1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
/***************************************************************************
qgsrelation.h
--------------------------------------
Date : 29.4.2013
Copyright : (C) 2013 Matthias Kuhn
Email : matthias dot kuhn at gmx dot ch
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#ifndef QGSRELATION_H
#define QGSRELATION_H
#include <QList>
#include <QDomNode>
#include <QPair>
#include "qgsfield.h"
#include "qgsfeatureiterator.h"
class QgsVectorLayer;
class CORE_EXPORT QgsRelation
{
public:
/**
* Defines a relation between matchin fields of the two involved tables of a relation.
* Often, a relation is only defined by just one FieldPair with the name of the foreign key
* column of the referencing table as first element and the name of the primkary key column
* of the referenced table as the second element.
*
*/
class FieldPair : public QPair< QString, QString >
{
public:
//! Default constructor: NULL strings
FieldPair()
: QPair< QString, QString >() {}
//! Constructor which takes two fields
FieldPair( QString referencingField, QString referencedField )
: QPair< QString, QString >( referencingField, referencedField ) {}
//! Get the name of the referencing field
const QString& referencingField() const { return first; }
//! Get the name of the referenced field
const QString& referencedField() const { return second; }
};
/**
* Default constructor. Creates an invalid relation.
*/
QgsRelation();
/**
* Creates a relation from an XML structure. Used for reading .qgs projects.
*
* @param node The dom node containing the relation information
*
* @return A relation
*/
static QgsRelation createFromXML( const QDomNode& node );
/**
* Writes a relation to an XML structure. Used for saving .qgs projects
*
* @param node The parent node in which the relation will be created
* @param doc The document in which the relation will be saved
*/
void writeXML( QDomNode& node, QDomDocument& doc ) const;
/**
* Set a name for this relation
*
* @param id
*/
void setRelationId( QString id );
/**
* Set a name for this relation
*
* @param name
*/
void setRelationName( QString name );
/**
* Set the referencing layer id. This layer will be searched in the registry.
*
* @param id
*/
void setReferencingLayer( QString id );
/**
* Set the referenced layer id. This layer will be searched in the registry.
*
* @param id
*/
void setReferencedLayer( QString id );
/**
* Add a field pairs which is part of this relation
* The first element of each pair are the field names fo the foreign key.
* The second element of each pair are the field names of the matching primary key.
*
* @param referencingField The field name on the referencing layer (FK)
* @param referencedField The field name on the referenced layer (PK)
*/
void addFieldPair( QString referencingField, QString referencedField );
/**
* Add a field pairs which is part of this relation
* The first element of each pair are the field names fo the foreign key.
* The second element of each pair are the field names of the matching primary key.
*
* @param fieldPair A pair of two strings
* @note not available in python bindings
*/
void addFieldPair( FieldPair fieldPair );
/**
* Creates an iterator which returns all the features on the referencing (child) layer
* which have a foreign key pointing to the provided feature.
*
* @param feature A feature from the referenced (parent) layer
*
* @return An iterator with all the referenced features
*/
QgsFeatureIterator getRelatedFeatures( 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.
*
* @param feature A feature from the referenced (parent) layer
*
* @return An request for all the referenced features
*/
QgsFeatureRequest getRelatedFeaturesRequest( const QgsFeature& feature ) const;
const QString name() const;
/**
* The id
* @return
*/
const QString& id() const;
/**
* Access the referencing (child) layer's id
* This is the layer which has the field(s) which point to another layer
*
* @return The id of the referencing layer
*/
QString referencingLayerId() const;
/**
* Access the referencing (child) layer
* This is the layer which has the field(s) which point to another layer
*
* @return The referencing layer
*/
QgsVectorLayer* referencingLayer() const;
/**
* Access the referenced (parent) layer's id
*
* @return The id of the referenced layer
*/
QString referencedLayerId() const;
/**
* Access the referenced (parent) layer
*
* @return referenced layer
*/
QgsVectorLayer* referencedLayer() const;
/**
* Returns the field pairs which form this relation
* The first element of each pair are the field names fo the foreign key.
* The second element of each pair are the field names of the matching primary key.
*
* @return The fields forming the relation
*/
QList< FieldPair > fieldPairs() const;
/**
* Returns the validity of this relation. Don't use the information if it's not valid.
*
* @return true if the relation is valid
*/
bool isValid() const;
protected:
void updateRelationStatus();
void runChecks();
private:
/** Unique Id */
QString mRelationId;
/** Human redable name*/
QString mRelationName;
/** The child layer */
QString mReferencingLayerId;
/** The child layer */
QgsVectorLayer* mReferencingLayer;
/** The parent layer id */
QString mReferencedLayerId;
/** The parent layer */
QgsVectorLayer* mReferencedLayer;
/** A list of fields which define the relation.
* In most cases there will be only one value, but multiple values
* are supported for composited foreign keys.
* The first field is on the referencing layer, the second on the referenced */
QList< FieldPair > mFieldPairs;
bool mValid;
};
// Register QgsRelation for usage with QVariant
Q_DECLARE_METATYPE( QgsRelation )
#endif // QGSRELATION_H
|
