QGIS API Documentation 3.37.0-Master (c2d15952569)
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qgsrelation.cpp
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1/***************************************************************************
2 qgsrelation.cpp
3 --------------------------------------
4 Date : 29.4.2013
5 Copyright : (C) 2013 Matthias Kuhn
6 Email : matthias at opengis dot ch
7 ***************************************************************************
8 * *
9 * This program is free software; you can redistribute it and/or modify *
10 * it under the terms of the GNU General Public License as published by *
11 * the Free Software Foundation; either version 2 of the License, or *
12 * (at your option) any later version. *
13 * *
14 ***************************************************************************/
15
16#include "qgsrelation.h"
17
18#include "qgsfeatureiterator.h"
19#include "qgslogger.h"
20#include "qgsproject.h"
21#include "qgsvectorlayer.h"
22#include "qgsrelation_p.h"
24#include "qgsrelationmanager.h"
25
26#include <QApplication>
27
29 : d( new QgsRelationPrivate() )
30{
31}
32
34 : d( new QgsRelationPrivate() )
35 , mContext( context )
36{
37}
38
40
42 : d( other.d )
43 , mContext( other.mContext )
44{
45}
46
48{
49 d = other.d;
50 mContext = other.mContext;
51 return *this;
52}
53
54QgsRelation QgsRelation::createFromXml( const QDomNode &node, QgsReadWriteContext &context, const QgsRelationContext &relationContext )
55{
56 QDomElement elem = node.toElement();
57
58 if ( elem.tagName() != QLatin1String( "relation" ) )
59 {
60 QgsLogger::warning( QApplication::translate( "QgsRelation", "Cannot create relation. Unexpected tag '%1'" ).arg( elem.tagName() ) );
61 }
62
63 QgsRelation relation( relationContext );
64
65 QString referencingLayerId = elem.attribute( QStringLiteral( "referencingLayer" ) );
66 QString referencedLayerId = elem.attribute( QStringLiteral( "referencedLayer" ) );
67 QString id = elem.attribute( QStringLiteral( "id" ) );
68 QString name = context.projectTranslator()->translate( QStringLiteral( "project:relations" ), elem.attribute( QStringLiteral( "name" ) ) );
69 QString strength = elem.attribute( QStringLiteral( "strength" ) );
70
71 QMap<QString, QgsMapLayer *> mapLayers = relationContext.project()->mapLayers();
72
75
76 if ( !referencingLayer )
77 {
78 QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which does not exist." ).arg( referencingLayerId ) );
79 }
81 {
82 QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which is not of type VectorLayer." ).arg( referencingLayerId ) );
83 }
84
85 if ( !referencedLayer )
86 {
87 QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which does not exist." ).arg( referencedLayerId ) );
88 }
90 {
91 QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which is not of type VectorLayer." ).arg( referencedLayerId ) );
92 }
93
94 relation.d->mReferencingLayerId = referencingLayerId;
95 relation.d->mReferencingLayer = qobject_cast<QgsVectorLayer *>( referencingLayer );
96 relation.d->mReferencedLayerId = referencedLayerId;
97 relation.d->mReferencedLayer = qobject_cast<QgsVectorLayer *>( referencedLayer );
98 relation.d->mRelationId = id;
99 relation.d->mRelationName = name;
100 relation.d->mRelationStrength = qgsEnumKeyToValue<Qgis::RelationshipStrength>( strength, Qgis::RelationshipStrength::Association );
101
102 QDomNodeList references = elem.elementsByTagName( QStringLiteral( "fieldRef" ) );
103 for ( int i = 0; i < references.size(); ++i )
104 {
105 QDomElement refEl = references.at( i ).toElement();
106
107 QString referencingField = refEl.attribute( QStringLiteral( "referencingField" ) );
108 QString referencedField = refEl.attribute( QStringLiteral( "referencedField" ) );
109
110 relation.addFieldPair( referencingField, referencedField );
111 }
112
113 relation.updateRelationStatus();
114
115 return relation;
116}
117
118void QgsRelation::writeXml( QDomNode &node, QDomDocument &doc ) const
119{
120 QDomElement elem = doc.createElement( QStringLiteral( "relation" ) );
121 elem.setAttribute( QStringLiteral( "id" ), d->mRelationId );
122 elem.setAttribute( QStringLiteral( "name" ), d->mRelationName );
123 elem.setAttribute( QStringLiteral( "referencingLayer" ), d->mReferencingLayerId );
