QGIS API Documentation 3.39.0-Master (67e056379ed)
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qgsalgorithmsplitvectorlayer.cpp
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1/***************************************************************************
2 qgsalgorithmsplitvectorlayer.cpp
3 ---------------------
4 begin : May 2020
5 copyright : (C) 2020 by Alexander Bruy
6 email : alexander dot bruy at gmail dot com
7 ***************************************************************************/
8
9/***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
19#include "qgsvectorfilewriter.h"
20#include "qgsvariantutils.h"
21#include "qgsfileutils.h"
22
24
25QString QgsSplitVectorLayerAlgorithm::name() const
26{
27 return QStringLiteral( "splitvectorlayer" );
28}
29
30QString QgsSplitVectorLayerAlgorithm::displayName() const
31{
32 return QObject::tr( "Split vector layer" );
33}
34
35QStringList QgsSplitVectorLayerAlgorithm::tags() const
36{
37 return QObject::tr( "vector,split,field,unique" ).split( ',' );
38}
39
40QString QgsSplitVectorLayerAlgorithm::group() const
41{
42 return QObject::tr( "Vector general" );
43}
44
45QString QgsSplitVectorLayerAlgorithm::groupId() const
46{
47 return QStringLiteral( "vectorgeneral" );
48}
49
50QString QgsSplitVectorLayerAlgorithm::shortHelpString() const
51{
52 return QObject::tr( "Splits input vector layer into multiple layers by specified unique ID field." )
53 + QStringLiteral( "\n\n" )
54 + QObject::tr( "Each of the layers created in the output folder contains all features from "
55 "the input layer with the same value for the specified attribute. The number "
56 "of files generated is equal to the number of different values found for the "
57 "specified attribute." );
58}
59
60QgsSplitVectorLayerAlgorithm *QgsSplitVectorLayerAlgorithm::createInstance() const
61{
62 return new QgsSplitVectorLayerAlgorithm();
63}
64
65void QgsSplitVectorLayerAlgorithm::initAlgorithm( const QVariantMap & )
66{
67 addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ), QList<int>() << static_cast< int >( Qgis::ProcessingSourceType::Vector ) ) );
68 addParameter( new QgsProcessingParameterField( QStringLiteral( "FIELD" ), QObject::tr( "Unique ID field" ),
69 QVariant(), QStringLiteral( "INPUT" ) ) );
70 std::unique_ptr< QgsProcessingParameterBoolean > prefixFieldParam = std::make_unique< QgsProcessingParameterBoolean >( QStringLiteral( "PREFIX_FIELD" ),
71 QObject::tr( "Add field prefix to file names" ), true );
72 addParameter( prefixFieldParam.release() );
73
74 const QStringList options = QgsVectorFileWriter::supportedFormatExtensions();
75 auto fileTypeParam = std::make_unique < QgsProcessingParameterEnum >( QStringLiteral( "FILE_TYPE" ), QObject::tr( "Output file type" ), options, false, 0, true );
76 fileTypeParam->setFlags( fileTypeParam->flags() | Qgis::ProcessingParameterFlag::Advanced );
77 addParameter( fileTypeParam.release() );
78
79 addParameter( new QgsProcessingParameterFolderDestination( QStringLiteral( "OUTPUT" ), QObject::tr( "Output directory" ) ) );
80 addOutput( new QgsProcessingOutputMultipleLayers( QStringLiteral( "OUTPUT_LAYERS" ), QObject::tr( "Output layers" ) ) );
81}
82
83QVariantMap QgsSplitVectorLayerAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
84{
85 std::unique_ptr< QgsProcessingFeatureSource > source( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
86 if ( !source )
87 throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT" ) ) );
88
89 const QString fieldName = parameterAsString( parameters, QStringLiteral( "FIELD" ), context );
90 const QString outputDir = parameterAsString( parameters, QStringLiteral( "OUTPUT" ), context );
91 QString outputFormat;
92 if ( parameters.value( QStringLiteral( "FILE_TYPE" ) ).isValid() )
93 {
94 const int idx = parameterAsEnum( parameters, QStringLiteral( "FILE_TYPE" ), context );
95 outputFormat = QgsVectorFileWriter::supportedFormatExtensions().at( idx );
96 }
97 else
98 {
99 outputFormat = context.preferredVectorFormat();
100 if ( !QgsVectorFileWriter::supportedFormatExtensions().contains( outputFormat, Qt::CaseInsensitive ) )
101 outputFormat = QStringLiteral( "gpkg" );
102 }
103
104 if ( !QDir().mkpath( outputDir ) )
105 throw QgsProcessingException( QStringLiteral( "Failed to create output directory." ) );
106
107 const QgsFields fields = source->fields();
108 const QgsCoordinateReferenceSystem crs = source->sourceCrs();
109 const Qgis::WkbType geometryType = source->wkbType();
110 const int fieldIndex = fields.lookupField( fieldName );
111 const QSet< QVariant > uniqueValues = source->uniqueValues( fieldIndex );
112 QString baseName = outputDir + QDir::separator();
113
114 if ( parameterAsBool( parameters, QStringLiteral( "PREFIX_FIELD" ), context ) )
115 {
116 baseName.append( fieldName + "_" );
117 }
118
119 int current = 0;
120 const double step = uniqueValues.size() > 0 ? 100.0 / uniqueValues.size() : 1;
121
122 int count = 0;
123 QgsFeature feat;
124 QStringList outputLayers;
125 std::unique_ptr< QgsFeatureSink > sink;
126
