QGIS API Documentation  2.99.0-Master (f867b65)
Classes | Public Member Functions | Static Public Member Functions | Properties | List of all members
QgsRelation Class Reference

#include <qgsrelation.h>

Classes

class  FieldPair
 Defines a relation between matching fields of the two involved tables of a relation. More...
 

Public Member Functions

 QgsRelation ()
 Default constructor. More...
 
void addFieldPair (const QString &referencingField, const QString &referencedField)
 Add a field pairs which is part of this relation The first element of each pair are the field names of the foreign key. More...
 
void addFieldPair (const FieldPair &fieldPair)
 Add a field pairs which is part of this relation The first element of each pair are the field names of the foreign key. More...
 
QList< QgsRelation::FieldPairfieldPairs () const
 Returns the field pairs which form this relation The first element of each pair are the field names of the foreign key. More...
 
void generateId ()
 Generate a (project-wide) unique id for this relation. More...
 
QgsFeature getReferencedFeature (const QgsFeature &feature) const
 Creates a request to return the feature on the referenced (parent) layer which is referenced by the provided feature. More...
 
QgsFeatureRequest getReferencedFeatureRequest (const QgsAttributes &attributes) const
 Creates a request to return the feature on the referenced (parent) layer which is referenced by the provided feature. More...
 
QgsFeatureRequest getReferencedFeatureRequest (const QgsFeature &feature) const
 Creates a request to return the feature on the referenced (parent) layer which is referenced by the provided feature. More...
 
QgsFeatureIterator getRelatedFeatures (const QgsFeature &feature) const
 Creates an iterator which returns all the features on the referencing (child) layer which have a foreign key pointing to the provided feature. More...
 
QString getRelatedFeaturesFilter (const QgsFeature &feature) const
 Returns a filter expression which returns all the features on the referencing (child) layer which have a foreign key pointing to the provided feature. More...
 
QgsFeatureRequest getRelatedFeaturesRequest (const QgsFeature &feature) const
 Creates a request to return all the features on the referencing (child) layer which have a foreign key pointing to the provided feature. More...
 
bool hasEqualDefinition (const QgsRelation &other) const
 Compares the two QgsRelation, ignoring the name and the ID. More...
 
QString id () const
 A (project-wide) unique id for this relation. More...
 
bool isValid () const
 Returns the validity of this relation. More...
 
QString name () const
 Returns a human readable name for this relation. More...
 
QgsAttributeList referencedFields () const
 Returns a list of attributes used to form the referenced fields (most likely primary key) on the referenced (parent) layer. More...
 
QgsVectorLayerreferencedLayer () const
 Access the referenced (parent) layer. More...
 
QString referencedLayerId () const
 Access the referenced (parent) layer's id. More...
 
QgsAttributeList referencingFields () const
 Returns a list of attributes used to form the referencing fields (foreign key) on the referencing (child) layer. More...
 
QgsVectorLayerreferencingLayer () const
 Access the referencing (child) layer This is the layer which has the field(s) which point to another layer. More...
 
QString referencingLayerId () const
 Access the referencing (child) layer's id This is the layer which has the field(s) which point to another layer. More...
 
Q_INVOKABLE QString resolveReferencedField (const QString &referencingField) const
 Get the referenced field counterpart given a referencing field. More...
 
Q_INVOKABLE QString resolveReferencingField (const QString &referencedField) const
 Get the referencing field counterpart given a referenced field. More...
 
void setId (const QString &id)
 Set an id for this relation. More...
 
void setName (const QString &name)
 Set a name for this relation. More...
 
void setReferencedLayer (const QString &id)
 Set the referenced (parent) layer id. More...
 
void setReferencingLayer (const QString &id)
 Set the referencing (child) layer id. More...
 
void writeXml (QDomNode &node, QDomDocument &doc) const
 Writes a relation to an XML structure. More...
 

Static Public Member Functions

static QgsRelation createFromXml (const QDomNode &node)
 Creates a relation from an XML structure. More...
 

Properties

QString id
 
bool isValid
 
QString name
 
QgsVectorLayer referencedLayer
 
QgsVectorLayer referencingLayer
 

Detailed Description

Definition at line 37 of file qgsrelation.h.

Constructor & Destructor Documentation

◆ QgsRelation()

QgsRelation::QgsRelation ( )

Default constructor.

Creates an invalid relation.

