[processing] Don't throw an exception if an expression cannot

be prepared There's cases where this happens without reflecting an invalid expression. So we can try to prepare, but not abort if the preparation fails. Fixes #18103
qgis · Feb 15, 2018 · a811036 · a811036
1 parent e0b1d37
commit a811036
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diff --git a/python/plugins/processing/algs/qgis/FieldsCalculator.py b/python/plugins/processing/algs/qgis/FieldsCalculator.py
@@ -123,9 +123,7 @@ def processAlgorithm(self, parameters, context, feedback):
         if layer is not None:
             exp_context.appendScope(QgsExpressionContextUtils.layerScope(layer))
 
-        if not expression.prepare(exp_context):
-            raise QgsProcessingException(
-                self.tr('Evaluation error: {0}').format(expression.parserErrorString()))
+        expression.prepare(exp_context)
 
         features = source.getFeatures()
         total = 100.0 / source.featureCount() if source.featureCount() else 0

diff --git a/python/plugins/processing/algs/qgis/RandomPointsPolygons.py b/python/plugins/processing/algs/qgis/RandomPointsPolygons.py
@@ -116,9 +116,7 @@ def processAlgorithm(self, parameters, context, feedback):
             raise QgsProcessingException(expression.parserErrorString())
 
         expressionContext = self.createExpressionContext(parameters, context, source)
-        if not expression.prepare(expressionContext):
-            raise QgsProcessingException(
-                self.tr('Evaluation error: {0}').format(expression.evalErrorString()))
+        expression.prepare(expressionContext)
 
         fields = QgsFields()
         fields.append(QgsField('id', QVariant.Int, '', 10, 0))