QGIS API Documentation  3.5.0-Master (cdc3cd1)
Classes | Public Types | Public Member Functions | Static Public Attributes | Protected Attributes | List of all members
QgsFeatureRequest Class Reference

This class wraps a request for features to a vector layer (or directly its vector data provider). More...

#include <qgsfeaturerequest.h>

Classes

class  OrderBy
 Represents a list of OrderByClauses, with the most important first and the least important last. More...
 
class  OrderByClause
 The OrderByClause class represents an order by clause for a QgsFeatureRequest. More...
 

Public Types

enum  FilterType { FilterNone, FilterFid, FilterExpression, FilterFids }
 Types of filters. More...
 
enum  Flag { NoFlags = 0, NoGeometry = 1, SubsetOfAttributes = 2, ExactIntersect = 4 }
 
enum  InvalidGeometryCheck { GeometryNoCheck = 0, GeometrySkipInvalid = 1, GeometryAbortOnInvalid = 2 }
 Handling of features with invalid geometries. More...
 

Public Member Functions

 QgsFeatureRequest ()
 construct a default request: for all features get attributes and geometries More...
 
 QgsFeatureRequest (QgsFeatureId fid)
 construct a request with feature ID filter More...
 
 QgsFeatureRequest (const QgsFeatureIds &fids)
 construct a request with feature ID filter More...
 
 QgsFeatureRequest (const QgsRectangle &rectangle)
 Construct a request with rectangle bounding box filter. More...
 
 QgsFeatureRequest (const QgsExpression &expr, const QgsExpressionContext &context=QgsExpressionContext())
 construct a request with a filter expression More...
 
 QgsFeatureRequest (const QgsFeatureRequest &rh)
 copy constructor More...
 
bool acceptFeature (const QgsFeature &feature)
 Check if a feature is accepted by this requests filter. More...
 
QgsFeatureRequestaddOrderBy (const QString &expression, bool ascending=true)
 Adds a new OrderByClause, appending it as the least important one. More...
 
QgsFeatureRequestaddOrderBy (const QString &expression, bool ascending, bool nullsfirst)
 Adds a new OrderByClause, appending it as the least important one. More...
 
QgsFeatureRequestcombineFilterExpression (const QString &expression)
 Modifies the existing filter expression to add an additional expression filter. More...
 
Q_DECL_DEPRECATED int connectionTimeout () const
 Returns the timeout (in milliseconds) for how long we should wait for a connection if none is available from the pool at this moment. More...
 
QgsCoordinateReferenceSystem destinationCrs () const
 Returns the destination coordinate reference system for feature's geometries, or an invalid QgsCoordinateReferenceSystem if no reprojection will be done and all features will be left with their original geometry. More...
 
QgsFeatureRequestdisableFilter ()
 Disables filter conditions. More...
 
QgsExpressionContextexpressionContext ()
 Returns the expression context used to evaluate filter expressions. More...
 
QgsExpressionfilterExpression () const
 Returns the filter expression if set. More...
 
QgsFeatureId filterFid () const
 Gets the feature ID that should be fetched. More...
 
const QgsFeatureIdsfilterFids () const
 Gets feature IDs that should be fetched. More...
 
const QgsRectanglefilterRect () const
 Returns the rectangle from which features will be taken. More...
 
FilterType filterType () const
 Returns the filter type which is currently set on this request. More...
 
const Flags & flags () const
 
std::function< void(const QgsFeature &) > invalidGeometryCallback () const
 Returns the callback function to use when encountering an invalid geometry and invalidGeometryCheck() is set to GeometryAbortOnInvalid or GeometrySkipInvalid. More...
 
InvalidGeometryCheck invalidGeometryCheck () const
 Returns the invalid geometry checking behavior. More...
 
long limit () const
 Returns the maximum number of features to request, or -1 if no limit set. More...
 
QgsFeatureRequestoperator= (const QgsFeatureRequest &rh)
 Assignment operator. More...
 