124 elem.setAttribute( QStringLiteral( "referencedLayer" ), d->mReferencedLayerId );
125 elem.setAttribute( QStringLiteral( "strength" ), qgsEnumValueToKey<Qgis::RelationshipStrength>( d->mRelationStrength ) );
126
127 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
128 {
129 QDomElement referenceElem = doc.createElement( QStringLiteral( "fieldRef" ) );
130 referenceElem.setAttribute( QStringLiteral( "referencingField" ), pair.first );
131 referenceElem.setAttribute( QStringLiteral( "referencedField" ), pair.second );
132 elem.appendChild( referenceElem );
133 }
134
135 node.appendChild( elem );
136}
137
138void QgsRelation::setId( const QString &id )
139{
140 d.detach();
141 d->mRelationId = id;
142
144}
145
146void QgsRelation::setName( const QString &name )
147{
148 d.detach();
149 d->mRelationName = name;
150}
151
152
154{
155 d.detach();
156 d->mRelationStrength = strength;
157}
158
159void QgsRelation::setReferencingLayer( const QString &id )
160{
161 d.detach();
162 d->mReferencingLayerId = id;
163
165}
166
167void QgsRelation::setReferencedLayer( const QString &id )
168{
169 d.detach();
170 d->mReferencedLayerId = id;
171
173}
174
175void QgsRelation::addFieldPair( const QString &referencingField, const QString &referencedField )
176{
177 d.detach();
178 d->mFieldPairs << FieldPair( referencingField, referencedField );
180}
181
182void QgsRelation::addFieldPair( const FieldPair &fieldPair )
183{
184 d.detach();
185 d->mFieldPairs << fieldPair;
187}
188
193
195{
196 QString filter = getRelatedFeaturesFilter( feature );
197 QgsDebugMsgLevel( QStringLiteral( "Filter conditions: '%1'" ).arg( filter ), 2 );
198
199 QgsFeatureRequest myRequest;
200 myRequest.setFilterExpression( filter );
201 return myRequest;
202}
203
205{
206 QStringList conditions;
207
208 if ( ! d->mPolymorphicRelationId.isEmpty() )
209 {
211 if ( polyRel.isValid() )
212 {
214 }
215 else
216 {
217 QgsDebugError( "The polymorphic relation is invalid" );
218 conditions << QStringLiteral( " FALSE " );
219 }
220 }
221
222 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
223 {
224 QVariant val( feature.attribute( pair.referencedField() ) );
225 int referencingIdx = referencingLayer()->fields().lookupField( pair.referencingField() );
226 if ( referencingIdx >= 0 )
227 {
228 QVariant::Type fieldType = referencingLayer()->fields().at( referencingIdx ).type();
229 conditions << QgsExpression::createFieldEqualityExpression( pair.referencingField(), val, fieldType );
230 }
231 else
232 {
233 conditions << QgsExpression::createFieldEqualityExpression( pair.referencingField(), val );
234 }
235 }
236
237 return conditions.join( QLatin1String( " AND " ) );
238}
239
241{
242 QStringList conditions;
243
244 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
245 {
246 int referencedIdx = referencedLayer()->fields().lookupField( pair.referencedField() );
247 int referencingIdx = referencingLayer()->fields().lookupField( pair.referencingField() );
248 if ( referencedIdx >= 0 )
249 {
250 QVariant::Type fieldType = referencedLayer()->fields().at( referencedIdx ).type();
251 conditions << QgsExpression::createFieldEqualityExpression( pair.referencedField(), attributes.at( referencingIdx ), fieldType );
252 }
253 else
254 {
255 conditions << QgsExpression::createFieldEqualityExpression( pair.referencedField(), attributes.at( referencingIdx ) );
256 }
257 }
258
259 QgsFeatureRequest myRequest;
260
261 QgsDebugMsgLevel( QStringLiteral( "Filter conditions: '%1'" ).arg( conditions.join( " AND " ) ), 2 );
262
263 myRequest.setFilterExpression( conditions.join( QLatin1String( " AND " ) ) );
264
265 return myRequest;
266}
267
272
274{
276
277 QgsFeature f;
278 d->mReferencedLayer->getFeatures( request ).nextFeature( f );
279 return f;
280}
281
282QString QgsRelation::name() const
283{
284 return d->mRelationName;
285}
286
288{
289 return d->mRelationStrength;
290}
291
292QString QgsRelation::id() const
293{
294 return d->mRelationId;
295}
296
298{
299 if ( !d->mFieldPairs.isEmpty() )
300 {
301 const QgsRelation::FieldPair fieldPair = d->mFieldPairs.at( 0 );
302 d->mRelationId = QStringLiteral( "%1_%2_%3_%4" )
303 .arg( referencingLayerId(),
304 fieldPair.referencingField(),
306 fieldPair.referencedField() );
307 }
309}
310
312{
