgsValueRelationFieldFormatter(QgsValueRelationFieldFormatter)

Field formatter for a value relation field. A value relation field formatter looks up the values from features on another layer.

New in version 3.0: Enums

Methods

`createCache`	createCache(config: Dict[str, Any], formFeature: QgsFeature = QgsFeature()) -> List[QgsValueRelationFieldFormatter.ValueRelationItem] Create a cache for a value relation field.
`expressionFormAttributes`	Returns a list of attributes required by the form context `expression`
`expressionFormVariables`	Returns a list of variables required by the form context `expression`
`expressionIsUsable`	Check whether the `feature` has all values required by the `expression`
`expressionRequiresFormScope`	Check if the `expression` requires a form scope (i.e.
`id`
`representValue`
`resolveLayer`	Returns the (possibly NULL) layer from the widget’s `config` and `project`
`sortValue`
`valueToStringList`	Utility to convert a list or a string representation of an (hstore style: {1,2…}) list in `value` to a string list

Signals

Attributes

class ValueRelationItem(key: Any, value: str)¶

Bases: sip.wrapper

Constructor for ValueRelationItem

QgsValueRelationFieldFormatter.ValueRelationItem() Constructor for ValueRelationItem

QgsValueRelationFieldFormatter.ValueRelationItem(QgsValueRelationFieldFormatter.ValueRelationItem)

key¶

value¶

createCache(self, layer: QgsVectorLayer, fieldIndex: int, config: Dict[str, Any]) → Any¶

createCache(config: Dict[str, Any], formFeature: QgsFeature = QgsFeature()) -> List[QgsValueRelationFieldFormatter.ValueRelationItem] Create a cache for a value relation field. This can be used to keep the value map in the local memory if doing multiple lookups in a loop.

Parameters

config – The widget configuration
formFeature – The feature currently being edited with current attribute values

Returns

A kvp list of values for the widget

New in version 3.0.

expressionFormAttributes(expression: str) → Set[str]¶

Returns a list of attributes required by the form context expression

Parameters: expression – Form filter expression
Returns: list of attributes required by the expression

New in version 3.2.

expressionFormVariables(expression: str) → Set[str]¶

Returns a list of variables required by the form context expression

Parameters: expression – Form filter expression
Returns: list of variables required by the expression

New in version 3.2.

expressionIsUsable(expression: str, feature: QgsFeature) → bool¶

Check whether the feature has all values required by the expression

Returns: True if the expression can be used

New in version 3.2.

expressionRequiresFormScope(expression: str) → bool¶

Check if the expression requires a form scope (i.e. if it uses fields or geometry of the currently edited feature).

Parameters: expression – The widget’s filter expression
Returns: True if the expression requires a form scope

New in version 3.2.

id(self) → str¶

representValue(self, layer: QgsVectorLayer, fieldIndex: int, config: Dict[str, Any], cache: Any, value: Any) → str¶

resolveLayer(config: Dict[str, Any], project: QgsProject) → QgsVectorLayer¶: Returns the (possibly NULL) layer from the widget’s config and project

New in version 3.8.

sortValue(self, layer: QgsVectorLayer, fieldIndex: int, config: Dict[str, Any], cache: Any, value: Any) → Any¶

valueToStringList(value: Any) → List[str]¶: Utility to convert a list or a string representation of an (hstore style: {1,2…}) list in value to a string list

New in version 3.2.