When calling processing.run() and an QgsProcessingExpection occurs,

don't raise a generic "something went wrong" exception but instead ensure that the original exception with the proper error message is raised for catching in Python instead
qgis · Oct 8, 2020 · 2207c30 · 2207c30
1 parent ee7bea2
commit 2207c30
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Showing 5 changed files with 27 additions and 12 deletions.
diff --git a/python/core/auto_generated/processing/qgsprocessingalgorithm.sip.in b/python/core/auto_generated/processing/qgsprocessingalgorithm.sip.in
@@ -337,7 +337,8 @@ is passed in order to make a best guess determination of the output properties.
 .. versionadded:: 3.14
 %End
 
-    QVariantMap run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok /Out/ = 0, const QVariantMap &configuration = QVariantMap() ) const;
+    QVariantMap run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok /Out/ = 0, const QVariantMap &configuration = QVariantMap(),
+                     bool catchExceptions = true ) const throw( QgsProcessingException );
 %Docstring
 Executes the algorithm using the specified ``parameters``. This method internally
 creates a copy of the algorithm before running it, so it is safe to call
@@ -349,6 +350,9 @@ Algorithm progress should be reported using the supplied ``feedback`` object.
 
 If specified, ``ok`` will be set to ``True`` if algorithm was successfully run.
 
+If ``catchExceptions`` is set to ``False``, then QgsProcessingExceptions raised during
+the algorithm run will not be automatically caught and will be raised instead.
+
 :return: A map of algorithm outputs. These may be output layer references, or calculated
          values such as statistical calculations.
 

diff --git a/python/plugins/processing/core/Processing.py b/python/plugins/processing/core/Processing.py
@@ -156,7 +156,7 @@ def runAlgorithm(algOrName, parameters, onFinish=None, feedback=None, context=No
             feedback.pushInfo(
                 Processing.tr('Warning: Not all input layers use the same CRS.\nThis can cause unexpected results.'))
 
-        ret, results = execute(alg, parameters, context, feedback)
+        ret, results = execute(alg, parameters, context, feedback, catch_exceptions=False)
         if ret:
             feedback.pushInfo(
                 Processing.tr('Results: {}').format(results))

diff --git a/python/plugins/processing/gui/AlgorithmExecutor.py b/python/plugins/processing/gui/AlgorithmExecutor.py
@@ -45,7 +45,7 @@
 from qgis.utils import iface
 
 
-def execute(alg, parameters, context=None, feedback=None):
+def execute(alg, parameters, context=None, feedback=None, catch_exceptions=True):
     """Executes a given algorithm, showing its progress in the
     progress object passed along.
 
@@ -58,14 +58,18 @@ def execute(alg, parameters, context=None, feedback=None):
     if context is None:
         context = dataobjects.createContext(feedback)
 
-    try:
-        results, ok = alg.run(parameters, context, feedback)
+    if catch_exceptions:
+        try:
+            results, ok = alg.run(parameters, context, feedback)
+            return ok, results
+        except QgsProcessingException as e:
+            QgsMessageLog.logMessage(str(sys.exc_info()[0]), 'Processing', Qgis.Critical)
+            if feedback is not None:
+                feedback.reportError(e.msg)
+            return False, {}
+    else:
+        results, ok = alg.run(parameters, context, feedback, {}, False)
         return ok, results
-    except QgsProcessingException as e:
-        QgsMessageLog.logMessage(str(sys.exc_info()[0]), 'Processing', Qgis.Critical)
-        if feedback is not None:
-            feedback.reportError(e.msg)
-        return False, {}
 
 
 def execute_in_place_run(alg, parameters, context=None, feedback=None, raise_exceptions=False):

diff --git a/src/core/processing/qgsprocessingalgorithm.cpp b/src/core/processing/qgsprocessingalgorithm.cpp
@@ -445,7 +445,7 @@ QgsProcessingAlgorithm::VectorProperties QgsProcessingAlgorithm::sinkProperties(
   return VectorProperties();
 }
 
-QVariantMap QgsProcessingAlgorithm::run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok, const QVariantMap &configuration ) const
+QVariantMap QgsProcessingAlgorithm::run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok, const QVariantMap &configuration, bool catchExceptions ) const
 {
   std::unique_ptr< QgsProcessingAlgorithm > alg( create( configuration ) );
   if ( ok )
@@ -462,6 +462,9 @@ QVariantMap QgsProcessingAlgorithm::run( const QVariantMap &parameters, QgsProce
   }
   catch ( QgsProcessingException &e )
   {
+    if ( !catchExceptions )
+      throw e;
+
     QgsMessageLog::logMessage( e.what(), QObject::tr( "Processing" ), Qgis::Critical );
     feedback->reportError( e.what() );
     return QVariantMap();

diff --git a/src/core/processing/qgsprocessingalgorithm.h b/src/core/processing/qgsprocessingalgorithm.h
@@ -378,13 +378,17 @@ class CORE_EXPORT QgsProcessingAlgorithm
      *
      * If specified, \a ok will be set to TRUE if algorithm was successfully run.
      *
+     * If \a catchExceptions is set to FALSE, then QgsProcessingExceptions raised during
+     * the algorithm run will not be automatically caught and will be raised instead.
+     *
      * \returns A map of algorithm outputs. These may be output layer references, or calculated
      * values such as statistical calculations.
      *
      * \note this method can only be called from the main thread. Use prepare(), runPrepared() and postProcess()
      * if you need to run algorithms from a background thread, or use the QgsProcessingAlgRunnerTask class.
      */
-    QVariantMap run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok SIP_OUT = nullptr, const QVariantMap &configuration = QVariantMap() ) const;
+    QVariantMap run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok SIP_OUT = nullptr, const QVariantMap &configuration = QVariantMap(),
+                     bool catchExceptions = true ) const SIP_THROW( QgsProcessingException );
 
     /**
      * Prepares the algorithm for execution. This must be run in the main thread, and allows the algorithm