313 return d->mReferencingLayerId;
314}
315
317{
318 return d->mReferencingLayer;
319}
320
322{
323 return d->mReferencedLayerId;
324}
325
327{
328 return d->mReferencedLayer;
329}
330
331QList<QgsRelation::FieldPair> QgsRelation::fieldPairs() const
332{
333 return d->mFieldPairs;
334}
335
337{
338 QgsAttributeList attrs;
339 attrs.reserve( d->mFieldPairs.size() );
340 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
341 {
342 attrs << d->mReferencedLayer->fields().lookupField( pair.second );
343 }
344 return attrs;
345}
346
348{
349 QgsAttributeList attrs;
350
351 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
352 {
353 attrs << d->mReferencingLayer->fields().lookupField( pair.first );
354 }
355 return attrs;
356
357}
358
360{
361 return d->mValid && !d->mReferencingLayer.isNull() && !d->mReferencedLayer.isNull() && d->mReferencingLayer.data()->isValid() && d->mReferencedLayer.data()->isValid();
362}
363
365{
366 if ( isValid() )
367 return QString();
368
369 if ( d->mReferencingLayer.isNull() )
370 {
371 if ( d->mReferencingLayerId.isEmpty() )
372 return QObject::tr( "Referencing layer not set" );
373 else
374 return QObject::tr( "Referencing layer %1 does not exist" ).arg( d->mReferencingLayerId );
375 }
376 else if ( !d->mReferencingLayer.data()->isValid() )
377 return QObject::tr( "Referencing layer %1 is not valid" ).arg( d->mReferencingLayerId );
378 else if ( d->mReferencedLayer.isNull() )
379 {
380 if ( d->mReferencedLayerId.isEmpty() )
381 return QObject::tr( "Referenced layer not set" );
382 else
383 return QObject::tr( "Referenced layer %1 does not exist" ).arg( d->mReferencedLayerId );
384 }
385 else if ( !d->mReferencedLayer.data()->isValid() )
386 return QObject::tr( "Referenced layer %1 is not valid" ).arg( d->mReferencedLayerId );
387 else
388 return d->mValidationError;
389}
390
392{
393 return d->mReferencedLayerId == other.d->mReferencedLayerId && d->mReferencingLayerId == other.d->mReferencingLayerId && d->mFieldPairs == other.d->mFieldPairs;
394}
395
396QString QgsRelation::resolveReferencedField( const QString &referencingField ) const
397{
398 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
399 {
400 if ( pair.first == referencingField )
401 return pair.second;
402 }
403 return QString();
404}
405
406QString QgsRelation::resolveReferencingField( const QString &referencedField ) const
407{
408 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
409 {
410 if ( pair.second == referencedField )
411 return pair.first;
412 }
413 return QString();
414}
415
417{
418 const QMap<QString, QgsMapLayer *> &mapLayers = mContext.project()->mapLayers();
419
420 d->mReferencingLayer = qobject_cast<QgsVectorLayer *>( mapLayers[d->mReferencingLayerId] );
421 d->mReferencedLayer = qobject_cast<QgsVectorLayer *>( mapLayers[d->mReferencedLayerId] );
422
423 d->mValid = true;
424
425 if ( d->mRelationId.isEmpty() )
426 {
427 QgsDebugError( QStringLiteral( "Invalid relation: no ID" ) );
428 d->mValidationError = QObject::tr( "Relationship has no ID" );
429 d->mValid = false;
430 }
431 else
432 {
433 if ( !d->mReferencedLayer )
434 {
435 QgsDebugMsgLevel( QStringLiteral( "Invalid relation: referenced layer does not exist. ID: %1" ).arg( d->mReferencedLayerId ), 4 );
436 d->mValidationError = QObject::tr( "Referenced layer %1 does not exist" ).arg( d->mReferencedLayerId );
437 d->mValid = false;
438 }
439 else if ( !d->mReferencingLayer )
440 {
441 QgsDebugMsgLevel( QStringLiteral( "Invalid relation: referencing layer does not exist. ID: %2" ).arg( d->mReferencingLayerId ), 4 );
442 d->mValidationError = QObject::tr( "Referencing layer %1 does not exist" ).arg( d->mReferencingLayerId );
443 d->mValid = false;
444 }
445 else
446 {
447 if ( d->mFieldPairs.count() < 1 )
448 {
449 QgsDebugMsgLevel( QStringLiteral( "Invalid relation: no pair of field is specified." ), 4 );
450 d->mValidationError = QObject::tr( "No fields specified for relationship" );
451 d->mValid = false;
452 }
453
454 for ( const FieldPair &pair : std::as_const( d->mFieldPairs ) )
455 {
456 if ( -1 == d->mReferencingLayer->fields().lookupField( pair.first ) )
457 {
458 QgsDebugError( QStringLiteral( "Invalid relation: field %1 does not exist in referencing layer %2" ).arg( pair.first, d->mReferencingLayer->name() ) );
