Class: QgsAbstractPropertyCollection¶
-
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.
- Parameters
name –
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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, orFalse
if all properties within the collection are deactivated.See also
- Return type
bool
-
hasDynamicProperties
(self) → bool¶ Returns
True
if the collection has any active, non-static properties, orFalse
if either all non-static properties within the collection are deactivated or if the collection only contains static properties.See also
- Return type
bool
-
hasProperty
(self, key: int) → bool¶ Returns
True
if the collection contains a property with the specified key.- Parameters
key (int) – integer key for property. The intended use case is that a context specific enum is cast to int and used for the key value.
See also
- Return type
bool
-
isActive
(self, key: int) → bool¶ Returns
True
if the collection contains an active property with the specified key.- Parameters
key (int) – 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.
- Return type
bool
-
loadVariant
(self, configuration: Any, definitions: Dict[int, QgsPropertyDefinition]) → bool¶ Loads this property collection from a QVariantMap, wrapped in a QVariant. You can use QgsXmlUtils.readVariant to save it to an XML document.
See also
- Parameters
configuration (Any) –
definitions (Dict[int) –
- Return type
bool
-
name
(self) → str¶ Returns the descriptive name of the property collection.
See also
- Return type
str
-
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.- Parameters
context (
QgsExpressionContext
= QgsExpressionContext()) –- Return type
bool
-
property
(self, key: int) → QgsProperty¶ Returns a matching property from the collection, if one exists.
- Parameters
key (int) – 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.
- Return type
- Returns
matching property, or null if no matching, active property found.
See also
-
propertyKeys
(self) → object¶ Returns a list of property keys contained within the collection.
- Return type
object
-
readXml
(self, collectionElem: QDomElement, definitions: Dict[int, QgsPropertyDefinition]) → bool¶ Reads property collection state from an XML element.
- Parameters
collectionElem (QDomElement) – source DOM element for property collection’s state
definitions (Dict[int) – property definitions
See also
- Return type
bool
-
referencedFields
(self, context: QgsExpressionContext = QgsExpressionContext()) → Set[str]¶ Returns the set of any fields referenced by the active properties from the collection.
- Parameters
context (
QgsExpressionContext
= QgsExpressionContext()) – expression context the properties will be evaluated against.- Return type
Set[str]
-
setName
(self, name: str)¶ Sets the descriptive name for the property collection.
See also
- Parameters
name (str) –
-
toVariant
(self, definitions: Dict[int, QgsPropertyDefinition]) → Any¶ Saves this property collection to a QVariantMap, wrapped in a QVariant. You can use QgsXmlUtils.writeVariant to save it to an XML document.
See also
- Parameters
definitions (Dict[int) –
- Return type
Any
-
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. If you need the validity of the value (like ok provided from the valueAs* variants) refer to the property() and
QgsProperty.value()
- Parameters
key (int) – 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) – expression context to evaluate property against
defaultValue (Any = None) – default value to return if no matching, active property found or if the property value cannot be calculated
- Return type
Any
- Returns
calculated property value, or default value if property could not be evaluated
See also
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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 (int) – 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) –
QgsExpressionContext
to evaluate the property for.defaultValue (bool = False) – default boolean to return if the property cannot be calculated as a boolean
- Return type
Tuple[bool, bool]
- Returns
value parsed to bool
ok: will be set to
True
if conversion was successful
See also
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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 (int) – 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) –
QgsExpressionContext
to evaluate the property for.defaultColor (Union[QColor) – default color to return if the property cannot be calculated as a color
- Return type
Tuple[QColor, bool]
- 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 (int) – 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) –
QgsExpressionContext
to evaluate the property for.defaultValue (float = 0) – default double to return if the property cannot be calculated as a double
- Return type
Tuple[float, bool]
- Returns
value parsed to double
ok: will be set to
True
if conversion was successful
See also
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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 (int) – 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) –
QgsExpressionContext
to evaluate the property for.defaultValue (int = 0) – default integer to return if the property cannot be calculated as a integer
- Return type
Tuple[int, bool]
- 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 (int) – 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) –
QgsExpressionContext
to evaluate the property for.defaultString (str = '') – default string to return if the property cannot be calculated as a string
- Return type
Tuple[str, bool]
- Returns
value parsed to string
ok: will be set to
True
if conversion was successful
See also
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-
writeXml
(self, collectionElem: QDomElement, definitions: Dict[int, QgsPropertyDefinition]) → bool¶ Writes the current state of the property collection into an XML element
- Parameters
collectionElem (QDomElement) – destination element for the property collection’s state
definitions (Dict[int) – property definitions
See also
- Return type
bool