OrderBy orderBy () const
 Returns a list of order by clauses specified for this feature request. More...
 
bool requestMayBeNested () const
 In case this request may be run nested within another already running iteration on the same connection, set this to true. More...
 
Q_DECL_DEPRECATED QgsFeatureRequestsetConnectionTimeout (int connectionTimeout)
 Sets the timeout (in milliseconds) for how long we should wait for a connection if none is available from the pool at this moment. More...
 
QgsFeatureRequestsetDestinationCrs (const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context)
 Sets the destination crs for feature's geometries. More...
 
QgsFeatureRequestsetExpressionContext (const QgsExpressionContext &context)
 Sets the expression context used to evaluate filter expressions. More...
 
QgsFeatureRequestsetFilterExpression (const QString &expression)
 Set the filter expression. More...
 
QgsFeatureRequestsetFilterFid (QgsFeatureId fid)
 Sets feature ID that should be fetched. More...
 
QgsFeatureRequestsetFilterFids (const QgsFeatureIds &fids)
 Sets feature IDs that should be fetched. More...
 
QgsFeatureRequestsetFilterRect (const QgsRectangle &rectangle)
 Sets the rectangle from which features will be taken. More...
 
QgsFeatureRequestsetFlags (QgsFeatureRequest::Flags flags)
 Sets flags that affect how features will be fetched. More...
 
QgsFeatureRequestsetInvalidGeometryCallback (const std::function< void(const QgsFeature &)> &callback)
 Sets a callback function to use when encountering an invalid geometry and invalidGeometryCheck() is set to GeometryAbortOnInvalid or GeometrySkipInvalid. More...
 
QgsFeatureRequestsetInvalidGeometryCheck (InvalidGeometryCheck check)
 Sets invalid geometry checking behavior. More...
 
QgsFeatureRequestsetLimit (long limit)
 Set the maximum number of features to request. More...
 
QgsFeatureRequestsetNoAttributes ()
 Set that no attributes will be fetched. More...
 
QgsFeatureRequestsetOrderBy (const OrderBy &orderBy)
 Set a list of order by clauses. More...
 
QgsFeatureRequestsetRequestMayBeNested (bool requestMayBeNested)
 In case this request may be run nested within another already running iteration on the same connection, set this to true. More...
 
QgsFeatureRequestsetSimplifyMethod (const QgsSimplifyMethod &simplifyMethod)
 Set a simplification method for geometries that will be fetched. More...
 
QgsFeatureRequestsetSubsetOfAttributes (const QgsAttributeList &attrs)
 Set a subset of attributes that will be fetched. More...
 
QgsFeatureRequestsetSubsetOfAttributes (const QStringList &attrNames, const QgsFields &fields)
 Sets a subset of attributes by names that will be fetched. More...
 
QgsFeatureRequestsetSubsetOfAttributes (const QSet< QString > &attrNames, const QgsFields &fields)
 Sets a subset of attributes by names that will be fetched. More...
 
QgsFeatureRequestsetTimeout (int timeout)
 Sets the timeout (in milliseconds) for the maximum time we should wait during feature requests before a feature is returned. More...
 
QgsFeatureRequestsetTransformErrorCallback (const std::function< void(const QgsFeature &)> &callback)
 Sets a callback function to use when encountering a transform error when iterating features and a destinationCrs() is set. More...
 
const QgsSimplifyMethodsimplifyMethod () const
 Gets simplification method for geometries that will be fetched. More...
 
QgsAttributeList subsetOfAttributes () const
 Returns the subset of attributes which at least need to be fetched. More...
 
int timeout () const
 Returns the timeout (in milliseconds) for the maximum time we should wait during feature requests before a feature is returned. More...
 
QgsCoordinateTransformContext transformContext () const
 Returns the transform context, for use when a destinationCrs() has been set and reprojection is required. More...
 
std::function< void(const QgsFeature &) > transformErrorCallback () const
 Returns the callback function to use when encountering a transform error when iterating features and a destinationCrs() is set. More...
 

Static Public Attributes

static const QString ALL_ATTRIBUTES = QStringLiteral( "#!allattributes!#" )
 A special attribute that if set matches all attributes. More...
 

Protected Attributes

QgsAttributeList mAttrs
 
QgsCoordinateReferenceSystem mCrs
 
QgsExpressionContext mExpressionContext
 
FilterType mFilter = FilterNone
 
std::unique_ptr< QgsExpressionmFilterExpression
 
QgsFeatureId mFilterFid = -1
 
QgsFeatureIds mFilterFids
 
QgsRectangle mFilterRect
 
Flags mFlags
 
std::function< void(const QgsFeature &) > mInvalidGeometryCallback
 
InvalidGeometryCheck mInvalidGeometryFilter = GeometryNoCheck
 
long mLimit = -1
 
OrderBy mOrderBy
 
int mRequestMayBeNested = false
 
QgsSimplifyMethod mSimplifyMethod
 
int mTimeout = -1
 
QgsCoordinateTransformContext mTransformContext
 
std::function< void(const QgsFeature &) > mTransformErrorCallback
 

Detailed Description

This class wraps a request for features to a vector layer (or directly its vector data provider).

The request may apply a filter to fetch only a particular subset of features. Currently supported filters:

Additionally a spatial rectangle can be set in combination: Only features that intersect given rectangle should be fetched. For the sake of speed, the intersection is often done only using feature's bounding box. There is a flag ExactIntersect that makes sure that only intersecting features will be returned.

For efficiency, it is also possible to tell provider that some data is not required:

The options may be chained, e.g.:

QgsFeatureRequest().setFilterRect(QgsRectangle(0,0,1,1)).setFlags(QgsFeatureRequest.ExactIntersect)

Examples:

# fetch all features:
# fetch all features, only one attribute
QgsFeatureRequest().setSubsetOfAttributes(['myfield'], layer.fields())
# fetch all features, without geometries
QgsFeatureRequest().setFlags(QgsFeatureRequest.NoGeometry)
# fetch only features from particular extent
QgsFeatureRequest().setFilterRect(QgsRectangle(0,0,1,1))
# fetch only one feature
QgsFeatureRequest().setFilterFid(45)

Definition at line 72 of file qgsfeaturerequest.h.

Member Enumeration Documentation

◆ FilterType

Types of filters.

Enumerator
FilterNone 

No filter is applied.

FilterFid 

Filter using feature ID.

FilterExpression 

Filter using expression.

FilterFids 

Filter using feature IDs.

Definition at line 87 of file qgsfeaturerequest.h.

◆ Flag

Enumerator
NoFlags 
NoGeometry 

Geometry is not required. It may still be returned if e.g. required for a filter condition.

SubsetOfAttributes 

Fetch only a subset of attributes (setSubsetOfAttributes sets this flag)

ExactIntersect 

Use exact geometry intersection (slower) instead of bounding boxes.

Definition at line 75 of file qgsfeaturerequest.h.

◆ InvalidGeometryCheck

Handling of features with invalid geometries.

Enumerator
GeometryNoCheck 

No invalid geometry checking.

GeometrySkipInvalid 

Skip any features with invalid geometry. This requires a slow geometry validity check for every feature.

GeometryAbortOnInvalid 

Close iterator on encountering any features with invalid geometry. This requires a slow geometry validity check for every feature.

Definition at line 96 of file qgsfeaturerequest.h.

Constructor & Destructor Documentation

◆ QgsFeatureRequest() [1/6]

QgsFeatureRequest::QgsFeatureRequest ( )

construct a default request: for all features get attributes and geometries

Definition at line 25 of file qgsfeaturerequest.cpp.

◆ QgsFeatureRequest() [2/6]

QgsFeatureRequest::QgsFeatureRequest ( QgsFeatureId  fid)
explicit

construct a request with feature ID filter

Definition at line 30 of file qgsfeaturerequest.cpp.

◆ QgsFeatureRequest() [3/6]

QgsFeatureRequest::QgsFeatureRequest ( const QgsFeatureIds fids)
explicit

construct a request with feature ID filter

Definition at line 37 of file qgsfeaturerequest.cpp.

◆ QgsFeatureRequest() [4/6]

QgsFeatureRequest::QgsFeatureRequest ( const QgsRectangle rectangle)
explicit

Construct a request with rectangle bounding box filter.

When a destination CRS is set using setDestinationCrs(), rectangle is expected to be in the same CRS as the destinationCrs(). Otherwise, rectangle should use the same CRS as the source layer/provider.

Definition at line 45 of file qgsfeaturerequest.cpp.

◆ QgsFeatureRequest() [5/6]

QgsFeatureRequest::QgsFeatureRequest ( const QgsExpression expr,
const QgsExpressionContext context = QgsExpressionContext() 
)
explicit

construct a request with a filter expression

Definition at line 51 of file qgsfeaturerequest.cpp.

◆ QgsFeatureRequest() [6/6]

QgsFeatureRequest::QgsFeatureRequest ( const QgsFeatureRequest rh)

copy constructor

Definition at line 59 of file qgsfeaturerequest.cpp.

Member Function Documentation

◆ acceptFeature()

bool QgsFeatureRequest::acceptFeature ( const QgsFeature feature)

Check if a feature is accepted by this requests filter.

Parameters
featureThe feature which will be tested
Returns
true, if the filter accepts the feature
Since
QGIS 2.1

Definition at line 270 of file qgsfeaturerequest.cpp.

◆ addOrderBy() [1/2]

QgsFeatureRequest & QgsFeatureRequest::addOrderBy ( const QString &  expression,
bool  ascending = true 
)

Adds a new OrderByClause, appending it as the least important one.

Parameters
expressionThe expression to use for ordering
ascendingIf the order should be ascending (1,2,3) or descending (3,2,1) If the order is ascending, by default nulls are last If the order is descending, by default nulls are first
Since
QGIS 2.14

Definition at line 151 of file qgsfeaturerequest.cpp.

◆ addOrderBy() [2/2]

QgsFeatureRequest & QgsFeatureRequest::addOrderBy ( const QString &  expression,
bool  ascending,
bool  nullsfirst 
)

Adds a new OrderByClause, appending it as the least important one.

Parameters
expressionThe expression to use for ordering
ascendingIf the order should be ascending (1,2,3) or descending (3,2,1)
nullsfirstIf true, NULLS are at the beginning, if false, NULLS are at the end
Since
QGIS 2.14

Definition at line 157 of file qgsfeaturerequest.cpp.

◆ combineFilterExpression()

QgsFeatureRequest & QgsFeatureRequest::combineFilterExpression ( const QString &  expression)

Modifies the existing filter expression to add an additional expression filter.

The filter expressions are combined using AND, so only features matching both the existing expression and the additional expression will be returned.

Since
QGIS 2.14

Definition at line 132 of file qgsfeaturerequest.cpp.

◆ connectionTimeout()

int QgsFeatureRequest::connectionTimeout ( ) const

Returns the timeout (in milliseconds) for how long we should wait for a connection if none is available from the pool at this moment.

A negative value (which is set by default) will wait forever.

Note
Only works if the provider supports this option.
Deprecated:
Use timeout() instead.
Since
QGIS 3.0

Definition at line 297 of file qgsfeaturerequest.cpp.

◆ destinationCrs()

QgsCoordinateReferenceSystem QgsFeatureRequest::destinationCrs ( ) const

Returns the destination coordinate reference system for feature's geometries, or an invalid QgsCoordinateReferenceSystem if no reprojection will be done and all features will be left with their original geometry.

