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Add method to match feature attributes to the given fields

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Refs #18784
This commit is contained in:
Nyall Dawson 2018-09-24 10:40:46 +10:00
parent 81487f9f18
commit a8794001e0
3 changed files with 58 additions and 0 deletions
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10
python/core/auto_generated/qgsvectorlayerutils.sip.in
View File

@ -156,6 +156,16 @@ The duplicated feature will be automatically inserted into the layer.
.. versionadded:: 3.0
%End
static void matchAttributesToFields( QgsFeature &feature, const QgsFields &fields );
%Docstring
Matches the attributes in ``feature`` to the specified ``fields``.
This causes the attributes contained within the given ``feature`` to be rearranged (or in
some cases dropped) in order to match the fields and order indicated by ``fields``.
.. versionadded:: 3.4
%End
};

38
src/core/qgsvectorlayerutils.cpp
View File

@ -522,6 +522,44 @@ std::unique_ptr<QgsVectorLayerFeatureSource> QgsVectorLayerUtils::getFeatureSour
return featureSource;
}
void QgsVectorLayerUtils::matchAttributesToFields( QgsFeature &feature, const QgsFields &fields )
{
if ( !feature.fields().isEmpty() )
{
QgsAttributes attributes;
attributes.reserve( fields.size() );
// feature has a field mapping, so we can match attributes to field names
for ( const QgsField &field : fields )
{
int index = feature.fields().lookupField( field.name() );
attributes.append( index >= 0 ? feature.attribute( index ) : QVariant( field.type() ) );
}
feature.setAttributes( attributes );
}
else
{
// no field name mapping in feature, just use order
const int lengthDiff = feature.attributes().count() - fields.count();
if ( lengthDiff > 0 )
{
// truncate extra attributes
QgsAttributes attributes = feature.attributes().mid( 0, fields.count() );
feature.setAttributes( attributes );
}
else if ( lengthDiff < 0 )
{
// add missing null attributes
QgsAttributes attributes = feature.attributes();
attributes.reserve( fields.count() );
for ( int i = feature.attributes().count(); i < fields.count(); ++i )
{
attributes.append( QVariant( fields.at( i ).type() ) );
}
feature.setAttributes( attributes );
}
}
}
QList<QgsVectorLayer *> QgsVectorLayerUtils::QgsDuplicateFeatureContext::layers() const
{
QList<QgsVectorLayer *> layers;

10
src/core/qgsvectorlayerutils.h
View File

@ -167,6 +167,16 @@ class CORE_EXPORT QgsVectorLayerUtils
* \since QGIS 3.4
*/
static std::unique_ptr<QgsVectorLayerFeatureSource> getFeatureSource( QPointer<QgsVectorLayer> layer ) SIP_SKIP;
/**
* Matches the attributes in \a feature to the specified \a fields.
*
* This causes the attributes contained within the given \a feature to be rearranged (or in
* some cases dropped) in order to match the fields and order indicated by \a fields.
*
* \since QGIS 3.4
*/
static void matchAttributesToFields( QgsFeature &feature, const QgsFields &fields );
};