Class: QgsAbstractPropertyCollection¶
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class
qgis.core.
QgsAbstractPropertyCollection
(name: str = '')¶ Bases:
sip.wrapper
Constructor for QgsAbstractPropertyCollection. The name parameter should be set to a descriptive name for the collection.
QgsAbstractPropertyCollection(QgsAbstractPropertyCollection)
Abstract base class for QgsPropertyCollection like objects.
New in version 3.0: Enums
Methods
Removes all properties from the collection.
Returns true if the collection has any active properties, or false if all properties within the collection are deactivated.
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.
Returns true if the collection contains a property with the specified key.
Returns true if the collection contains an active property with the specified key.
Loads this property collection from a QVariantMap, wrapped in a QVariant.
Returns the descriptive name of the property collection.
Prepares the collection against a specified expression context.
Returns a matching property from the collection, if one exists.
Returns a list of property keys contained within the collection.
Reads property collection state from an XML element.
Returns the set of any fields referenced by the active properties from the collection.
Sets the descriptive name for the property collection.
Saves this property collection to a QVariantMap, wrapped in a QVariant.
Returns the calculated value of the property with the specified key from within the collection.
Calculates the current value of the property with the specified key and interprets it as an boolean.
Calculates the current value of the property with the specified key and interprets it as a color.
Calculates the current value of the property with the specified key and interprets it as a double.
Calculates the current value of the property with the specified key and interprets it as an integer.
Calculates the current value of the property with the specified key and interprets it as a string.
Writes the current state of the property collection into an XML element
Signals
Attributes
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clear
(self)¶ Removes all properties from the collection.
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hasActiveProperties
(self) → bool¶ Returns true if the collection has any active properties, or false if all properties within the collection are deactivated.
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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.
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hasProperty
(self, key: int) → bool¶ Returns true if the collection contains a property with the specified key.
- Parameters
key – integer key for property. The intended use case is that a context specific enum is cast to int and used for the key value.
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isActive
(self, key: int) → bool¶ Returns true if the collection 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.
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loadVariant
(self, configuration: Any, definitions: object) → bool¶ Loads this property collection from a QVariantMap, wrapped in a QVariant. You can use QgsXmlUtils.readVariant to save it to an XML document.
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prepare
(self, context: QgsExpressionContext = QgsExpressionContext()) → bool¶ Prepares the collection against a specified expression context. Calling prepare before evaluating the collection’s properties multiple times allows precalculation of expensive setup tasks such as parsing expressions. Returns true if preparation was successful.
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property
(self, key: int) → QgsProperty¶ Returns a matching property from the collection, if one exists.
- 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.
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propertyKeys
(self) → object¶ Returns a list of property keys contained within the collection.
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readXml
(self, collectionElem: QDomElement, definitions: object) → bool¶ Reads property collection state from an XML element.
- Parameters
collectionElem – source DOM element for property collection’s state
definitions – property definitions
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referencedFields
(self, context: QgsExpressionContext = QgsExpressionContext()) → Set[str]¶ Returns the set of any fields referenced by the active properties from the collection.
- Parameters
context – expression context the properties will be evaluated against.
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toVariant
(self, definitions: object) → Any¶ Saves this property collection to a QVariantMap, wrapped in a QVariant. You can use QgsXmlUtils.writeVariant to save it to an XML document.
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value
(self, key: int, context: QgsExpressionContext, defaultValue: Any = None) → Any¶ Returns the calculated value of the property with the specified key from within the collection.
- 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.
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
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valueAsBool
(self, key: int, context: QgsExpressionContext, defaultValue: bool = False) → Tuple[bool, bool]¶ Calculates the current value of the property with the specified key and interprets it as an boolean.
- 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.
context – QgsExpressionContext to evaluate the property for.
defaultValue – default boolean to return if the property cannot be calculated as a boolean
- Returns
value parsed to bool
ok: will be set to true if conversion was successful
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valueAsColor
(self, key: int, context: QgsExpressionContext, defaultColor: Union[QColor, Qt.GlobalColor, QGradient] = QColor()) → Tuple[QColor, bool]¶ Calculates the current value of the property with the specified key and interprets it as a color.
- 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.
context – QgsExpressionContext to evaluate the property for.
defaultColor – default color to return if the property cannot be calculated as a color
- Returns
value parsed to color
ok: will be set to true if conversion was successful
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valueAsDouble
(self, key: int, context: QgsExpressionContext, defaultValue: float = 0) → Tuple[float, bool]¶ Calculates the current value of the property with the specified key and interprets it as a double.
- 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.
context – QgsExpressionContext to evaluate the property for.
defaultValue – default double to return if the property cannot be calculated as a double
- Returns
value parsed to double
ok: will be set to true if conversion was successful
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valueAsInt
(self, key: int, context: QgsExpressionContext, defaultValue: int = 0) → Tuple[int, bool]¶ Calculates the current value of the property with the specified key and interprets it as an integer.
- 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.
context – QgsExpressionContext to evaluate the property for.
defaultValue – default integer to return if the property cannot be calculated as a integer
- Returns
value parsed to integer
ok: will be set to true if conversion was successful
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valueAsString
(self, key: int, context: QgsExpressionContext, defaultString: str = '') → Tuple[str, bool]¶ Calculates the current value of the property with the specified key and interprets it as a string.
- 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.
context – QgsExpressionContext to evaluate the property for.
defaultString – default string to return if the property cannot be calculated as a string
- Returns
value parsed to string
ok: will be set to true if conversion was successful
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