QGIS API Documentation  3.3.0-Master (1192f94)
qgsfeaturerequest.h
Go to the documentation of this file.
1 /***************************************************************************
2  qgsfeaturerequest.h
3  ---------------------
4  begin : Mai 2012
5  copyright : (C) 2012 by Martin Dobias
6  email : wonder dot sk at gmail dot com
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 #ifndef QGSFEATUREREQUEST_H
16 #define QGSFEATUREREQUEST_H
17 
18 #include "qgis_core.h"
19 #include "qgis_sip.h"
20 #include <QFlags>
21 #include <QList>
22 #include <memory>
23 
24 #include "qgsfeature.h"
25 #include "qgsrectangle.h"
26 #include "qgsexpression.h"
27 #include "qgsexpressioncontext.h"
28 #include "qgssimplifymethod.h"
29 
30 
31 
72 class CORE_EXPORT QgsFeatureRequest
73 {
74  public:
75  enum Flag
76  {
77  NoFlags = 0,
78  NoGeometry = 1,
79  SubsetOfAttributes = 2,
80  ExactIntersect = 4
81  };
82  Q_DECLARE_FLAGS( Flags, Flag )
83 
84 
88  {
92  FilterFids
93  };
94 
97  {
98  GeometryNoCheck = 0,
99  GeometrySkipInvalid = 1,
100  GeometryAbortOnInvalid = 2,
101  };
102 
126  class CORE_EXPORT OrderByClause
127  {
128  public:
129 
138  OrderByClause( const QString &expression, bool ascending = true );
139 
147  OrderByClause( const QString &expression, bool ascending, bool nullsfirst );
148 
157  OrderByClause( const QgsExpression &expression, bool ascending = true );
158 
166  OrderByClause( const QgsExpression &expression, bool ascending, bool nullsfirst );
167 
172  QgsExpression expression() const;
173 
181  bool prepare( QgsExpressionContext *context );
182 
187  bool ascending() const;
188 
192  void setAscending( bool ascending );
193 
198  bool nullsFirst() const;
199 
203  void setNullsFirst( bool nullsFirst );
204 
208  QString dump() const;
209 
210  // friend inline int qHash(const OrderByClause &a) { return qHash(a.mExpression.expression()) ^ qHash(a.mAscending) ^ qHash( a.mNullsFirst); }
211 
212  private:
213  QgsExpression mExpression;
214  bool mAscending;
215  bool mNullsFirst;
216  };
217 
218 
226  class OrderBy : public QList<QgsFeatureRequest::OrderByClause>
227  {
228  public:
229 
233  CORE_EXPORT OrderBy();
234 
238  CORE_EXPORT OrderBy( const QList<QgsFeatureRequest::OrderByClause> &other );
239 
246  QList<QgsFeatureRequest::OrderByClause> CORE_EXPORT list() const;
247 
251  void CORE_EXPORT save( QDomElement &elem ) const;
252 
256  void CORE_EXPORT load( const QDomElement &elem );
257 
261  QSet<QString> CORE_EXPORT usedAttributes() const;
262 
266  QString CORE_EXPORT dump() const;
267  };
268 
272  static const QString ALL_ATTRIBUTES;
273 
277  explicit QgsFeatureRequest( QgsFeatureId fid );
279  explicit QgsFeatureRequest( const QgsFeatureIds &fids );
280 
288  explicit QgsFeatureRequest( const QgsRectangle &rectangle );
289 
291  explicit QgsFeatureRequest( const QgsExpression &expr, const QgsExpressionContext &context = QgsExpressionContext() );
295  QgsFeatureRequest &operator=( const QgsFeatureRequest &rh );
296 
302  FilterType filterType() const { return mFilter; }
303 
313  QgsFeatureRequest &setFilterRect( const QgsRectangle &rectangle );
314 
325  const QgsRectangle &filterRect() const { return mFilterRect; }
326 
328  QgsFeatureRequest &setFilterFid( QgsFeatureId fid );
330  QgsFeatureId filterFid() const { return mFilterFid; }
331 
333  QgsFeatureRequest &setFilterFids( const QgsFeatureIds &fids );
335  const QgsFeatureIds &filterFids() const { return mFilterFids; }
336 
344  QgsFeatureRequest &setInvalidGeometryCheck( InvalidGeometryCheck check );
345 
351  InvalidGeometryCheck invalidGeometryCheck() const { return mInvalidGeometryFilter; }
352 
360 #ifndef SIP_RUN
361  QgsFeatureRequest &setInvalidGeometryCallback( const std::function< void( const QgsFeature & )> &callback );
362 #else
363  QgsFeatureRequest &setInvalidGeometryCallback( SIP_PYCALLABLE / AllowNone / );
364  % MethodCode
365  Py_BEGIN_ALLOW_THREADS
366 
367  sipCpp->setInvalidGeometryCallback( [a0]( const QgsFeature &arg )
368  {
369  SIP_BLOCK_THREADS
370  Py_XDECREF( sipCallMethod( NULL, a0, "D", &arg, sipType_QgsFeature, NULL ) );
371  SIP_UNBLOCK_THREADS
372  } );
373 
374  sipRes = sipCpp;
375 
376  Py_END_ALLOW_THREADS
377  % End
378 #endif
379 
387  std::function< void( const QgsFeature & ) > invalidGeometryCallback() const { return mInvalidGeometryCallback; } SIP_SKIP
