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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 "qgsapplication.h"
19 #include "qgslogger.h"
20 #include "qgsmaplayerregistry.h"
21 #include "qgsvectorlayer.h"
22 
24  : mReferencingLayer( NULL )
25  , mReferencedLayer( NULL )
26  , mValid( false )
27 {
28 }
29 
31 {
32  QDomElement elem = node.toElement();
33 
34  if ( elem.tagName() != "relation" )
35  {
36  QgsLogger::warning( QApplication::translate( "QgsRelation", "Cannot create relation. Unexpected tag '%1'" ).arg( elem.tagName() ) );
37  }
38 
39  QgsRelation relation;
40 
41  QString referencingLayerId = elem.attribute( "referencingLayer" );
42  QString referencedLayerId = elem.attribute( "referencedLayer" );
43  QString id = elem.attribute( "id" );
44  QString name = elem.attribute( "name" );
45 
47 
50 
51  if ( NULL == referencingLayer )
52  {
53  QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which does not exist." ).arg( referencingLayerId ) );
54  }
55  else if ( QgsMapLayer::VectorLayer != referencingLayer->type() )
56  {
57  QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which is not of type VectorLayer." ).arg( referencingLayerId ) );
58  }
59 
60  if ( NULL == referencedLayer )
61  {
62  QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which does not exist." ).arg( referencedLayerId ) );
63  }
64  else if ( QgsMapLayer::VectorLayer != referencedLayer->type() )
65  {
66  QgsLogger::warning( QApplication::translate( "QgsRelation", "Relation defined for layer '%1' which is not of type VectorLayer." ).arg( referencedLayerId ) );
67  }
68 
69  relation.mReferencingLayerId = referencingLayerId;
70  relation.mReferencingLayer = qobject_cast<QgsVectorLayer*>( referencingLayer );
71  relation.mReferencedLayerId = referencedLayerId;
72  relation.mReferencedLayer = qobject_cast<QgsVectorLayer*>( referencedLayer );
73  relation.mRelationId = id;
74  relation.mRelationName = name;
75 
76  QDomNodeList references = elem.elementsByTagName( "fieldRef" );
77  for ( int i = 0; i < references.size(); ++i )
78  {
79  QDomElement refEl = references.at( i ).toElement();
80 
81  QString referencingField = refEl.attribute( "referencingField" );
82  QString referencedField = refEl.attribute( "referencedField" );
83 
84  relation.addFieldPair( referencingField, referencedField );
85  }
86 
87  relation.updateRelationStatus();
88 
89  return relation;
90 }
91 
92 void QgsRelation::writeXML( QDomNode &node, QDomDocument &doc ) const
93 {
94  QDomElement elem = doc.createElement( "relation" );
95  elem.setAttribute( "id", mRelationId );
96  elem.setAttribute( "name", mRelationName );
97  elem.setAttribute( "referencingLayer", mReferencingLayerId );
98  elem.setAttribute( "referencedLayer", mReferencedLayerId );
99 
100  Q_FOREACH ( FieldPair fields, mFieldPairs )
101  {
102  QDomElement referenceElem = doc.createElement( "fieldRef" );
103  referenceElem.setAttribute( "referencingField", fields.first );
104  referenceElem.setAttribute( "referencedField", fields.second );
105  elem.appendChild( referenceElem );
106  }
107 
108  node.appendChild( elem );
109 }
110 
112 {
113  mRelationId = id;
114 }
115 
117 {
118  mRelationName = name;
119 }
120 
122 {
123  mReferencingLayerId = id;
124 
126 }
127 
129 {
130  mReferencedLayerId = id;
131 
133 }
134 
135 void QgsRelation::addFieldPair( QString referencingField, QString referencedField )
136 {
137  mFieldPairs << FieldPair( referencingField, referencedField );
139 }
140 
142 {
143  mFieldPairs << fieldPair;
145 }
146 
148 {
150 }
151 
153 {
154  QStringList conditions;
155 
156  Q_FOREACH ( const QgsRelation::FieldPair& fieldPair, mFieldPairs )
157  {
158  int referencingIdx = referencingLayer()->fields().indexFromName( fieldPair.referencingField() );