Definition at line 24 of file qgsrelation.cpp.

Member Function Documentation

◆ addFieldPair() [1/2]

void QgsRelation::addFieldPair ( const QString &  referencingField,
const QString &  referencedField 
)

Add a field pairs which is part of this relation The first element of each pair are the field names of the foreign key.

The second element of each pair are the field names of the matching primary key.

Parameters
referencingFieldThe field name on the referencing (child) layer (FK)
referencedFieldThe field name on the referenced (parent) layer (PK)

Definition at line 138 of file qgsrelation.cpp.

◆ addFieldPair() [2/2]

void QgsRelation::addFieldPair ( const FieldPair fieldPair)

Add a field pairs which is part of this relation The first element of each pair are the field names of the foreign key.

The second element of each pair are the field names of the matching primary key.

Parameters
fieldPairA pair of two strings
Note
not available in Python bindings

Definition at line 144 of file qgsrelation.cpp.

◆ createFromXml()

QgsRelation QgsRelation::createFromXml ( const QDomNode &  node)
static

Creates a relation from an XML structure.

Used for reading .qgs projects.

Parameters
nodeThe dom node containing the relation information
Returns
A relation

Definition at line 31 of file qgsrelation.cpp.

◆ fieldPairs()

QList< QgsRelation::FieldPair > QgsRelation::fieldPairs ( ) const

Returns the field pairs which form this relation The first element of each pair are the field names of the foreign key.

The second element of each pair are the field names of the matching primary key.

Returns
The fields forming the relation

Definition at line 251 of file qgsrelation.cpp.

◆ generateId()

void QgsRelation::generateId ( )

Generate a (project-wide) unique id for this relation.

Since
QGIS 3.0

Definition at line 221 of file qgsrelation.cpp.

◆ getReferencedFeature()

QgsFeature QgsRelation::getReferencedFeature ( const QgsFeature feature) const

Creates a request to return the feature on the referenced (parent) layer which is referenced by the provided feature.

Parameters
featureA feature from the referencing (child) layer
Returns
A request the referenced feature

Definition at line 202 of file qgsrelation.cpp.

◆ getReferencedFeatureRequest() [1/2]

QgsFeatureRequest QgsRelation::getReferencedFeatureRequest ( const QgsAttributes attributes) const

Creates a request to return the feature on the referenced (parent) layer which is referenced by the provided feature.

Parameters
attributesAn attribute vector containing the foreign key
Returns
A request the referenced feature
Note
not available in Python bindings

Definition at line 178 of file qgsrelation.cpp.

◆ getReferencedFeatureRequest() [2/2]

QgsFeatureRequest QgsRelation::getReferencedFeatureRequest ( const QgsFeature feature) const

Creates a request to return the feature on the referenced (parent) layer which is referenced by the provided feature.

Parameters
featureA feature from the referencing (child) layer
Returns
A request the referenced feature

Definition at line 197 of file qgsrelation.cpp.

◆ getRelatedFeatures()

QgsFeatureIterator QgsRelation::getRelatedFeatures ( const QgsFeature feature) const

Creates an iterator which returns all the features on the referencing (child) layer which have a foreign key pointing to the provided feature.

Parameters
featureA feature from the referenced (parent) layer
Returns
An iterator with all the referenced features
See also
getRelatedFeaturesRequest()
getRelatedFeaturesFilter()

Definition at line 150 of file qgsrelation.cpp.

◆ getRelatedFeaturesFilter()

QString QgsRelation::getRelatedFeaturesFilter ( const QgsFeature feature) const

Returns a filter expression which returns all the features on the referencing (child) layer which have a foreign key pointing to the provided feature.

Parameters
featureA feature from the referenced (parent) layer
Returns
expression filter string for all the referencing features
Since
QGIS 2.16
See also
getRelatedFeatures()
getRelatedFeaturesRequest()

Definition at line 165 of file qgsrelation.cpp.

◆ getRelatedFeaturesRequest()

QgsFeatureRequest QgsRelation::getRelatedFeaturesRequest ( const QgsFeature feature) const

Creates a request to return all the features on the referencing (child) layer which have a foreign key pointing to the provided feature.

Parameters
featureA feature from the referenced (parent) layer
Returns
A request for all the referencing features
See also
getRelatedFeatures()
getRelatedFeaturesFilter()

Definition at line 155 of file qgsrelation.cpp.