388 
395  QgsFeatureRequest &setFilterExpression( const QString &expression );
396 
402  QgsExpression *filterExpression() const { return mFilterExpression.get(); }
403 
410  QgsFeatureRequest &combineFilterExpression( const QString &expression );
411 
418  QgsExpressionContext *expressionContext() { return &mExpressionContext; }
419 
426  QgsFeatureRequest &setExpressionContext( const QgsExpressionContext &context );
427 
436  QgsFeatureRequest &disableFilter() { mFilter = FilterNone; mFilterExpression.reset(); return *this; }
437 
449  QgsFeatureRequest &addOrderBy( const QString &expression, bool ascending = true );
450 
460  QgsFeatureRequest &addOrderBy( const QString &expression, bool ascending, bool nullsfirst );
461 
467  OrderBy orderBy() const;
468 
474  QgsFeatureRequest &setOrderBy( const OrderBy &orderBy );
475 
482  QgsFeatureRequest &setLimit( long limit );
483 
489  long limit() const { return mLimit; }
490 
492  QgsFeatureRequest &setFlags( QgsFeatureRequest::Flags flags );
493  const Flags &flags() const { return mFlags; }
494 
499  QgsFeatureRequest &setSubsetOfAttributes( const QgsAttributeList &attrs );
500 
505  QgsAttributeList subsetOfAttributes() const { return mAttrs; }
506 
508  QgsFeatureRequest &setSubsetOfAttributes( const QStringList &attrNames, const QgsFields &fields );
509 
511  QgsFeatureRequest &setSubsetOfAttributes( const QSet<QString> &attrNames, const QgsFields &fields );
512 
517  QgsFeatureRequest &setSimplifyMethod( const QgsSimplifyMethod &simplifyMethod );
518 
523  const QgsSimplifyMethod &simplifyMethod() const { return mSimplifyMethod; }
524 
533  QgsCoordinateReferenceSystem destinationCrs() const;
534 
542  QgsCoordinateTransformContext transformContext() const;
543 
567  QgsFeatureRequest &setDestinationCrs( const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context );
568 
577 #ifndef SIP_RUN
578  QgsFeatureRequest &setTransformErrorCallback( const std::function< void( const QgsFeature & )> &callback );
579 #else
580  QgsFeatureRequest &setTransformErrorCallback( SIP_PYCALLABLE / AllowNone / );
581  % MethodCode
582  Py_BEGIN_ALLOW_THREADS
583 
584  sipCpp->setTransformErrorCallback( [a0]( const QgsFeature &arg )
585  {
586  SIP_BLOCK_THREADS
587  Py_XDECREF( sipCallMethod( NULL, a0, "D", &arg, sipType_QgsFeature, NULL ) );
588  SIP_UNBLOCK_THREADS
589  } );
590 
591  sipRes = sipCpp;
592 
593  Py_END_ALLOW_THREADS
594  % End
595 #endif
596 
605  std::function< void( const QgsFeature & ) > transformErrorCallback() const { return mTransformErrorCallback; } SIP_SKIP
606 
607 
617  bool acceptFeature( const QgsFeature &feature );
618 
628  Q_DECL_DEPRECATED int connectionTimeout() const SIP_DEPRECATED;
629 
639  Q_DECL_DEPRECATED QgsFeatureRequest &setConnectionTimeout( int connectionTimeout ) SIP_DEPRECATED;
640 
649  int timeout() const;
650 
659  QgsFeatureRequest &setTimeout( int timeout );
660 
673  bool requestMayBeNested() const;
674 
687  QgsFeatureRequest &setRequestMayBeNested( bool requestMayBeNested );
688 
689  protected:
690  FilterType mFilter = FilterNone;
692  QgsFeatureId mFilterFid = -1;
694  std::unique_ptr< QgsExpression > mFilterExpression;
696  Flags mFlags;
699  long mLimit = -1;
701  InvalidGeometryCheck mInvalidGeometryFilter = GeometryNoCheck;
702  std::function< void( const QgsFeature & ) > mInvalidGeometryCallback;
703  std::function< void( const QgsFeature & ) > mTransformErrorCallback;
706  int mTimeout = -1;
707  int mRequestMayBeNested = false;
708 };
709 
710 Q_DECLARE_OPERATORS_FOR_FLAGS( QgsFeatureRequest::Flags )
711 
712 
713 class QgsFeatureIterator;
715 
721 class CORE_EXPORT QgsAbstractFeatureSource
722 {
723  public:
724  virtual ~QgsAbstractFeatureSource();
725 
731  virtual QgsFeatureIterator getFeatures( const QgsFeatureRequest &request = QgsFeatureRequest() ) = 0;
732 
733  protected:
734  void iteratorOpened( QgsAbstractFeatureIterator *it );
735  void iteratorClosed( QgsAbstractFeatureIterator *it );
736 
737  QSet< QgsAbstractFeatureIterator * > mActiveIterators;
738 
739  template<typename> friend class QgsAbstractFeatureIteratorFromSource;
740 };
741 
742 #endif // QGSFEATUREREQUEST_H
Class for parsing and evaluation of expressions (formerly called "search strings").