459 d->mValidationError = QObject::tr( "Field %1 does not exist in referencing layer %2" ).arg( pair.first, d->mReferencingLayer->name() );
460 d->mValid = false;
461 break;
462 }
463 else if ( -1 == d->mReferencedLayer->fields().lookupField( pair.second ) )
464 {
465 QgsDebugError( QStringLiteral( "Invalid relation: field %1 does not exist in referenced layer %2" ).arg( pair.second, d->mReferencedLayer->name() ) );
466 d->mValidationError = QObject::tr( "Field %1 does not exist in referenced layer %2" ).arg( pair.second, d->mReferencedLayer->name() );
467 d->mValid = false;
468 break;
469 }
470 }
471 }
472
473 }
474}
475
476void QgsRelation::setPolymorphicRelationId( const QString &polymorphicRelationId )
477{
478 d.detach();
479 d->mPolymorphicRelationId = polymorphicRelationId;
480}
481
483{
484 return d->mPolymorphicRelationId;
485}
486
488{
489 if ( ! mContext.project() || ! mContext.project()->relationManager() )
490 return QgsPolymorphicRelation();
491
492 return mContext.project()->relationManager()->polymorphicRelation( d->mPolymorphicRelationId );
493}
494
496{
497 if ( d->mPolymorphicRelationId.isNull() )
499 else
501}
502
504{
505 switch ( cardinality )
506 {
508 return QObject::tr( "One-to-one" );
510 return QObject::tr( "One-to-many" );
512 return QObject::tr( "Many-to-one" );
514 return QObject::tr( "Many-to-many" );
515 }
517}
518
520{
521 switch ( strength )
522 {
524 return QObject::tr( "Association" );
526 return QObject::tr( "Composition" );
527 }
529}
RelationshipStrength
Relationship strength.
Definition qgis.h:3583
@ Composition
Fix relation, related elements are part of the parent and a parent copy will copy any children or del...
@ Association
Loose relation, related elements are not part of the parent and a parent copy will not copy any child...
RelationshipType
Relationship types.
Definition qgis.h:3569
@ Generated
A generated relation is a child of a polymorphic relation.
@ Normal
A normal relation.
@ Vector
Vector layer.
RelationshipCardinality
Relationship cardinality.
Definition qgis.h:3595
@ ManyToMany
Many to many relationship.
@ ManyToOne
Many to one relationship.
@ OneToOne
One to one relationship.
@ OneToMany
One to many relationship.
A vector of attributes.
static QString createFieldEqualityExpression(const QString &fieldName, const QVariant &value, QVariant::Type fieldType=QVariant::Type::Invalid)
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.
This class wraps a request for features to a vector layer (or directly its vector data provider).
QgsFeatureRequest & setFilterExpression(const QString &expression)
Set the filter expression.
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:56
QgsAttributes attributes
Definition qgsfeature.h:65
QVariant attribute(const QString &name) const
Lookup attribute value by attribute name.
QVariant::Type type
Definition qgsfield.h:60
QgsField at(int i) const
Returns the field at particular index (must be in range 0..N-1).
int lookupField(const QString &fieldName) const
Looks up field's index from the field name.
static void warning(const QString &msg)
Goes to qWarning.
Base class for all map layer types.
Definition qgsmaplayer.h:75
Qgis::LayerType type
Definition qgsmaplayer.h:82
A polymorphic relation consists of the same properties like a normal relation except for the referenc...
QString layerRepresentation(const QgsVectorLayer *layer) const
Returns layer representation as evaluated string.
virtual QString translate(const QString &context, const QString &sourceText, const char *disambiguation=nullptr, int n=-1) const =0
The derived translate() translates with QTranslator and qm file the sourceText.
QgsRelationManager * relationManager
Definition qgsproject.h:117
QMap< QString, QgsMapLayer * > mapLayers(const bool validOnly=false) const
Returns a map of all registered layers by layer ID.
The class is used as a container of context for various read/write operations on other objects.
const QgsProjectTranslator * projectTranslator() const
Returns the project translator.
Context for relations.
const QgsProject * project() const
Gets the associated project.
QgsPolymorphicRelation polymorphicRelation(const QString &polymorphicRelationId) const
Returns the list of relations associated with a polymorphic relation.