159  QgsField referencingField = referencingLayer()->fields().at( referencingIdx );
160 
161  if ( referencingField.type() == QVariant::String )
162  {
163  // Use quotes
164  conditions << QString( "\"%1\" = '%2'" ).arg( fieldPair.referencingField(), feature.attribute( fieldPair.referencedField() ).toString() );
165  }
166  else
167  {
168  // No quotes
169  conditions << QString( "\"%1\" = %2" ).arg( fieldPair.referencingField(), feature.attribute( fieldPair.referencedField() ).toString() );
170  }
171  }
172 
173  QgsFeatureRequest myRequest;
174 
175  QgsDebugMsg( QString( "Filter conditions: '%1'" ).arg( conditions.join( " AND " ) ) );
176 
177  myRequest.setFilterExpression( conditions.join( " AND " ) );
178 
179  return myRequest;
180 }
181 
183 {
184  QStringList conditions;
185 
186  Q_FOREACH ( const QgsRelation::FieldPair& fieldPair, mFieldPairs )
187  {
188  int referencedIdx = referencedLayer()->fields().indexFromName( fieldPair.referencedField() );
189  int referencingIdx = referencingLayer()->fields().indexFromName( fieldPair.referencingField() );
190 
191  QgsField referencedField = referencedLayer()->fields().at( referencedIdx );
192 
193  if ( referencedField.type() == QVariant::String )
194  {
195  // Use quotes
196  conditions << QString( "\"%1\" = '%2'" ).arg( fieldPair.referencedField(), attributes[referencingIdx].toString() );
197  }
198  else
199  {
200  // No quotes
201  conditions << QString( "\"%1\" = %2" ).arg( fieldPair.referencedField(), attributes[referencingIdx].toString() );
202  }
203  }
204 
205  QgsFeatureRequest myRequest;
206 
207  QgsDebugMsg( QString( "Filter conditions: '%1'" ).arg( conditions.join( " AND " ) ) );
208 
209  myRequest.setFilterExpression( conditions.join( " AND " ) );
210 
211  return myRequest;
212 }
213 
215 {
216  return getReferencedFeatureRequest( feature.attributes() );
217 }
218 
220 {
221  QgsFeatureRequest request = getReferencedFeatureRequest( feature );
222 
223  QgsFeature f;
224  mReferencedLayer->getFeatures( request ).nextFeature( f );
225  return f;
226 }
227 
229 {
230  return mRelationName;
231 }
232 
234 {
235  return mRelationId;
236 }
237 
239 {
240  return mReferencingLayerId;
241 }
242 
244 {
245  return mReferencingLayer;
246 }
247 
249 {
250  return mReferencedLayerId;
251 }
252 
254 {
255  return mReferencedLayer;
256 }
257 
259 {
260  return mFieldPairs;
261 }
262 
264 {
265  return mValid;
266 }
267 
269 {
271 
272  mReferencingLayer = qobject_cast<QgsVectorLayer*>( mapLayers[mReferencingLayerId] );
273  mReferencedLayer = qobject_cast<QgsVectorLayer*>( mapLayers[mReferencedLayerId] );
274 
275  mValid = true;
276 
277  if ( !mReferencedLayer || !mReferencingLayer )
278  {
279  mValid = false;
280  }
281  else
282  {
283  if ( mFieldPairs.count() < 1 )
284  {
285  mValid = false;
286  }
287 
288  Q_FOREACH ( const FieldPair& fieldPair, mFieldPairs )
289  {
290  if ( -1 == mReferencingLayer->fieldNameIndex( fieldPair.first )
291  || -1 == mReferencedLayer->fieldNameIndex( fieldPair.second ) )
292  {
293  mValid = false;
294  }
295  }
296  }
297 }
void setRelationId(QString id)
Set a name for this relation.
Wrapper for iterator of features from vector data provider or vector layer.
bool isValid() const
Returns the validity of this relation.
QDomNodeList elementsByTagName(const QString &tagname) const
Base class for all map layer types.
Definition: qgsmaplayer.h:49
QgsMapLayer::LayerType type() const
Get the type of the layer.
Definition: qgsmaplayer.cpp:93
QDomNode appendChild(const QDomNode &newChild)
QString attribute(const QString &name, const QString &defValue) const
void setRelationName(QString name)
Set a name for this relation.
