Subgroup: Processing
Class: QgsProcessingContext¶
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class
qgis.core.
QgsProcessingContext
¶ Bases:
sip.wrapper
Constructor for QgsProcessingContext.
Contains information about the context in which a processing algorithm is executed.
Contextual information includes settings such as the associated project, and expression context.
New in version 3.0: Methods
addLayerToLoadOnCompletion
Adds a layer
to load (by ID or datasource) into the canvas upon completion of the algorithm or model.copyThreadSafeSettings
Copies all settings which are safe for use across different threads from other
to this context.defaultEncoding
Returns the default encoding to use for newly created files. expressionContext
Returns the expression context. feedback
Returns the associated feedback object. flags
Returns any flags set in the context. getMapLayer
Returns a map layer from the context with a matching identifier
.invalidGeometryCheck
Returns the behavior used for checking invalid geometries in input layers. layersToLoadOnCompletion
Returns a map of layers (by ID or datasource) to LayerDetails, to load into the canvas upon completion of the algorithm or model. project
Returns the project in which the algorithm is being executed. pushToThread
Pushes the thread affinity for the context (including all layers contained in the temporaryLayerStore()) into another thread
.setDefaultEncoding
Sets the default encoding
to use for newly created files.setExpressionContext
Sets the expression context
.setFeedback
Sets an associated feedback
object.setFlags
Sets flags
for the context.setInvalidGeometryCallback
Sets a callback function to use when encountering an invalid geometry and invalidGeometryCheck() is set to GeometryAbortOnInvalid. setInvalidGeometryCheck
Sets the behavior used for checking invalid geometries in input layers. setLayersToLoadOnCompletion
Sets the map of layers
(by ID or datasource) to LayerDetails, to load into the canvas upon completion of the algorithm or model.setProject
Sets the project
in which the algorithm will be executed.setTransformContext
Sets the coordinate transform context
.setTransformErrorCallback
Sets a callback function to use when encountering a transform error when iterating features. takeResultLayer
Takes the result map layer with matching id
from the context and transfers ownership of it back to the caller.takeResultsFrom
Takes the results from another context
and merges them with the results currently stored in this context.temporaryLayerStore
Returns a reference to the layer store used for storing temporary layers during algorithm execution. thread
Returns the thread in which the context lives. transformContext
Returns the coordinate transform context. Signals
Attributes
-
class
Flag
¶ Bases:
int
-
class
Flags
¶ Bases:
sip.wrapper
QgsProcessingContext.Flags(Union[QgsProcessingContext.Flags, QgsProcessingContext.Flag]) QgsProcessingContext.Flags(QgsProcessingContext.Flags)
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class
LayerDetails
(name: str, project: QgsProject, outputName: str = '')¶ Bases:
sip.wrapper
Constructor for LayerDetails.
QgsProcessingContext.LayerDetails(QgsProcessingContext.LayerDetails)
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name
¶
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outputName
¶
-
project
¶
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addLayerToLoadOnCompletion
(self, layer: str, details: QgsProcessingContext.LayerDetails)¶ Adds a
layer
to load (by ID or datasource) into the canvas upon completion of the algorithm or model. Thedetails
parameter dictates the LayerDetails.See also
See also
-
copyThreadSafeSettings
(self, other: QgsProcessingContext)¶ Copies all settings which are safe for use across different threads from
other
to this context.
-
defaultEncoding
(self) → str¶ Returns the default encoding to use for newly created files.
See also
-
expressionContext
(self) → QgsExpressionContext¶ Returns the expression context.
-
feedback
(self) → QgsProcessingFeedback¶ Returns the associated feedback object.
See also
-
flags
(self) → QgsProcessingContext.Flags¶ Returns any flags set in the context.
See also
-
getMapLayer
(self, identifier: str) → QgsMapLayer¶ Returns a map layer from the context with a matching
identifier
. This method considers layer IDs, names and sources when matching theidentifier
(seeQgsProcessingUtils.mapLayerFromString()
for details).Ownership is not transferred and remains with the context.