Defines a relation between matching fields of the two involved tables of a relation.
Definition qgsrelation.h:67
QString referencingField() const
Gets the name of the referencing (child) field.
Definition qgsrelation.h:77
QString referencedField() const
Gets the name of the referenced (parent) field.
Definition qgsrelation.h:79
QgsFeatureRequest getReferencedFeatureRequest(const QgsAttributes &attributes) const
Creates a request to return the feature on the referenced (parent) layer which is referenced by the p...
QgsAttributeList referencingFields() const
Returns a list of attributes used to form the referencing fields (foreign key) on the referencing (ch...
static QString cardinalityToDisplayString(Qgis::RelationshipCardinality cardinality)
Returns a user-friendly translated string representing a relationship cardinality.
QString name
Definition qgsrelation.h:48
QgsFeature getReferencedFeature(const QgsFeature &feature) const
Creates a request to return the feature on the referenced (parent) layer which is referenced by the p...
void setId(const QString &id)
Set an id for this relation.
QgsFeatureIterator getRelatedFeatures(const QgsFeature &feature) const
Creates an iterator which returns all the features on the referencing (child) layer which have a fore...
QgsRelation()
Default constructor.
void setReferencedLayer(const QString &id)
Set the referenced (parent) layer id.
void setPolymorphicRelationId(const QString &polymorphicRelationId)
Sets the parent polymorphic relation id.
QgsRelation & operator=(const QgsRelation &other)
Copies a relation.
void generateId()
Generate a (project-wide) unique id for this relation.
Q_INVOKABLE QString resolveReferencingField(const QString &referencedField) const
Gets the referencing field counterpart given a referenced field.
bool hasEqualDefinition(const QgsRelation &other) const
Compares the two QgsRelation, ignoring the name and the ID.
static QgsRelation createFromXml(const QDomNode &node, QgsReadWriteContext &context, const QgsRelationContext &relationContext=QgsRelationContext())
Creates a relation from an XML structure.
QString validationError() const
Returns a user-friendly explanation for why the relationship is invalid.
Q_INVOKABLE QString resolveReferencedField(const QString &referencingField) const
Gets the referenced field counterpart given a referencing field.
QString polymorphicRelationId
Definition qgsrelation.h:50
QgsVectorLayer * referencedLayer
Definition qgsrelation.h:47
Qgis::RelationshipType type() const
Returns the type of the relation.
void setStrength(Qgis::RelationshipStrength strength)
Set a strength for this relation.
static QString strengthToDisplayString(Qgis::RelationshipStrength strength)
Returns a user-friendly translated string representing a relationship strength.
QString id
Definition qgsrelation.h:45
void addFieldPair(const QString &referencingField, const QString &referencedField)
Add a field pair which is part of this relation The first element of each pair are the field names of...
void setReferencingLayer(const QString &id)
Set the referencing (child) layer id.
QList< QgsRelation::FieldPair > fieldPairs() const
Returns the field pairs which form this relation The first element of each pair are the field names o...
QgsPolymorphicRelation polymorphicRelation
Definition qgsrelation.h:51
Qgis::RelationshipStrength strength() const
Returns the relation strength as a string.
QgsAttributeList referencedFields() const
Returns a list of attributes used to form the referenced fields (most likely primary key) on the refe...
QgsVectorLayer * referencingLayer
Definition qgsrelation.h:46
QString referencedLayerId() const
Access the referenced (parent) layer's id.
void setName(const QString &name)
Set a name for this relation.
QString referencingLayerId() const
Access the referencing (child) layer's id This is the layer which has the field(s) which point to ano...
void writeXml(QDomNode &node, QDomDocument &doc) const
Writes a relation to an XML structure.
QString getRelatedFeaturesFilter(const QgsFeature &feature) const
Returns a filter expression which returns all the features on the referencing (child) layer which hav...
void updateRelationStatus()
Updates the validity status of this relation.
QgsFeatureRequest getRelatedFeaturesRequest(const QgsFeature &feature) const
Creates a request to return all the features on the referencing (child) layer which have a foreign ke...
Represents a vector layer which manages a vector based data sets.
QgsFeatureIterator getFeatures(const QgsFeatureRequest &request=QgsFeatureRequest()) const FINAL
Queries the layer for features specified in request.
QgsFields fields() const FINAL
Returns the list of fields of this layer.
#define BUILTIN_UNREACHABLE
Definition qgis.h:5790
QList< int > QgsAttributeList
Definition qgsfield.h:27
#define QgsDebugMsgLevel(str, level)
Definition qgslogger.h:39
#define QgsDebugError(str)
Definition qgslogger.h:38