#define QgsDebugMsg(str)
Definition: qgslogger.h:33
QgsFields fields() const
Returns the list of fields of this layer.
static void warning(const QString &msg)
Goes to qWarning.
Definition: qgslogger.cpp:124
QgsFeatureIterator getFeatures(const QgsFeatureRequest &request=QgsFeatureRequest())
Query the provider for features specified in request.
QgsRelation()
Default constructor.
Definition: qgsrelation.cpp:23
QgsVectorLayer * referencedLayer() const
Access the referenced (parent) layer.
static QgsRelation createFromXML(const QDomNode &node)
Creates a relation from an XML structure.
Definition: qgsrelation.cpp:30
void setReferencingLayer(QString id)
Set the referencing layer id.
QString join(const QString &separator) const
QString name() const
Returns a human readable name for this relation.
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:162
QString referencingLayerId() const
Access the referencing (child) layer's id This is the layer which has the field(s) which point to ano...
QgsFeatureRequest getReferencedFeatureRequest(const QgsAttributes &attributes) const
Creates a request to return the feature on the referenced (parent) layer which is referenced by the p...
QString id() const
A (project-wide) unique id for this relation.
void writeXML(QDomNode &node, QDomDocument &doc) const
Writes a relation to an XML structure.
Definition: qgsrelation.cpp:92
QDomElement toElement() const
QgsFeatureRequest & setFilterExpression(const QString &expression)
Set the filter expression.
void setReferencedLayer(QString id)
Set the referenced layer id.
Defines a relation between matchin fields of the two involved tables of a relation.
Definition: qgsrelation.h:38
QgsFeature getReferencedFeature(const QgsFeature &feature) const
Creates a request to return the feature on the referenced (parent) layer which is referenced by the p...
QgsAttributes attributes() const
Returns the feature's attributes.
Definition: qgsfeature.cpp:90
void setAttribute(const QString &name, const QString &value)
QgsVectorLayer * referencingLayer() const
Access the referencing (child) layer This is the layer which has the field(s) which point to another ...
This class wraps a request for features to a vector layer (or directly its vector data provider)...
Encapsulate a field in an attribute table or data source.
Definition: qgsfield.h:40
QgsFeatureRequest getRelatedFeaturesRequest(const QgsFeature &feature) const
Creates a request to return all the features on the referencing (child) layer which have a foreign ke...
const QgsField & at(int i) const
Get field at particular index (must be in range 0..N-1)
Definition: qgsfield.cpp:305
QString referencedLayerId() const
Access the referenced (parent) layer's id.
int indexFromName(const QString &name) const
Look up field's index from name. Returns -1 on error.
Definition: qgsfield.cpp:338
const QString & referencingField() const
Get the name of the referencing field.
Definition: qgsrelation.h:50
static QgsMapLayerRegistry * instance()
Returns the instance pointer, creating the object on the first call.
QVariant attribute(const QString &name) const
Lookup attribute value from attribute name.
Definition: qgsfeature.cpp:236
QgsFeatureIterator getRelatedFeatures(const QgsFeature &feature) const
Creates an iterator which returns all the features on the referencing (child) layer which have a fore...
QString translate(const char *context, const char *sourceText, const char *disambiguation, Encoding encoding)
const QMap< QString, QgsMapLayer * > & mapLayers()
Retrieve the mapLayers collection (mainly intended for use by projection)
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 f...
QList< FieldPair > fieldPairs() const
Returns the field pairs which form this relation The first element of each pair are the field names f...
QString tagName() const
int size() const
QDomElement createElement(const QString &tagName)
bool nextFeature(QgsFeature &f)
A vector of attributes.
Definition: qgsfeature.h:109
Represents a vector layer which manages a vector based data sets.
int fieldNameIndex(const QString &fieldName) const
Returns the index of a field name or -1 if the field does not exist.
QString arg(qlonglong a, int fieldWidth, int base, const QChar &fillChar) const
const QString & referencedField() const
Get the name of the referenced field.
Definition: qgsrelation.h:52
void updateRelationStatus()
QDomNode at(int index) const
QVariant::Type type() const
Gets variant type of the field as it will be retrieved from data source.
Definition: qgsfield.cpp:75