QgsRelationManager Class Reference

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

#include <qgsrelationmanager.h>

Inheritance diagram for QgsRelationManager:

Public Slots
void	updateRelationsStatus ()
	Updates relations status. More...

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

addRelation()

void QgsRelationManager::addRelation

(

const QgsRelation &

relation

)

Add a relation.

Invalid relations are added only if both referencing layer and referenced layer exist.

Parameters

relation

The relation to add.

Definition at line 52 of file qgsrelationmanager.cpp.

changed

void QgsRelationManager::changed ( )

signal

Emitted when relations are added or removed to the manager.

Since

QGIS 2.5

clear()

void QgsRelationManager::clear

(

)

Remove any relation managed by this class.

Definition at line 106 of file qgsrelationmanager.cpp.

discoverRelations()

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 252 of file qgsrelationmanager.cpp.

referencedRelations()

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 151 of file qgsrelationmanager.cpp.

referencingRelations()

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 112 of file qgsrelationmanager.cpp.

relation()

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 87 of file qgsrelationmanager.cpp.

relations()

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 47 of file qgsrelationmanager.cpp.

relationsByName()

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 92 of file qgsrelationmanager.cpp.

relationsLoaded

void QgsRelationManager::relationsLoaded ( )

signal

Emitted when the relations were loaded after reading a project.

removeRelation() [1/2]

void QgsRelationManager::removeRelation

(

const QString &

id

)

Remove a relation.

Parameters

id	The id of the relation to remove.

Definition at line 75 of file qgsrelationmanager.cpp.

removeRelation() [2/2]

void QgsRelationManager::removeRelation

(

const QgsRelation &

relation

)

Remove a relation.

Parameters

relation

The relation to remove.

Definition at line 81 of file qgsrelationmanager.cpp.

setRelations()

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.

updateRelationsStatus

void QgsRelationManager::updateRelationsStatus ( )

slot

Updates relations status.

Definition at line 66 of file qgsrelationmanager.cpp.

---

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

• /tmp/buildd/qgis-3.8.0+99unstable/src/core/qgsrelationmanager.h
• /tmp/buildd/qgis-3.8.0+99unstable/src/core/qgsrelationmanager.cpp