127 for ( auto it = uniqueValues.constBegin(); it != uniqueValues.constEnd(); ++it )
128 {
129 if ( feedback->isCanceled() )
130 break;
131
132 QString fileName;
133 if ( QgsVariantUtils::isNull( *it ) )
134 {
135 fileName = QStringLiteral( "%1NULL.%2" ).arg( baseName ).arg( outputFormat );
136 }
137 else if ( ( *it ).toString().isEmpty() )
138 {
139 fileName = QStringLiteral( "%1EMPTY.%2" ).arg( baseName ).arg( outputFormat );
140 }
141 else
142 {
143 fileName = QStringLiteral( "%1%2.%3" ).arg( baseName ).arg( QgsFileUtils::stringToSafeFilename( ( *it ).toString() ) ).arg( outputFormat );
144 }
145 feedback->pushInfo( QObject::tr( "Creating layer: %1" ).arg( fileName ) );
146
147 sink.reset( QgsProcessingUtils::createFeatureSink( fileName, context, fields, geometryType, crs ) );
148 const QString expr = QgsExpression::createFieldEqualityExpression( fieldName, *it );
149 QgsFeatureIterator features = source->getFeatures( QgsFeatureRequest().setFilterExpression( expr ), Qgis::ProcessingFeatureSourceFlag::SkipGeometryValidityChecks );
150 count = 0;
151 while ( features.nextFeature( feat ) )
152 {
153 if ( feedback->isCanceled() )
154 break;
155
156 if ( !sink->addFeature( feat, QgsFeatureSink::FastInsert ) )
157 throw QgsProcessingException( writeFeatureError( sink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
158 count += 1;
159 }
160
161 feedback->pushInfo( QObject::tr( "Added %n feature(s) to layer", nullptr, count ) );
162 outputLayers << fileName;
163
164 current += 1;
165 feedback->setProgress( current * step );
166 }
167
168 QVariantMap outputs;
169 outputs.insert( QStringLiteral( "OUTPUT" ), outputDir );
170 outputs.insert( QStringLiteral( "OUTPUT_LAYERS" ), outputLayers );
171 return outputs;
172}
173
@ Vector
Tables (i.e. vector layers with or without geometry). When used for a sink this indicates the sink ha...
@ SkipGeometryValidityChecks
Invalid geometry checks should always be skipped. This flag can be useful for algorithms which always...
WkbType
The WKB type describes the number of dimensions a geometry has.
Definition qgis.h:201
@ Advanced
Parameter is an advanced parameter which should be hidden from users by default.
This class represents a coordinate reference system (CRS).
static QString createFieldEqualityExpression(const QString &fieldName, const QVariant &value, QMetaType::Type fieldType=QMetaType::Type::UnknownType)
Create an expression allowing to evaluate if a field is equal to a value.
Wrapper for iterator of features from vector data provider or vector layer.
bool nextFeature(QgsFeature &f)
Fetch next feature and stores in f, returns true on success.
This class wraps a request for features to a vector layer (or directly its vector data provider).
@ FastInsert
Use faster inserts, at the cost of updating the passed features to reflect changes made at the provid...
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:58
bool isCanceled() const
Tells whether the operation has been canceled already.
Definition qgsfeedback.h:53
void setProgress(double progress)
Sets the current progress for the feedback object.
Definition qgsfeedback.h:61
Container of fields for a vector layer.
Definition qgsfields.h:46
Q_INVOKABLE int lookupField(const QString &fieldName) const
Looks up field's index from the field name.
static QString stringToSafeFilename(const QString &string)
Converts a string to a safe filename, replacing characters which are not safe for filenames with an '...
Contains information about the context in which a processing algorithm is executed.
QString preferredVectorFormat() const
Returns the preferred vector format to use for vector outputs.
Custom exception class for processing related exceptions.
Base class for providing feedback from a processing algorithm.
virtual void pushInfo(const QString &info)
Pushes a general informational message from the algorithm.
A multi-layer output for processing algorithms which create map layers, when the number and nature of...
An input feature source (such as vector layers) parameter for processing algorithms.
A vector layer or feature source field parameter for processing algorithms.
A folder destination parameter, for specifying the destination path for a folder created by the algor...
static QgsFeatureSink * createFeatureSink(QString &destination, QgsProcessingContext &context, const QgsFields &fields, Qgis::WkbType geometryType, const QgsCoordinateReferenceSystem &crs, const QVariantMap &createOptions=QVariantMap(), const QStringList &datasourceOptions=QStringList(), const QStringList &layerOptions=QStringList(), QgsFeatureSink::SinkFlags sinkFlags=QgsFeatureSink::SinkFlags(), QgsRemappingSinkDefinition *remappingDefinition=nullptr)
Creates a feature sink ready for adding features.
static bool isNull(const QVariant &variant, bool silenceNullWarnings=false)
Returns true if the specified variant should be considered a NULL value.
static QStringList supportedFormatExtensions(VectorFormatOptions options=SortRecommended)
Returns a list of file extensions for supported formats, e.g "shp", "gpkg".
const QgsCoordinateReferenceSystem & crs