Expose compatible vector layer parameter evaluation to QgsProcessingAlgorithm

Author: nyalldawson

python/core/processing/qgsprocessingalgorithm.sip

@@ -514,7 +514,7 @@ class QgsProcessingAlgorithm
 
     QgsProcessingFeatureSource *parameterAsSource( const QVariantMap &parameters, const QString &name, QgsProcessingContext &context ) const /Factory/;
 %Docstring
- Evaluates the parameter with matching ``definition`` to a feature source.
+ Evaluates the parameter with matching ``name`` to a feature source.
 
  Sources will either be taken from ``context``'s active project, or loaded from external
  sources and stored temporarily in the ``context``.
@@ -523,6 +523,22 @@ class QgsProcessingAlgorithm
  :rtype: QgsProcessingFeatureSource
 %End
 
+    QString parameterAsCompatibleSourceLayerPath( const QVariantMap &parameters, const QString &name,
+        QgsProcessingContext &context, const QStringList &compatibleFormats, const QString &preferredFormat = QString( "shp" ), QgsProcessingFeedback *feedback = 0 );
+%Docstring
+ Evaluates the parameter with matching ``name`` to a source vector layer file path of compatible format.
+
+ If the parameter is evaluated to an existing layer, and that layer is not of the format listed in the
+ ``compatibleFormats`` argument, then the layer will first be exported to a compatible format
+ in a temporary location. The function will then return the path to that temporary file.
+
+ ``compatibleFormats`` should consist entirely of lowercase file extensions, e.g. 'shp'.
+
+ The ``preferredFormat`` argument is used to specify to desired file extension to use when a temporary
+ layer export is required.
+ :rtype: str
+%End
+
     QgsMapLayer *parameterAsLayer( const QVariantMap &parameters, const QString &name, QgsProcessingContext &context ) const;
 %Docstring
  Evaluates the parameter with matching ``name`` to a map layer.

src/core/processing/qgsprocessingalgorithm.cpp

@@ -503,6 +503,11 @@ QgsProcessingFeatureSource *QgsProcessingAlgorithm::parameterAsSource( const QVa
   return QgsProcessingParameters::parameterAsSource( parameterDefinition( name ), parameters, context );
 }
 
+QString QgsProcessingAlgorithm::parameterAsCompatibleSourceLayerPath( const QVariantMap &parameters, const QString &name, QgsProcessingContext &context, const QStringList &compatibleFormats, const QString &preferredFormat, QgsProcessingFeedback *feedback )
+{
+  return QgsProcessingParameters::parameterAsCompatibleSourceLayerPath( parameterDefinition( name ), parameters, context, compatibleFormats, preferredFormat, feedback );
+}
+
 QgsMapLayer *QgsProcessingAlgorithm::parameterAsLayer( const QVariantMap &parameters, const QString &name, QgsProcessingContext &context ) const
 {
   return QgsProcessingParameters::parameterAsLayer( parameterDefinition( name ), parameters, context );

src/core/processing/qgsprocessingalgorithm.h

@@ -30,6 +30,7 @@
 class QgsProcessingProvider;
 class QgsProcessingFeedback;
 class QgsFeatureSink;
+class QgsProcessingFeedback;
 
 
 /**
@@ -485,7 +486,7 @@ class CORE_EXPORT QgsProcessingAlgorithm
                                      const QgsFields &fields, QgsWkbTypes::Type geometryType = QgsWkbTypes::NoGeometry, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem() ) const SIP_FACTORY;
 
     /**
-     * Evaluates the parameter with matching \a definition to a feature source.
+     * Evaluates the parameter with matching \a name to a feature source.
      *
      * Sources will either be taken from \a context's active project, or loaded from external
      * sources and stored temporarily in the \a context.
@@ -494,6 +495,21 @@ class CORE_EXPORT QgsProcessingAlgorithm
      */
     QgsProcessingFeatureSource *parameterAsSource( const QVariantMap &parameters, const QString &name, QgsProcessingContext &context ) const SIP_FACTORY;
 
+    /**
+     * Evaluates the parameter with matching \a name to a source vector layer file path of compatible format.
+     *
+     * If the parameter is evaluated to an existing layer, and that layer is not of the format listed in the
+     * \a compatibleFormats argument, then the layer will first be exported to a compatible format
+     * in a temporary location. The function will then return the path to that temporary file.
+     *
+     * \a compatibleFormats should consist entirely of lowercase file extensions, e.g. 'shp'.
+     *
+     * The \a preferredFormat argument is used to specify to desired file extension to use when a temporary
+     * layer export is required.
+     */
+    QString parameterAsCompatibleSourceLayerPath( const QVariantMap &parameters, const QString &name,
+        QgsProcessingContext &context, const QStringList &compatibleFormats, const QString &preferredFormat = QString( "shp" ), QgsProcessingFeedback *feedback = nullptr );
+
     /**
      * Evaluates the parameter with matching \a name to a map layer.
      *