Report success or failure after running algs

And auto catch python exceptions and report failure of model

Author: nyalldawson

python/core/processing/qgsprocessingalgorithm.sip

@@ -215,14 +215,16 @@ class QgsProcessingAlgorithm
 %End
 
     QVariantMap run( const QVariantMap &parameters,
-                     QgsProcessingContext &context, QgsProcessingFeedback *feedback ) const;
+                     QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok /Out/ = 0 ) const;
 %Docstring
  Executes the algorithm using the specified ``parameters``.
 
  The ``context`` argument specifies the context in which the algorithm is being run.
 
  Algorithm progress should be reported using the supplied ``feedback`` object.
 
+ If specified, ``ok`` will be set to true if algorithm was successfully run.
+
  :return: A map of algorithm outputs. These may be output layer references, or calculated
  values such as statistical calculations.
  :rtype: QVariantMap

python/plugins/processing/core/GeoAlgorithm.py

@@ -335,7 +335,7 @@ def executeAlgorithm(alg, parameters, context=None, feedback=None, model=None):
         #self.resolveOutputs()
         #self.evaluateParameterValues()
         #self.runPreExecutionScript(feedback)
-        result = alg.run(parameters, context, feedback)
+        result, ok = alg.run(parameters, context, feedback)
         #self.processAlgorithm(parameters, context, feedback)
         feedback.setProgress(100)
         return result

python/plugins/processing/gui/AlgorithmExecutor.py

@@ -59,8 +59,8 @@ def execute(alg, parameters, context=None, feedback=None):
         context = dataobjects.createContext()
 
     try:
-        results = alg.run(parameters, context, feedback)
-        return True, results
+        results, ok = alg.run(parameters, context, feedback)
+        return ok, results
     except GeoAlgorithmExecutionException as e:
         QgsMessageLog.logMessage(str(sys.exc_info()[0]), 'Processing', QgsMessageLog.CRITICAL)
         if feedback is not None:

python/plugins/processing/tests/AlgorithmsTestBase.py

@@ -128,14 +128,15 @@ def check_algorithm(self, name, defs):
 
         if expectFailure:
             try:
-                results = alg.run(parameters, context, feedback)
+                results, ok = alg.run(parameters, context, feedback)
                 self.check_results(results, context, defs['params'], defs['results'])
+                if ok:
+                    raise _UnexpectedSuccess
             except Exception:
                 pass
-            else:
-                raise _UnexpectedSuccess
         else:
-            results = alg.run(parameters, context, feedback)
+            results, ok = alg.run(parameters, context, feedback)
+            self.assertTrue(ok)
             self.check_results(results, context, defs['params'], defs['results'])
 
     def load_params(self, params):

src/core/processing/qgsprocessingalgorithm.cpp

@@ -23,6 +23,9 @@
 #include "qgsrectangle.h"
 #include "qgsprocessingcontext.h"
 #include "qgsprocessingutils.h"
+#include "qgsprocessingexception.h"
+#include "qgsmessagelog.h"
+#include "qgsprocessingfeedback.h"
 
 QgsProcessingAlgorithm::~QgsProcessingAlgorithm()
 {
@@ -311,9 +314,24 @@ bool QgsProcessingAlgorithm::hasHtmlOutputs() const
   return false;
 }
 
-QVariantMap QgsProcessingAlgorithm::run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) const
+QVariantMap QgsProcessingAlgorithm::run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok ) const
 {
-  return processAlgorithm( parameters, context, feedback );
+  if ( ok )
+    *ok = false;
+
+  QVariantMap results;
+  try
+  {
+    results = processAlgorithm( parameters, context, feedback );
+    if ( ok )
+      *ok = true;
+  }
+  catch ( QgsProcessingException &e )
+  {
+    QgsMessageLog::logMessage( e.what(), QObject::tr( "Processing" ), QgsMessageLog::CRITICAL );
+    feedback->reportError( e.what() );
+  }
+  return results;
 }
 
