Class: QgsValueRelationFieldFormatter

class qgis.core.QgsValueRelationFieldFormatter

Bases: QgsFieldFormatter

Field formatter for a value relation field.

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

QgsValueRelationFieldFormatter() Constructor for QgsValueRelationFieldFormatter.

QgsValueRelationFieldFormatter(QgsValueRelationFieldFormatter)

Methods

availableValues

param config:

createCache

createCache(config: Dict[str, Any], formFeature: QgsFeature = QgsFeature(), parentFormFeature: 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, optionally checks for parentFeature

expressionParentFormAttributes

Returns a list of attributes required by the parent form's form context expression

expressionParentFormVariables

Returns a list of variables required by the parent form's form context expression

expressionRequiresFormScope

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

expressionRequiresParentFormScope

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

id

rtype:

str

representValue

param layer:

resolveLayer

Returns the (possibly NULL) layer from the widget's config and project

sortValue

param layer:

valueToStringList

Utility to convert a list or a string representation of an (hstore style: {1,2...}) list in value to a string list

class ValueRelationItem(key: Any, value: str, description: str = '', group: Any = None)

Bases: sip.wrapper

Constructor for ValueRelationItem

QgsValueRelationFieldFormatter.ValueRelationItem() Constructor for ValueRelationItem

QgsValueRelationFieldFormatter.ValueRelationItem(QgsValueRelationFieldFormatter.ValueRelationItem)

description
group
key
value
availableValues(self, config: Dict[str, Any], countLimit: int, context: QgsFieldFormatterContext) List[Any]
Parameters:
Return type:

List[Any]

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

createCache(config: Dict[str, Any], formFeature: QgsFeature = QgsFeature(), parentFormFeature: 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 (Dict[str) – The widget configuration

  • formFeature – The feature currently being edited with current attribute values

  • parentFormFeature – For embedded forms only, the feature currently being edited in the parent form with current attribute values

  • layer (QgsVectorLayer) –

  • fieldIndex (int) –

Return type:

Any

Returns:

A kvp list of values for the widget

expressionFormAttributes(expression: str) Set[str]

Returns a list of attributes required by the form context expression

Parameters:

expression (str) – Form filter expression

Return type:

Set[str]

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 (str) – Form filter expression

Return type:

Set[str]

Returns:

list of variables required by the expression

New in version 3.2.

expressionIsUsable(expression: str, feature: QgsFeature, parentFeature: QgsFeature = QgsFeature()) bool

Check whether the feature has all values required by the expression, optionally checks for parentFeature

Return type:

bool

Returns:

True if the expression can be used

New in version 3.2.

Parameters:
expressionParentFormAttributes(expression: str) Set[str]

Returns a list of attributes required by the parent form’s form context expression

Parameters:

expression (str) – Form filter expression

Return type:

Set[str]

Returns:

list of parent attributes required by the expression

New in version 3.14.

expressionParentFormVariables(expression: str) Set[str]

Returns a list of variables required by the parent form’s form context expression

Parameters:

expression (str) – Form filter expression

Return type:

Set[str]

Returns:

list of parent variables required by the expression

New in version 3.14.

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 (str) – The widget’s filter expression

Return type:

bool

Returns:

True if the expression requires a form scope

New in version 3.2.

expressionRequiresParentFormScope(expression: str) bool

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

Parameters:

expression (str) – The widget’s filter expression

Return type:

bool

Returns:

True if the expression requires a parent form scope

New in version 3.14.

id(self) str
Return type:

str

representValue(self, layer: QgsVectorLayer, fieldIndex: int, config: Dict[str, Any], cache: Any, value: Any) str
Parameters:
  • layer (QgsVectorLayer) –

  • fieldIndex (int) –

  • config (Dict[str) –

  • cache (Any) –

  • value (Any) –

Return type:

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.

Parameters:
Return type:

QgsVectorLayer

sortValue(self, layer: QgsVectorLayer, fieldIndex: int, config: Dict[str, Any], cache: Any, value: Any) Any
Parameters:
  • layer (QgsVectorLayer) –

  • fieldIndex (int) –

  • config (Dict[str) –

  • cache (Any) –

  • value (Any) –

Return type:

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.

Parameters:

value (Any) –

Return type:

List[str]