Run QgsProcessingAlgorithm with explicitely defined QgsProcessingContext and QgisInterfaces.

python/plugins/processing/ProcessingPlugin.py

@@ -21,13 +21,11 @@
 
 import shutil
 import os
-import sys
-from typing import List
+from typing import Optional
 from functools import partial
 
 from qgis.core import (
     QgsApplication,
-    QgsProcessingUtils,
     QgsProcessingModelAlgorithm,
     QgsProcessingAlgorithm,
     QgsDataItemProvider,
@@ -36,25 +34,26 @@
     QgsMapLayerType,
     QgsMimeDataUtils,
     QgsSettings,
+    QgsProcessingContext,
 )
 from qgis.gui import (
     QgsGui,
     QgsOptionsWidgetFactory,
     QgsCustomDropHandler,
     QgsProcessingHistoryDialog,
+    QgisInterface,
 )
 from qgis.PyQt.QtCore import (
     QObject,
     Qt,
-    QItemSelectionModel,
     QCoreApplication,
     QDir,
     QFileInfo,
     pyqtSlot,
     QMetaObject,
 )
 from qgis.PyQt.QtWidgets import QWidget, QMenu, QAction
-from qgis.PyQt.QtGui import QIcon, QKeySequence
+from qgis.PyQt.QtGui import QKeySequence
 from qgis.utils import iface
 
 from processing.core.Processing import Processing
@@ -82,7 +81,6 @@
     createButtons,
     removeButtons,
 )
-from processing.core.ProcessingResults import resultsList
 
 pluginPath = os.path.dirname(__file__)
 
@@ -421,7 +419,15 @@ def updateProjectModelMenu(self):
                 )
 
     @pyqtSlot(str, QWidget, bool, bool)
-    def executeAlgorithm(self, alg_id, parent, in_place=False, as_batch=False):
+    def executeAlgorithm(
+        self,
+        alg_id,
+        parent,
+        in_place=False,
+        as_batch=False,
+        context: Optional[QgsProcessingContext] = None,
+        iface: Optional[QgisInterface] = None,
+    ):
         """Executes a project model with GUI interaction if needed.
 
         :param alg_id: algorithm id
@@ -432,8 +438,16 @@ def executeAlgorithm(self, alg_id, parent, in_place=False, as_batch=False):
         :type in_place: bool, optional
         :param as_batch: execute as batch flag, defaults to False
         :type as_batch: bool, optional
+        :param context: alternative processing context, e.g. to allow users to select layers that are not
+                        available in QgsProject.instance()
+        :type context: QgsProcessingContext, optional
+        :param iface: alternative QgisInterface, defaults to standard QgisInterface (QGIS Main GUI)
+        :type iface: QgisInterface, optional
         """
 
+        if iface is None:
+            iface = self.iface
+
         config = {}
         if in_place:
             config["IN_PLACE"] = True
@@ -459,7 +473,9 @@ def executeAlgorithm(self, alg_id, parent, in_place=False, as_batch=False):
                 return
 
             if as_batch:
-                dlg = BatchAlgorithmDialog(alg, iface.mainWindow())
+                dlg = BatchAlgorithmDialog(
+                    alg, iface.mainWindow(), context=context, iface=iface
+                )
                 dlg.show()
                 dlg.exec()
             else:
@@ -473,8 +489,12 @@ def executeAlgorithm(self, alg_id, parent, in_place=False, as_batch=False):
                     if d.name() not in (in_place_input_parameter_name, "OUTPUT")
                 ]:
                     parameters = {}
-                    feedback = MessageBarProgress(algname=alg.displayName())
-                    ok, results = execute_in_place(alg, parameters, feedback=feedback)
+                    feedback = MessageBarProgress(
+                        algname=alg.displayName(), messagebar=iface.messageBar()
+                    )
+                    ok, results = execute_in_place(
+                        alg, parameters, context=context, feedback=feedback, iface=iface
+                    )
                     if ok:
                         iface.messageBar().pushSuccess(
                             "",
@@ -491,7 +511,10 @@ def executeAlgorithm(self, alg_id, parent, in_place=False, as_batch=False):
                     dlg = alg.createCustomParametersWidget(parent)
 
                     if not dlg:
-                        dlg = AlgorithmDialog(alg, in_place, iface.mainWindow())
+                        dlg = AlgorithmDialog(
+                            alg, in_place, context=context, iface=iface
+                        )
+
                     canvas = iface.mapCanvas()
                     prevMapTool = canvas.mapTool()
                     dlg.show()
@@ -507,10 +530,10 @@ def executeAlgorithm(self, alg_id, parent, in_place=False, as_batch=False):
                             pass
                 else:
                     feedback = MessageBarProgress(algname=alg.displayName())
-                    context = dataobjects.createContext(feedback)
+                    context = dataobjects.createContext(feedback, context=context)
                     parameters = {}
                     ret, results = execute(alg, parameters, context, feedback)
-                    handleAlgorithmResults(alg, context, feedback)
+                    handleAlgorithmResults(alg, context, feedback, iface=iface)
                     feedback.close()
 
     def sync_in_place_button_state(self, layer=None):

python/plugins/processing/gui/AlgorithmDialog.py

@@ -21,13 +21,15 @@
 
 import datetime
 import time
+from typing import Optional
 
 from qgis.PyQt.QtCore import QCoreApplication
 from qgis.PyQt.QtWidgets import QMessageBox, QPushButton, QDialogButtonBox
 from qgis.PyQt.QtGui import QColor, QPalette
 
 from qgis.core import (
     Qgis,
+    QgsProcessingContext,
     QgsApplication,
     QgsProcessingAlgRunnerTask,
     QgsProcessingOutputHtml,
@@ -37,9 +39,9 @@
 )
 from qgis.gui import (
     QgsGui,
+    QgisInterface,
     QgsProcessingAlgorithmDialogBase,
     QgsProcessingParametersGenerator,
-    QgsProcessingContextGenerator,
 )
 from qgis.utils import iface
 