 QString QgsProcessingAlgorithm::parameterAsString( const QVariantMap &parameters, const QString &name, const QgsProcessingContext &context ) const

src/core/processing/qgsprocessingalgorithm.h

@@ -223,11 +223,13 @@ class CORE_EXPORT QgsProcessingAlgorithm
      *
      * Algorithm progress should be reported using the supplied \a feedback object.
      *
+     * If specified, \a ok will be set to true if algorithm was successfully run.
+     *
      * \returns A map of algorithm outputs. These may be output layer references, or calculated
      * values such as statistical calculations.
      */
     QVariantMap run( const QVariantMap &parameters,
-                     QgsProcessingContext &context, QgsProcessingFeedback *feedback ) const;
+                     QgsProcessingContext &context, QgsProcessingFeedback *feedback, bool *ok SIP_OUT = nullptr ) const;
 
     /**
      * If an algorithm subclass implements a custom parameters widget, a copy of this widget

src/core/processing/qgsprocessingalgrunnertask.cpp

@@ -39,8 +39,9 @@ void QgsProcessingAlgRunnerTask::cancel()
 bool QgsProcessingAlgRunnerTask::run()
 {
   connect( mFeedback.get(), &QgsFeedback::progressChanged, this, &QgsProcessingAlgRunnerTask::setProgress );
-  mResults = mAlgorithm->run( mParameters, mContext, mFeedback.get() );
-  return !mFeedback->isCanceled();
+  bool ok = false;
+  mResults = mAlgorithm->run( mParameters, mContext, mFeedback.get(), &ok );
+  return ok && !mFeedback->isCanceled();
 }
 
 void QgsProcessingAlgRunnerTask::finished( bool result )

src/core/processing/qgsprocessingexception.h

@@ -25,10 +25,15 @@
  * \class QgsProcessingException
  * \ingroup core
  * Custom exception class for processing related exceptions.
+ * \since QGIS 3.0
  */
 class CORE_EXPORT QgsProcessingException : public QgsException
 {
   public:
+
+    /**
+     * Constructor for QgsProcessingException.
+     */
     QgsProcessingException( const QString &what ) : QgsException( what ) {}
 
 };

src/core/processing/qgsprocessingmodelalgorithm.cpp

@@ -19,6 +19,7 @@
 #include "qgsprocessingregistry.h"
 #include "qgsprocessingfeedback.h"
 #include "qgsxmlutils.h"
+#include "qgsprocessingexception.h"
 #include <QFile>
 #include <QTextStream>
 
@@ -437,7 +438,14 @@ QVariantMap QgsProcessingModelAlgorithm::processAlgorithm( const QVariantMap &pa
       QTime childTime;
       childTime.start();
 
-      QVariantMap results = child.algorithm()->run( childParams, context, feedback );
+      bool ok = false;
+      QVariantMap results = child.algorithm()->run( childParams, context, feedback, &ok );
+      if ( !ok )
+      {
+        QString error = QObject::tr( "Error encountered while running %1" ).arg( child.description() );
+        feedback->reportError( error );
+        throw QgsProcessingException( error );
+      }
       childResults.insert( childId, results );
 
       // look through child alg's outputs to determine whether any of these should be copied
@@ -451,12 +459,6 @@ QVariantMap QgsProcessingModelAlgorithm::processAlgorithm( const QVariantMap &pa
 
       executed.insert( childId );
       feedback->pushDebugInfo( QObject::tr( "OK. Execution took %1 s (%2 outputs)." ).arg( childTime.elapsed() / 1000.0 ).arg( results.count() ) );
-#if 0
-    except GeoAlgorithmExecutionException as e:
-      feedback.pushDebugInfo( self.tr( 'Failed', 'ModelerAlgorithm' ) )
-      raise GeoAlgorithmExecutionException(
-        self.tr( 'Error executing algorithm {0}\n{1}', 'ModelerAlgorithm' ).format( alg.description, e.msg ) )
-#endif
     }
   }
   feedback->pushDebugInfo( QObject::tr( "Model processed ok. Executed %1 algorithms total in %2 s." ).arg( executed.count() ).arg( totalTime.elapsed() / 1000.0 ) );