Class: QgsPropertyCollectionStack

class qgis.core.QgsPropertyCollectionStack

Bases: qgis._core.QgsAbstractPropertyCollection

Constructor for QgsPropertyCollectionStack.

QgsPropertyCollectionStack(other: QgsPropertyCollectionStack) Copy constructor

An ordered stack of QgsPropertyCollection containers, where collections added later to the stack will take priority over earlier collections.

New in version 3.0: Methods

appendCollection Appends a collection to the end of the stack, and transfers ownership of the collection to the stack.
at Returns the collection at the corresponding index from the stack.
clear Removes all collections from the stack.
collection Returns the first collection with a matching name from the stack.
count Returns the number of collections contained within the stack.
hasActiveProperties Returns true if the collection has any active properties, or false if all properties within the collection are deactivated.
hasDynamicProperties Returns true if the collection has any active, non-static properties, or false if either all non-static properties within the collection are deactivated or if the collection only contains static properties.
hasProperty
isActive Returns true if the stack contains an active property with the specified key.
loadVariant
prepare
property Returns the highest priority property with a matching key from within the stack.
propertyKeys
referencedFields Returns the set of any fields referenced by the active properties from the stack.
toVariant
value Returns the calculated value of the highest priority property with the specified key from within the stack.

Signals

Attributes

appendCollection(self, collection: QgsPropertyCollection)

Appends a collection to the end of the stack, and transfers ownership of the collection to the stack. Properties from the newly added collection will take priority over any existing properties with the same name.

Parameters:collection – collection to append. Ownership is transferred to the stack.
at(self, index: int) → QgsPropertyCollection

Returns the collection at the corresponding index from the stack.

Parameters:index – position of collection, 0 based
Returns:collection if one exists at the specified index
clear(self)

Removes all collections from the stack.

collection(self, name: str) → QgsPropertyCollection

Returns the first collection with a matching name from the stack.

Parameters:name – name of collection to find
Returns:collection if one exists with the specified name
count(self) → int

Returns the number of collections contained within the stack.

hasActiveProperties(self) → bool

Returns true if the collection has any active properties, or false if all properties within the collection are deactivated.

See also

isActive()

hasDynamicProperties(self) → bool

Returns true if the collection has any active, non-static properties, or false if either all non-static properties within the collection are deactivated or if the collection only contains static properties.

hasProperty(self, key: int) → bool
isActive(self, key: int) → bool

Returns true if the stack contains an active property with the specified key.

Parameters:key – integer key for property to test. The intended use case is that a context specific enum is cast to int and used for the key value.
loadVariant(self, collection: Any, definitions: object) → bool
prepare(self, context: QgsExpressionContext = QgsExpressionContext()) → bool
property(self, key: int) → QgsProperty

Returns the highest priority property with a matching key from within the stack.

Parameters:key – integer key for property to return. The intended use case is that a context specific enum is cast to int and used for the key value.
Returns:matching property, or null if no matching, active property found.

See also

hasActiveProperty()

propertyKeys(self) → object
referencedFields(self, context: QgsExpressionContext = QgsExpressionContext()) → Set[str]

Returns the set of any fields referenced by the active properties from the stack.

Parameters:context – expression context the properties will be evaluated against.
toVariant(self, definitions: object) → Any
value(self, key: int, context: QgsExpressionContext, defaultValue: Any = None) → Any

Returns the calculated value of the highest priority property with the specified key from within the stack.

Parameters:
  • key – integer key for property to calculate. The intended use case is that a context specific enum is cast to int and used for the key value.
  • context – expression context to evaluate property against
  • defaultValue – default value to return if no matching, active property found or if the property value cannot be calculated
Returns:

calculated property value, or default value if property could not be evaluated