@@ -56,13 +58,21 @@
 
 class AlgorithmDialog(QgsProcessingAlgorithmDialogBase):
 
-    def __init__(self, alg, in_place=False, parent=None):
+    def __init__(
+        self,
+        alg,
+        in_place=False,
+        parent=None,
+        context: Optional[QgsProcessingContext] = None,
+        iface: Optional[QgisInterface] = iface,
+    ):
         super().__init__(parent)
 
         self.feedback_dialog = None
         self.in_place = in_place
         self.active_layer = iface.activeLayer() if self.in_place else None
 
+        self.parent_context = context
         self.context = None
         self.feedback = None
         self.history_log_id = None
@@ -106,7 +116,9 @@ def __init__(self, alg, in_place=False, parent=None):
         self.updateRunButtonVisibility()
 
     def getParametersPanel(self, alg, parent):
-        panel = ParametersPanel(parent, alg, self.in_place, self.active_layer)
+        panel = ParametersPanel(
+            parent, alg, self.in_place, self.active_layer, context=self.parent_context
+        )
         return panel
 
     def runAsBatch(self):
@@ -178,14 +190,18 @@ def createProcessingParameters(
     def processingContext(self):
         if self.context is None:
             self.feedback = self.createFeedback()
-            self.context = dataobjects.createContext(self.feedback)
+            self.context = dataobjects.createContext(
+                self.feedback, context=self.parent_context
+            )
 
         self.applyContextOverrides(self.context)
         return self.context
 
     def runAlgorithm(self):
         self.feedback = self.createFeedback()
-        self.context = dataobjects.createContext(self.feedback)
+        self.context = dataobjects.createContext(
+            self.feedback, context=self.parent_context
+        )
         self.applyContextOverrides(self.context)
         self.algorithmAboutToRun.emit(self.context)
 

python/plugins/processing/gui/AlgorithmExecutor.py

@@ -20,10 +20,10 @@
 __copyright__ = "(C) 2012, Victor Olaya"
 
 import sys
+from typing import Optional
 from qgis.PyQt.QtCore import QCoreApplication
 from qgis.core import (
     Qgis,
-    QgsApplication,
     QgsFeatureSink,
     QgsProcessingFeedback,
     QgsProcessingUtils,
@@ -32,18 +32,16 @@
     QgsProcessingFeatureSourceDefinition,
     QgsProcessingFeatureSource,
     QgsProcessingParameters,
-    QgsProject,
     QgsFeatureRequest,
     QgsFeature,
     QgsExpression,
-    QgsWkbTypes,
-    QgsGeometry,
     QgsVectorLayerUtils,
     QgsVectorLayer,
 )
 from processing.gui.Postprocessing import handleAlgorithmResults
 from processing.tools import dataobjects
-from qgis.utils import iface
+from qgis.gui import QgisInterface
+from qgis.utils import iface as qgis_iface
 
 
 def execute(alg, parameters, context=None, feedback=None, catch_exceptions=True):
@@ -364,7 +362,9 @@ def execute_in_place_run(
     return False, {}
 
 
-def execute_in_place(alg, parameters, context=None, feedback=None):
+def execute_in_place(
+    alg, parameters, context=None, feedback=None, iface: Optional[QgisInterface] = None
+):
     """Executes an algorithm modifying features in-place, if the INPUT
     parameter is not defined, the current active layer will be used as
     INPUT.
@@ -377,11 +377,14 @@ def execute_in_place(alg, parameters, context=None, feedback=None):
     :param context: QgsProcessingContext, optional
     :param feedback: feedback, defaults to None
     :param feedback: QgsProcessingFeedback, optional
+    :param iface: QgisInterface, options, defaults to standard QgisInterface (from qgis.utils import iface)
     :raises QgsProcessingException: raised when the layer is not editable or the layer cannot be found in the current project
     :return: a tuple with true if success and results
     :rtype: tuple
     """
 
+    if iface is None:
+        iface = qgis_iface
     if feedback is None:
         feedback = QgsProcessingFeedback()
     if context is None:
@@ -423,12 +426,21 @@ def execute_in_place(alg, parameters, context=None, feedback=None):
     return ok, results
 
 
-def executeIterating(alg, parameters, paramToIter, context, feedback):
+def executeIterating(
+    alg,
+    parameters,
+    paramToIter,
+    context,
+    feedback,
+    iface: Optional[QgisInterface] = None,
+):
     # Generate all single-feature layers
     parameter_definition = alg.parameterDefinition(paramToIter)
     if not parameter_definition:
         return False
 
+    if iface is None:
+        iface = qgis_iface
     iter_source = QgsProcessingParameters.parameterAsSource(
         parameter_definition, parameters, context
     )
@@ -487,7 +499,7 @@ def executeIterating(alg, parameters, paramToIter, context, feedback):
         if not ret:
             return False
 
-    handleAlgorithmResults(alg, context, feedback)
+    handleAlgorithmResults(alg, context, feedback, iface=iface)
     return True