◆ hasEqualDefinition()

bool QgsRelation::hasEqualDefinition ( const QgsRelation other) const

Compares the two QgsRelation, ignoring the name and the ID.

Parameters
otherThe other relation
Returns
true if they are similar
Since
QGIS 3.0

Definition at line 284 of file qgsrelation.cpp.

◆ id()

QString QgsRelation::id ( ) const

A (project-wide) unique id for this relation.

Returns
The id

◆ isValid()

bool QgsRelation::isValid ( ) const

Returns the validity of this relation.

Don't use the information if it's not valid.

Returns
true if the relation is valid

◆ name()

QString QgsRelation::name ( ) const

Returns a human readable name for this relation.

Mostly used as title for the children.

See also
id()
Returns
A name

◆ referencedFields()

QgsAttributeList QgsRelation::referencedFields ( ) const

Returns a list of attributes used to form the referenced fields (most likely primary key) on the referenced (parent) layer.

Returns
A list of attributes

Definition at line 256 of file qgsrelation.cpp.

◆ referencedLayer()

QgsVectorLayer* QgsRelation::referencedLayer ( ) const

Access the referenced (parent) layer.

Returns
referenced layer

◆ referencedLayerId()

QString QgsRelation::referencedLayerId ( ) const

Access the referenced (parent) layer's id.

Returns
The id of the referenced layer

Definition at line 241 of file qgsrelation.cpp.

◆ referencingFields()

QgsAttributeList QgsRelation::referencingFields ( ) const

Returns a list of attributes used to form the referencing fields (foreign key) on the referencing (child) layer.

Returns
A list of attributes

Definition at line 267 of file qgsrelation.cpp.

◆ referencingLayer()

QgsVectorLayer* QgsRelation::referencingLayer ( ) const

Access the referencing (child) layer This is the layer which has the field(s) which point to another layer.

Returns
The referencing layer

◆ referencingLayerId()

QString QgsRelation::referencingLayerId ( ) const

Access the referencing (child) layer's id This is the layer which has the field(s) which point to another layer.

Returns
The id of the referencing layer

Definition at line 231 of file qgsrelation.cpp.

◆ resolveReferencedField()

QString QgsRelation::resolveReferencedField ( const QString &  referencingField) const

Get the referenced field counterpart given a referencing field.

Since
QGIS 3.0

Definition at line 289 of file qgsrelation.cpp.

◆ resolveReferencingField()

QString QgsRelation::resolveReferencingField ( const QString &  referencedField) const

Get the referencing field counterpart given a referenced field.

Since
QGIS 3.0

Definition at line 299 of file qgsrelation.cpp.

◆ setId()

void QgsRelation::setId ( const QString &  id)

Set an id for this relation.

Definition at line 112 of file qgsrelation.cpp.

◆ setName()

void QgsRelation::setName ( const QString &  name)

Set a name for this relation.

Definition at line 119 of file qgsrelation.cpp.

◆ setReferencedLayer()

void QgsRelation::setReferencedLayer ( const QString &  id)

Set the referenced (parent) layer id.

This layer will be searched in the registry.

Definition at line 131 of file qgsrelation.cpp.

◆ setReferencingLayer()

void QgsRelation::setReferencingLayer ( const QString &  id)

Set the referencing (child) layer id.

This layer will be searched in the registry.

Definition at line 124 of file qgsrelation.cpp.

◆ writeXml()

void QgsRelation::writeXml ( QDomNode &  node,
QDomDocument &  doc 
) const

Writes a relation to an XML structure.

Used for saving .qgs projects

Parameters
nodeThe parent node in which the relation will be created
docThe document in which the relation will be saved

Definition at line 93 of file qgsrelation.cpp.

Property Documentation

◆ id

QString QgsRelation::id
readwrite

Definition at line 41 of file qgsrelation.h.

◆ isValid

bool QgsRelation::isValid
read

Definition at line 45 of file qgsrelation.h.

◆ name

QString QgsRelation::name
readwrite

Definition at line 44 of file qgsrelation.h.

◆ referencedLayer

QgsVectorLayer * QgsRelation::referencedLayer
read

Definition at line 43 of file qgsrelation.h.

◆ referencingLayer

QgsVectorLayer * QgsRelation::referencingLayer
read

Definition at line 42 of file qgsrelation.h.


The documentation for this class was generated from the following files: