[FEATURE][processing] Allow expression variables to be set for a model

This adds a new "Model Variables" dock panel to the model editor, allowing users to create and set custom expression variables for use in the model. These variables are available anywhere expressions are (correctly) evaluated within the model, so can be used as input parameter values for child algorithms, within data-defined dynamic parameters, etc. The use case here is for models which use a constant value throughout multiple steps within the model (e.g. @target_resolution: a target raster resolution, @max_simplification: a simplification value for input features coming from different sources, etc), allowing users one single place to define and edit these constant values (instead of hunting down and setting them in multiple places throughout the model). These variables are stored within the model itself, and are not exposed outside of the model designer dialog.
qgis · Feb 22, 2019 · c1aac32 · c1aac32
1 parent e31fb92
commit c1aac32
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Showing 3 changed files with 41 additions and 4 deletions.
diff --git a/python/plugins/processing/modeler/ModelerDialog.py b/python/plugins/processing/modeler/ModelerDialog.py
@@ -79,14 +79,17 @@
                        QgsProcessingUtils,
                        QgsProcessingModelAlgorithm,
                        QgsProcessingModelParameter,
-                       QgsProcessingParameterType
+                       QgsProcessingParameterType,
+                       QgsExpressionContextScope,
+                       QgsExpressionContext
                        )
 from qgis.gui import (QgsMessageBar,
                       QgsDockWidget,
                       QgsScrollArea,
                       QgsFilterLineEdit,
                       QgsProcessingToolboxTreeView,
-                      QgsProcessingToolboxProxyModel)
+                      QgsProcessingToolboxProxyModel,
+                      QgsVariableEditorWidget)
 from processing.gui.HelpEditionDialog import HelpEditionDialog
 from processing.gui.AlgorithmDialog import AlgorithmDialog
 from processing.modeler.ModelerParameterDefinitionDialog import ModelerParameterDefinitionDialog
@@ -140,6 +143,8 @@ def __init__(self, model=None):
 
         self.setupUi(self)
 
+        self._variables_scope = None
+
         # LOTS of bug reports when we include the dock creation in the UI file
         # see e.g. #16428, #19068
         # So just roll it all by hand......!
@@ -181,8 +186,7 @@ def __init__(self, model=None):
         self.scrollArea_1.setWidget(self.scrollAreaWidgetContents_1)
         self.verticalDockLayout_1.addWidget(self.scrollArea_1)
         self.propertiesDock.setWidget(propertiesDockContents)
-        self.addDockWidget(Qt.DockWidgetArea(1), self.propertiesDock)
-        self.propertiesDock.setWindowTitle(self.tr("Model properties"))
+        self.propertiesDock.setWindowTitle(self.tr("Model Properties"))
 
         self.inputsDock = QgsDockWidget(self)
         self.inputsDock.setFeatures(QDockWidget.DockWidgetFloatable | QDockWidget.DockWidgetMovable)
@@ -243,6 +247,22 @@ def __init__(self, model=None):
         self.searchBox.setToolTip(self.tr("Enter algorithm name to filter list"))
         self.searchBox.setShowSearchIcon(True)
 
+        self.variables_dock = QgsDockWidget(self)
+        self.variables_dock.setFeatures(QDockWidget.DockWidgetFloatable | QDockWidget.DockWidgetMovable)
+        self.variables_dock.setObjectName("variablesDock")
+        self.variables_dock_contents = QWidget()
+        vl_v = QVBoxLayout(self.algorithmsDockContents)
+        vl_v.setContentsMargins(0, 0, 0, 0)
+        self.variables_editor = QgsVariableEditorWidget()
+        vl_v.addWidget(self.variables_editor)
+        self.variables_dock_contents.setLayout(vl_v)
+        self.variables_dock.setWidget(self.variables_dock_contents)
+        self.addDockWidget(Qt.DockWidgetArea(1), self.variables_dock)
+        self.variables_dock.setWindowTitle(self.tr("Variables"))
+        self.addDockWidget(Qt.DockWidgetArea(1), self.propertiesDock)
+        self.tabifyDockWidget(self.propertiesDock, self.variables_dock)
+        self.variables_editor.scopeChanged.connect(self.variables_changed)
+
         self.bar = QgsMessageBar()
         self.bar.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Fixed)
         self.centralWidget().layout().insertWidget(0, self.bar)
@@ -455,6 +475,7 @@ def _mimeDataInput(items):
         else:
             self.model = QgsProcessingModelAlgorithm()
             self.model.setProvider(QgsApplication.processingRegistry().providerById('model'))
+        self.update_variables_gui()
 
         self.fillInputsTree()
 
@@ -492,6 +513,18 @@ def editHelp(self):
             self.model.setHelpContent(dlg.descriptions)
             self.hasChanged = True
 
+    def update_variables_gui(self):
+        variables_scope = QgsExpressionContextScope(self.tr('Model Variables'))
+        for k, v in self.model.variables().items():
+            variables_scope.setVariable(k, v)
+        variables_context = QgsExpressionContext()
+        variables_context.appendScope(variables_scope)
+        self.variables_editor.setContext(variables_context)
+        self.variables_editor.setEditableScopeIndex(0)
+
+    def variables_changed(self):
+        self.model.setVariables(self.variables_editor.variablesInActiveScope())
+
     def runModel(self):
         if len(self.model.childAlgorithms()) == 0:
             self.bar.pushMessage("", self.tr("Model doesn't contain any algorithm and/or parameter and can't be executed"), level=Qgis.Warning, duration=5)
@@ -722,6 +755,8 @@ def loadModel(self, filename):
             self.textName.setText(alg.name())
             self.repaintModel()
 
+            self.update_variables_gui()
+
             self.view.centerOn(0, 0)
             self.hasChanged = False
         else:

diff --git a/src/gui/processing/qgsprocessingmodelerparameterwidget.cpp b/src/gui/processing/qgsprocessingmodelerparameterwidget.cpp
@@ -198,6 +198,7 @@ QgsExpressionContext QgsProcessingModelerParameterWidget::createExpressionContex
     QStringList highlightedVariables = childScope->variableNames();
     QStringList highlightedFunctions = childScope->functionNames();
     highlightedVariables += algorithmScope->variableNames();
+    highlightedVariables += mModel->variables().keys();
     highlightedFunctions += algorithmScope->functionNames();
     c.setHighlightedVariables( highlightedVariables );
     c.setHighlightedFunctions( highlightedFunctions );

diff --git a/src/gui/processing/qgsprocessingwidgetwrapper.cpp b/src/gui/processing/qgsprocessingwidgetwrapper.cpp
@@ -326,6 +326,7 @@ QgsExpressionContext QgsProcessingGuiUtils::createExpressionContext( QgsProcessi
     QStringList highlightedVariables = childScope->variableNames();
     QStringList highlightedFunctions = childScope->functionNames();
     highlightedVariables += algorithmScope->variableNames();
+    highlightedVariables += widgetContext.model()->variables().keys();
     highlightedFunctions += algorithmScope->functionNames();
     c.setHighlightedVariables( highlightedVariables );
     c.setHighlightedFunctions( highlightedFunctions );