See also
-
invalidGeometryCheck
(self) → QgsFeatureRequest.InvalidGeometryCheck¶ Returns the behavior used for checking invalid geometries in input layers.
See also
-
layersToLoadOnCompletion
(self) → object¶ Returns a map of layers (by ID or datasource) to LayerDetails, to load into the canvas upon completion of the algorithm or model.
See also
See also
-
project
(self) → QgsProject¶ Returns the project in which the algorithm is being executed.
See also
-
pushToThread
(self, thread: QThread)¶ Pushes the thread affinity for the context (including all layers contained in the temporaryLayerStore()) into another
thread
. This method is only safe to call when the current thread matches the existing thread affinity for the context (see thread()).See also
-
setDefaultEncoding
(self, encoding: str)¶ Sets the default
encoding
to use for newly created files.See also
-
setExpressionContext
(self, context: QgsExpressionContext)¶ Sets the expression
context
.
-
setFeedback
(self, feedback: QgsProcessingFeedback)¶ Sets an associated
feedback
object. This allows context related functions to report feedback and errors to users and processing logs. While ideally this feedback object should outlive the context, only a weak pointer tofeedback
is stored and no errors will occur if feedback is deleted before the context. Ownership offeedback
is not transferred.See also
-
setFlags
(self, flags: Union[QgsProcessingContext.Flags, QgsProcessingContext.Flag])¶ Sets
flags
for the context.See also
-
setInvalidGeometryCallback
(self, Callable[..., None])¶ Sets a callback function to use when encountering an invalid geometry and invalidGeometryCheck() is set to GeometryAbortOnInvalid. This function will be called using the feature with invalid geometry as a parameter.
New in version 3.0.
See also
invalidGeometryCallback()
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setInvalidGeometryCheck
(self, check: QgsFeatureRequest.InvalidGeometryCheck)¶ Sets the behavior used for checking invalid geometries in input layers. Settings this to anything but QgsFeatureRequest.GeometryNoCheck will also reset the invalidGeometryCallback() to a default implementation.
See also
-
setLayersToLoadOnCompletion
(self, layers: Dict[str, QgsProcessingContext.LayerDetails])¶ Sets the map of
layers
(by ID or datasource) to LayerDetails, to load into the canvas upon completion of the algorithm or model.See also
See also
-
setProject
(self, project: QgsProject)¶ Sets the
project
in which the algorithm will be executed.This also automatically sets the transformContext() to match the project’s transform context.
See also
-
setTransformContext
(self, context: QgsCoordinateTransformContext)¶ Sets the coordinate transform
context
.Note that setting a project for the context will automatically set the coordinate transform context.
See also
-
setTransformErrorCallback
(self, Callable[..., None])¶ Sets a callback function to use when encountering a transform error when iterating features. This function will be called using the feature which encountered the transform error as a parameter.
New in version 3.0.
See also
transformErrorCallback()
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takeResultLayer
(self, id: str) → QgsMapLayer¶ Takes the result map layer with matching
id
from the context and transfers ownership of it back to the caller. This method can be used to remove temporary layers which are not required for further processing from a context.See also
-
takeResultsFrom
(self, context: QgsProcessingContext)¶ Takes the results from another
context
and merges them with the results currently stored in this context. This includes settings like any layers loaded in the temporaryLayerStore() and layersToLoadOnCompletion(). This is only safe to call when both this context and the othercontext
share the same thread() affinity, and that thread is the current thread.
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temporaryLayerStore
(self) → QgsMapLayerStore¶ Returns a reference to the layer store used for storing temporary layers during algorithm execution.
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thread
(self) → QThread¶ Returns the thread in which the context lives.
See also
-
transformContext
(self) → QgsCoordinateTransformContext¶ Returns the coordinate transform context.
See also
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class