QGIS API Documentation  3.37.0-Master (a5b4d9743e8)
qgsrelation.h
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1 /***************************************************************************
2  qgsrelation.h
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 #ifndef QGSRELATION_H
17 #define QGSRELATION_H
18 
19 #include <QList>
20 #include <QDomNode>
21 #include <QPair>
22 
23 #include "qgis_core.h"
24 #include "qgsreadwritecontext.h"
25 #include "qgsrelationcontext.h"
26 #include "qgsattributes.h"
27 
28 #include "qgis_sip.h"
29 
30 class QgsFeatureIterator;
31 class QgsFeature;
32 class QgsFeatureRequest;
33 class QgsVectorLayer;
34 class QgsRelationPrivate;
36 
41 class CORE_EXPORT QgsRelation
42 {
43  Q_GADGET
44 
45  Q_PROPERTY( QString id READ id WRITE setId )
46  Q_PROPERTY( QgsVectorLayer *referencingLayer READ referencingLayer )
47  Q_PROPERTY( QgsVectorLayer *referencedLayer READ referencedLayer )
48  Q_PROPERTY( QString name READ name WRITE setName )
49  Q_PROPERTY( bool isValid READ isValid )
50  Q_PROPERTY( QString polymorphicRelationId READ polymorphicRelationId WRITE setPolymorphicRelationId )
51  Q_PROPERTY( QgsPolymorphicRelation polymorphicRelation READ polymorphicRelation )
52 
53  public:
54 
55 #ifndef SIP_RUN
56 
66  class FieldPair : public QPair< QString, QString >
67  {
68  public:
70  FieldPair() = default;
71 
73  FieldPair( const QString &referencingField, const QString &referencedField )
74  : QPair< QString, QString >( referencingField, referencedField ) {}
75 
77  QString referencingField() const { return first; }
79  QString referencedField() const { return second; }
80 
81  bool operator==( const FieldPair &other ) const { return first == other.first && second == other.second; }
82  };
83 #endif
84 
88  QgsRelation();
90 
94  QgsRelation( const QgsRelationContext &context );
95 
101  QgsRelation( const QgsRelation &other );
102 
108  QgsRelation &operator=( const QgsRelation &other );
109 
119  static QgsRelation createFromXml( const QDomNode &node, QgsReadWriteContext &context, const QgsRelationContext &relationContext = QgsRelationContext() );
120 
127  void writeXml( QDomNode &node, QDomDocument &doc ) const;
128 
132  void setId( const QString &id );
133 
137  void setName( const QString &name );
138 
142  void setStrength( Qgis::RelationshipStrength strength );
143 
147  void setReferencingLayer( const QString &id );
148 
152  void setReferencedLayer( const QString &id );
153 
162  void addFieldPair( const QString &referencingField, const QString &referencedField );
163 
172  void addFieldPair( const FieldPair &fieldPair ) SIP_SKIP;
173 
184  QgsFeatureIterator getRelatedFeatures( const QgsFeature &feature ) const;
185 
196  QgsFeatureRequest getRelatedFeaturesRequest( const QgsFeature &feature ) const;
197 
206  QString getRelatedFeaturesFilter( const QgsFeature &feature ) const;
207 
216  QgsFeatureRequest getReferencedFeatureRequest( const QgsAttributes &attributes ) const;
217 
226  QgsFeatureRequest getReferencedFeatureRequest( const QgsFeature &feature ) const;
227 
236  QgsFeature getReferencedFeature( const QgsFeature &feature ) const;
237 
245  QString name() const;
246 
252  Qgis::RelationshipStrength strength() const;
253 
259  QString id() const;
260 
264  void generateId();
265 
272  QString referencingLayerId() const;
273 
280  QgsVectorLayer *referencingLayer() const;
281 
287  QString referencedLayerId() const;
288 
294  QgsVectorLayer *referencedLayer() const;
295 
303 #ifndef SIP_RUN
304  QList< QgsRelation::FieldPair > fieldPairs() const;
305 #else
306  QMap< QString, QString > fieldPairs() const;
307  % MethodCode
308  const QList< QgsRelation::FieldPair > &pairs = sipCpp->fieldPairs();
309  sipRes = new QMap< QString, QString >();
310  for ( const QgsRelation::FieldPair &pair : pairs )
311  {
312  sipRes->insert( pair.first, pair.second );
313  }
314  % End
315 #endif
316 
323  QgsAttributeList referencedFields() const;
324 
331  QgsAttributeList referencingFields() const;
332 
341  bool isValid() const;
342 
351  QString validationError() const;
352 
359  bool hasEqualDefinition( const QgsRelation &other ) const;
360 
365  Q_INVOKABLE QString resolveReferencedField( const QString &referencingField ) const;
366 
371  Q_INVOKABLE QString resolveReferencingField( const QString &referencedField ) const;
372 
379  void updateRelationStatus();
380 
385  void setPolymorphicRelationId( const QString &polymorphicRelationId );
386 
391  QString polymorphicRelationId() const;
392 
397  QgsPolymorphicRelation polymorphicRelation() const;
398 
403  Qgis::RelationshipType type() const;
404 
410  static QString cardinalityToDisplayString( Qgis::RelationshipCardinality cardinality );
411 
417  static QString strengthToDisplayString( Qgis::RelationshipStrength strength );
418 
419  private:
420 
421  mutable QExplicitlySharedDataPointer<QgsRelationPrivate> d;
422 
423  QgsRelationContext mContext;
424 };
425 
426 // Register QgsRelation for usage with QVariant
428 
429 #endif // QGSRELATION_H
RelationshipStrength
Relationship strength.
Definition: qgis.h:3611
RelationshipType
Relationship types.
Definition: qgis.h:3597
RelationshipCardinality
Relationship cardinality.
Definition: qgis.h:3623
A vector of attributes.
Definition: qgsattributes.h:59
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).
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition: qgsfeature.h:56
A polymorphic relation consists of the same properties like a normal relation except for the referenc...
The class is used as a container of context for various read/write operations on other objects.
Context for relations.
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
FieldPair(const QString &referencingField, const QString &referencedField)
Constructor which takes two fields.
Definition: qgsrelation.h:73
bool operator==(const FieldPair &other) const
Definition: qgsrelation.h:81
FieldPair()=default
Default constructor: NULL strings.
Represents a vector layer which manages a vector based data sets.
#define SIP_SKIP
Definition: qgis_sip.h:126
Q_DECLARE_METATYPE(QgsDatabaseQueryLogEntry)
QList< int > QgsAttributeList
Definition: qgsfield.h:27