This class manages a set of relations between layers. More...

#include <qgsrelationmanager.h>

Inheritance diagram for QgsRelationManager:

Signals
void	changed ()
	Emitted when relations are added or removed to the manager. More...

void	relationsLoaded ()
	This signal is emitted when the relations were loaded after reading a project. More...

Public Member Functions
	QgsRelationManager (QgsProject *project=nullptr)
	Constructor for QgsRelationManager. More...

void	addRelation (const QgsRelation &relation)
	Add a relation. More...

void	clear ()
	Remove any relation managed by this class. More...

QList< QgsRelation >	referencedRelations (QgsVectorLayer *layer=nullptr) const
	Gets all relations where this layer is the referenced part (i.e. More...

QList< QgsRelation >	referencingRelations (const QgsVectorLayer *layer=nullptr, int fieldIdx=-2) const
	Gets all relations where the specified layer (and field) is the referencing part (i.e. More...

Q_INVOKABLE QgsRelation	relation (const QString &id) const
	Gets access to a relation by its id. More...

QMap< QString, QgsRelation >	relations () const
	Gets access to the relations managed by this class. More...

QList< QgsRelation >	relationsByName (const QString &name) const
	Returns a list of relations with matching names. More...

void	removeRelation (const QString &id)
	Remove a relation. More...

void	removeRelation (const QgsRelation &relation)
	Remove a relation. More...

void	setRelations (const QList< QgsRelation > &relations)
	Will set the specified relations and remove any relation currently set. More...

Static Public Member Functions
static QList< QgsRelation >	discoverRelations (const QList< QgsRelation > &existingRelations, const QList< QgsVectorLayer * > &layers)
	Discover all the relations available from the current layers. More...

Detailed Description

This class manages a set of relations between layers.

Definition at line 34 of file qgsrelationmanager.h.

Constructor & Destructor Documentation

QgsRelationManager::QgsRelationManager ( QgsProject * project = nullptr )

explicit

Constructor for QgsRelationManager.

Parameters

project associated project (used to notify project of changes)

Definition at line 24 of file qgsrelationmanager.cpp.

Member Function Documentation

void QgsRelationManager::addRelation ( const QgsRelation & relation )

Add a relation.

Parameters

relation The relation to add.

Definition at line 51 of file qgsrelationmanager.cpp.

void QgsRelationManager::changed ( )

signal

Emitted when relations are added or removed to the manager.

Since: QGIS 2.5

void QgsRelationManager::clear ( )

Remove any relation managed by this class.

Definition at line 93 of file qgsrelationmanager.cpp.

QList< QgsRelation > QgsRelationManager::discoverRelations	(	const QList< QgsRelation > &	existingRelations,
		const QList< QgsVectorLayer * > &	layers
	)

static

Discover all the relations available from the current layers.

Parameters

existingRelations	the existing relations to filter them out
layers	the current layers

Returns: the list of discovered relations

Since: QGIS 3.0

Definition at line 233 of file qgsrelationmanager.cpp.

QList< QgsRelation > QgsRelationManager::referencedRelations ( QgsVectorLayer * layer = nullptr ) const

Gets all relations where this layer is the referenced part (i.e.

the parent table with the primary key being referenced from another layer).

Parameters

layer The layer which should be searched for.

Returns: A list of relations where the specified layer is the referenced part.

Definition at line 136 of file qgsrelationmanager.cpp.

QList< QgsRelation > QgsRelationManager::referencingRelations	(	const QgsVectorLayer *	layer = `nullptr`,
		int	fieldIdx = `-2`
	)		const

Gets all relations where the specified layer (and field) is the referencing part (i.e.

the child table with the foreign key).

Parameters

layer	The layer which should be searched for.
fieldIdx	The field which should be part of the foreign key. If not set will return all relations.

Returns: A list of relations matching the given layer and fieldIdx.

Definition at line 99 of file qgsrelationmanager.cpp.

QgsRelation QgsRelationManager::relation ( const QString & id ) const

Gets access to a relation by its id.

Parameters

id	The id to search for

Returns: A relation. Invalid if not found.

See also: relationsByName()

Definition at line 75 of file qgsrelationmanager.cpp.

QMap< QString, QgsRelation > QgsRelationManager::relations ( ) const

Gets access to the relations managed by this class.

Returns: A QMap where the key is the relation id, the value the relation object.

Definition at line 46 of file qgsrelationmanager.cpp.

QList< QgsRelation > QgsRelationManager::relationsByName ( const QString & name ) const

Returns a list of relations with matching names.

Parameters

name	relation name to search for. Searching is case insensitive.

Returns: a list of matching relations

See also: relation()

Since: QGIS 2.16

Definition at line 80 of file qgsrelationmanager.cpp.

void QgsRelationManager::relationsLoaded ( )

signal

This signal is emitted when the relations were loaded after reading a project.

void QgsRelationManager::removeRelation ( const QString & id )

Remove a relation.

Parameters

id	The id of the relation to remove.

Definition at line 63 of file qgsrelationmanager.cpp.

void QgsRelationManager::removeRelation ( const QgsRelation & relation )

Remove a relation.

Parameters

relation The relation to remove.

Definition at line 69 of file qgsrelationmanager.cpp.

void QgsRelationManager::setRelations ( const QList< QgsRelation > & relations )

Will set the specified relations and remove any relation currently set.

Parameters

relations A list of relations to set.

Definition at line 36 of file qgsrelationmanager.cpp.

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

/build/qgis-3.4.15+24xenial/src/core/qgsrelationmanager.h
/build/qgis-3.4.15+24xenial/src/core/qgsrelationmanager.cpp

Signals

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation