QGIS API Documentation 3.39.0-Master (67e056379ed)
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qgsalgorithmattributeindex.cpp
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1/***************************************************************************
2 qgsalgorithmattributeraster.cpp
3 ---------------------
4 begin : November 2019
5 copyright : (C) 2019 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 "qgsvectorlayer.h"
21
23
24QString QgsAttributeIndexAlgorithm::name() const
25{
26 return QStringLiteral( "createattributeindex" );
27}
28
29QString QgsAttributeIndexAlgorithm::displayName() const
30{
31 return QObject::tr( "Create attribute index" );
32}
33
34QStringList QgsAttributeIndexAlgorithm::tags() const
35{
36 return QObject::tr( "table,attribute,index,create,vector" ).split( ',' );
37}
38
39QString QgsAttributeIndexAlgorithm::group() const
40{
41 return QObject::tr( "Vector general" );
42}
43
44QString QgsAttributeIndexAlgorithm::groupId() const
45{
46 return QStringLiteral( "vectorgeneral" );
47}
48
49Qgis::ProcessingAlgorithmFlags QgsAttributeIndexAlgorithm::flags() const
50{
52}
53
54
55QString QgsAttributeIndexAlgorithm::shortHelpString() const
56{
57 return QObject::tr( "Creates an index to speed up queries made against "
58 "a field in a table. Support for index creation is "
59 "dependent on the layer's data provider and the field type." );
60}
61
62QgsAttributeIndexAlgorithm *QgsAttributeIndexAlgorithm::createInstance() const
63{
64 return new QgsAttributeIndexAlgorithm();
65}
66
67void QgsAttributeIndexAlgorithm::initAlgorithm( const QVariantMap & )
68{
69 addParameter( new QgsProcessingParameterVectorLayer( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ), QList<int> { static_cast< int >( Qgis::ProcessingSourceType::Vector ) } ) );
70 addParameter( new QgsProcessingParameterField( QStringLiteral( "FIELD" ), QObject::tr( "Attribute to index" ), QVariant(), QStringLiteral( "INPUT" ) ) );
71
72 addOutput( new QgsProcessingOutputVectorLayer( QStringLiteral( "OUTPUT" ), QObject::tr( "Indexed layer" ) ) );
73}
74
75QVariantMap QgsAttributeIndexAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
76{
77 QgsVectorLayer *layer = parameterAsVectorLayer( parameters, QStringLiteral( "INPUT" ), context );
78
79 if ( !layer )
80 throw QgsProcessingException( QObject::tr( "Could not load source layer for %1." ).arg( QLatin1String( "INPUT" ) ) );
81
82 const QString field = parameterAsString( parameters, QStringLiteral( "FIELD" ), context );
83
84 QgsVectorDataProvider *provider = layer->dataProvider();
85
86 const int fieldIndex = layer->fields().lookupField( field );
87 if ( fieldIndex < 0 || layer->fields().fieldOrigin( fieldIndex ) != Qgis::FieldOrigin::Provider )
88 {
89 feedback->pushInfo( QObject::tr( "Can not create attribute index on %1" ).arg( field ) );
90 }
91 else
92 {
93 const int providerIndex = layer->fields().fieldOriginIndex( fieldIndex );
95 {
96 if ( !provider->createAttributeIndex( providerIndex ) )
97 {
98 feedback->pushInfo( QObject::tr( "Could not create attribute index" ) );
99 }
100 }
101 else
102 {
103 feedback->pushInfo( QObject::tr( "Layer's data provider does not support creating attribute indexes" ) );
104 }
105 }
106
107 QVariantMap outputs;
108 outputs.insert( QStringLiteral( "OUTPUT" ), layer->id() );
109 return outputs;
110}
111
@ Vector
Tables (i.e. vector layers with or without geometry). When used for a sink this indicates the sink ha...
QFlags< ProcessingAlgorithmFlag > ProcessingAlgorithmFlags
Flags indicating how and when an algorithm operates and should be exposed to users.
Definition qgis.h:3076
@ Provider
Field originates from the underlying data provider of the vector layer.
@ NoThreading
Algorithm is not thread safe and cannot be run in a background thread, e.g. for algorithms which mani...
int fieldOriginIndex(int fieldIdx) const
Returns the field's origin index (its meaning is specific to each type of origin).
Q_INVOKABLE int lookupField(const QString &fieldName) const
Looks up field's index from the field name.
QString id
Definition qgsmaplayer.h:78
virtual Qgis::ProcessingAlgorithmFlags flags() const
Returns the flags indicating how and when the algorithm operates and should be exposed to users.
Contains information about the context in which a processing algorithm is executed.
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 vector layer output for processing algorithms.
A vector layer or feature source field parameter for processing algorithms.
A vector layer (with or without geometry) parameter for processing algorithms.
This is the base class for vector data providers.
@ CreateAttributeIndex
Can create indexes on provider's fields.
virtual bool createAttributeIndex(int field)
Create an attribute index on the datasource.
virtual Q_INVOKABLE QgsVectorDataProvider::Capabilities capabilities() const
Returns flags containing the supported capabilities.
Represents a vector layer which manages a vector based data sets.
QgsVectorDataProvider * dataProvider() FINAL
Returns the layer's data provider, it may be nullptr.