QgsCoordinateReferenceSystem mCrs
QgsFeatureIds mFilterFids
Wrapper for iterator of features from vector data provider or vector layer.
A rectangle specified with double values.
Definition: qgsrectangle.h:40
long limit() const
Returns the maximum number of features to request, or -1 if no limit set.
Filter using feature ID.
QgsSimplifyMethod mSimplifyMethod
const Flags & flags() const
QSet< QgsFeatureId > QgsFeatureIds
Definition: qgsfeature.h:544
QgsExpressionContext * expressionContext()
Returns the expression context used to evaluate filter expressions.
QgsFeatureId filterFid() const
Gets the feature ID that should be fetched.
FilterType filterType() const
Returns the filter type which is currently set on this request.
Container of fields for a vector layer.
Definition: qgsfields.h:42
const QgsFeatureIds & filterFids() const
Gets feature IDs that should be fetched.
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:62
const QgsCoordinateReferenceSystem & crs
const QgsRectangle & filterRect() const
Returns the rectangle from which features will be taken.
QgsExpressionContext mExpressionContext
InvalidGeometryCheck
Handling of features with invalid geometries.
QgsExpression * filterExpression() const
Returns the filter expression if set.
#define SIP_SKIP
Definition: qgis_sip.h:119
QgsFeatureRequest & disableFilter()
Disables filter conditions.
std::unique_ptr< QgsExpression > mFilterExpression
Internal feature iterator to be implemented within data providers.
QSet< QgsAbstractFeatureIterator *> mActiveIterators
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
This class wraps a request for features to a vector layer (or directly its vector data provider)...
static const QString ALL_ATTRIBUTES
A special attribute that if set matches all attributes.
QgsRectangle mFilterRect
Contains information about the context in which a coordinate transform is executed.
Base class that can be used for any class that is capable of returning features.
#define SIP_DEPRECATED
Definition: qgis_sip.h:99
QgsAttributeList subsetOfAttributes() const
Returns the subset of attributes which at least need to be fetched.
The OrderByClause class represents an order by clause for a QgsFeatureRequest.
No filter is applied.
std::function< void(const QgsFeature &) > mInvalidGeometryCallback
FilterType
Types of filters.
QgsCoordinateTransformContext mTransformContext
std::function< void(const QgsFeature &) > mTransformErrorCallback
QgsAttributeList mAttrs
This class represents a coordinate reference system (CRS).
InvalidGeometryCheck invalidGeometryCheck() const
Returns the invalid geometry checking behavior.
qint64 QgsFeatureId
Definition: qgsfeature.h:37
This class contains information about how to simplify geometries fetched from a QgsFeatureIterator.
QList< int > QgsAttributeList
Definition: qgsfield.h:27
std::function< void(const QgsFeature &) > transformErrorCallback() const
Returns the callback function to use when encountering a transform error when iterating features and ...
const QgsSimplifyMethod & simplifyMethod() const
Gets simplification method for geometries that will be fetched.
std::function< void(const QgsFeature &) > invalidGeometryCallback() const
Returns the callback function to use when encountering an invalid geometry and invalidGeometryCheck()...
Represents a list of OrderByClauses, with the most important first and the least important last...
Helper template that cares of two things: 1.