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Tweak processing API to better handle dynamic properties

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This commit is contained in:
Nyall Dawson 2017-11-27 07:53:38 +10:00
parent 58ab507717
commit 86958937ad
3 changed files with 14 additions and 3 deletions
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2
python/core/processing/qgsprocessingalgorithm.sip
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@ -872,7 +872,7 @@ class QgsProcessingFeatureBasedAlgorithm : QgsProcessingAlgorithm
:rtype: QgsCoordinateReferenceSystem
%End
virtual QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) = 0;
virtual QgsFeature processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) = 0;
%Docstring
Processes an individual input ``feature`` from the source. Algorithms should implement their
logic in this method for performing the algorithm's operation (e.g. replacing the feature's

13
src/core/processing/qgsprocessingalgorithm.cpp
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@ -699,6 +699,13 @@ QVariantMap QgsProcessingFeatureBasedAlgorithm::processAlgorithm( const QVariant
if ( !sink )
return QVariantMap();
// prepare expression context for feature iteration
QgsExpressionContext prevContext = context.expressionContext();
QgsExpressionContext algContext = prevContext;
algContext.appendScopes( createExpressionContext( parameters, context, dynamic_cast< QgsProcessingFeatureSource * >( mSource.get() ) ).takeScopes() );
context.setExpressionContext( algContext );
long count = mSource->featureCount();
QgsFeature f;
@ -713,7 +720,8 @@ QVariantMap QgsProcessingFeatureBasedAlgorithm::processAlgorithm( const QVariant
break;
}
QgsFeature transformed = processFeature( f, feedback );
context.expressionContext().setFeature( f );
QgsFeature transformed = processFeature( f, context, feedback );
if ( transformed.isValid() )
sink->addFeature( transformed, QgsFeatureSink::FastInsert );
@ -723,6 +731,9 @@ QVariantMap QgsProcessingFeatureBasedAlgorithm::processAlgorithm( const QVariant
mSource.reset();
// probably not necessary - context's aren't usually recycled, but can't hurt
context.setExpressionContext( prevContext );
QVariantMap outputs;
outputs.insert( QStringLiteral( "OUTPUT" ), dest );
return outputs;

2
src/core/processing/qgsprocessingalgorithm.h
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@ -874,7 +874,7 @@ class CORE_EXPORT QgsProcessingFeatureBasedAlgorithm : public QgsProcessingAlgor
* can break valid model execution - so use with extreme caution, and consider using
* \a feedback to instead report non-fatal processing failures for features instead.
*/
virtual QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) = 0;
virtual QgsFeature processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) = 0;
virtual QVariantMap processAlgorithm( const QVariantMap &parameters,
QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;