[processing] Ensure parameters linked to layer parameters

(e.g. field choices) are correctly updated when a layer
is selected which doesn't belong to the project

python/plugins/processing/gui/wrappers.py

@@ -901,6 +901,7 @@ def selectFile(self):
                 self.combo.setCurrentIndex(self.combo.findText(filename))
             else:
                 self.combo.setEditText(filename)
+            self.widgetValueHasChanged.emit(self)
 
     def setValue(self, value):
         if value is None or value == NULL:
@@ -918,6 +919,7 @@ def setValue(self, value):
             self.widget.setText(value)
         else:
             self.setComboValue(value, combobox=self.combo)
+        self.widgetValueHasChanged.emit(self)
 
     def value(self):
         if self.dialogType == DIALOG_STANDARD:
@@ -962,6 +964,7 @@ def selectFile(self):
                 self.combo.setCurrentIndex(self.combo.findText(filename))
             else:
                 self.combo.setEditText(filename)
+            self.widgetValueHasChanged.emit(self)
 
 
 class EnumWidgetWrapper(WidgetWrapper):
@@ -1136,6 +1139,7 @@ def selectFile(self):
                 self.combo.setCurrentIndex(self.combo.findText(filename))
             else:
                 self.combo.setEditText(filename)
+            self.widgetValueHasChanged.emit(self)
 
     def setValue(self, value):
         if value is None or value == NULL:
@@ -1153,6 +1157,7 @@ def setValue(self, value):
             self.widget.setValue(value)
         else:
             self.setComboValue(value, combobox=self.combo)
+        self.widgetValueHasChanged.emit(self)
 
     def value(self):
         if self.dialogType == DIALOG_STANDARD:
@@ -1280,6 +1285,10 @@ def validator(v):
 
 class ExpressionWidgetWrapper(WidgetWrapper):
 
+    def __init__(self, param, dialog, row=0, col=0, **kwargs):
+        super().__init__(param, dialog, row, col, **kwargs)
+        self.context = dataobjects.createContext()
+
     def createWidget(self):
         if self.dialogType in (DIALOG_STANDARD, DIALOG_BATCH):
             if self.param.parentLayerParameterName():
@@ -1312,11 +1321,10 @@ def parentLayerChanged(self, wrapper):
         self.setLayer(wrapper.value())
 
     def setLayer(self, layer):
-        context = dataobjects.createContext()
         if isinstance(layer, QgsProcessingFeatureSourceDefinition):
-            layer, ok = layer.source.valueAsString(context.expressionContext())
+            layer, ok = layer.source.valueAsString(self.context.expressionContext())
         if isinstance(layer, str):
-            layer = QgsProcessingUtils.mapLayerFromString(layer, context)
+            layer = QgsProcessingUtils.mapLayerFromString(layer, self.context)
         self.widget.setLayer(layer)
 
     def setValue(self, value):
@@ -1433,6 +1441,7 @@ def selectFile(self):
                 self.combo.setCurrentIndex(self.combo.findText(filename))
             else:
                 self.combo.setEditText(filename)
+            self.widgetValueHasChanged.emit(self)
 
     def setValue(self, value):
         if value is None or value == NULL:
@@ -1450,6 +1459,7 @@ def setValue(self, value):
             return self.widget.setText(value)
         else:
             self.setComboValue(value, combobox=self.combo)
+        self.widgetValueHasChanged.emit(self)
 
     def value(self):
         if self.dialogType == DIALOG_STANDARD:
@@ -1473,6 +1483,10 @@ def validator(v):
 class TableFieldWidgetWrapper(WidgetWrapper):
     NOT_SET = '[Not set]'
 
+    def __init__(self, param, dialog, row=0, col=0, **kwargs):
+        super().__init__(param, dialog, row, col, **kwargs)
+        self.context = dataobjects.createContext()
+
     def createWidget(self):
         self._layer = None
 
@@ -1516,11 +1530,10 @@ def parentValueChanged(self, wrapper):
         self.setLayer(wrapper.value())
 
     def setLayer(self, layer):
-        context = dataobjects.createContext()
         if isinstance(layer, QgsProcessingFeatureSourceDefinition):
-            layer, ok = layer.source.valueAsString(context.expressionContext())
+            layer, ok = layer.source.valueAsString(self.context.expressionContext())
         if isinstance(layer, str):
-            layer = QgsProcessingUtils.mapLayerFromString(layer, context)
+            layer = QgsProcessingUtils.mapLayerFromString(layer, self.context)
         self._layer = layer
         self.refreshItems()
 
@@ -1595,6 +1608,10 @@ def validator(v):
 class BandWidgetWrapper(WidgetWrapper):
     NOT_SET = '[Not set]'
 
+    def __init__(self, param, dialog, row=0, col=0, **kwargs):
+        super().__init__(param, dialog, row, col, **kwargs)
+        self.context = dataobjects.createContext()
+
     def createWidget(self):
         self._layer = None
 
@@ -1626,11 +1643,10 @@ def parentValueChanged(self, wrapper):
         self.setLayer(wrapper.value())
 
     def setLayer(self, layer):
-        context = dataobjects.createContext()
         if isinstance(layer, QgsProcessingParameterRasterLayer):
-            layer, ok = layer.source.valueAsString(context.expressionContext())
+            layer, ok = layer.source.valueAsString(self.context.expressionContext())
         if isinstance(layer, str):
-            layer = QgsProcessingUtils.mapLayerFromString(layer, context)
+            layer = QgsProcessingUtils.mapLayerFromString(layer, self.context)
         self._layer = layer
         self.refreshItems()