See also
setDestinationCrs()
transformContext()
Since
QGIS 3.0

Definition at line 247 of file qgsfeaturerequest.cpp.

◆ disableFilter()

QgsFeatureRequest& QgsFeatureRequest::disableFilter ( )
inline

Disables filter conditions.

The spatial filter (filterRect) will be kept in place.

Returns
The object the method is called on for chaining
Since
QGIS 2.12

Definition at line 436 of file qgsfeaturerequest.h.

◆ expressionContext()

QgsExpressionContext* QgsFeatureRequest::expressionContext ( )
inline

Returns the expression context used to evaluate filter expressions.

See also
setExpressionContext
filterExpression
Since
QGIS 2.12

Definition at line 418 of file qgsfeaturerequest.h.

◆ filterExpression()

QgsExpression* QgsFeatureRequest::filterExpression ( ) const
inline

Returns the filter expression if set.

See also
setFilterExpression
expressionContext

Definition at line 402 of file qgsfeaturerequest.h.

◆ filterFid()

QgsFeatureId QgsFeatureRequest::filterFid ( ) const
inline

Gets the feature ID that should be fetched.

Definition at line 330 of file qgsfeaturerequest.h.

◆ filterFids()

const QgsFeatureIds& QgsFeatureRequest::filterFids ( ) const
inline

Gets feature IDs that should be fetched.

Definition at line 335 of file qgsfeaturerequest.h.

◆ filterRect()

const QgsRectangle& QgsFeatureRequest::filterRect ( ) const
inline

Returns the rectangle from which features will be taken.

If the returned rectangle is null, then no filter rectangle is set.

When a destination CRS is set using setDestinationCrs(), the rectangle will be in the same CRS as the destinationCrs(). Otherwise, the rectangle will use the same CRS as the source layer/provider.

See also
setFilterRect()

Definition at line 325 of file qgsfeaturerequest.h.

◆ filterType()

FilterType QgsFeatureRequest::filterType ( ) const
inline

Returns the filter type which is currently set on this request.

Returns
Filter type

Definition at line 302 of file qgsfeaturerequest.h.

◆ flags()

const Flags& QgsFeatureRequest::flags ( ) const
inline

Definition at line 493 of file qgsfeaturerequest.h.

◆ invalidGeometryCallback()

std::function< void( const QgsFeature & ) > QgsFeatureRequest::invalidGeometryCallback ( ) const
inline

Returns the callback function to use when encountering an invalid geometry and invalidGeometryCheck() is set to GeometryAbortOnInvalid or GeometrySkipInvalid.

Note
not available in Python bindings
See also
setInvalidGeometryCallback()
Since
QGIS 3.0

Definition at line 387 of file qgsfeaturerequest.h.

◆ invalidGeometryCheck()

InvalidGeometryCheck QgsFeatureRequest::invalidGeometryCheck ( ) const
inline

Returns the invalid geometry checking behavior.

See also
setInvalidGeometryCheck()
Since
QGIS 3.0

Definition at line 351 of file qgsfeaturerequest.h.

◆ limit()

long QgsFeatureRequest::limit ( ) const
inline

Returns the maximum number of features to request, or -1 if no limit set.

See also
setLimit
Since
QGIS 2.14

Definition at line 489 of file qgsfeaturerequest.h.

◆ operator=()

QgsFeatureRequest & QgsFeatureRequest::operator= ( const QgsFeatureRequest rh)

Assignment operator.

Definition at line 64 of file qgsfeaturerequest.cpp.

◆ orderBy()

QgsFeatureRequest::OrderBy QgsFeatureRequest::orderBy ( ) const

Returns a list of order by clauses specified for this feature request.

Since
QGIS 2.14

Definition at line 163 of file qgsfeaturerequest.cpp.

◆ requestMayBeNested()

bool QgsFeatureRequest::requestMayBeNested ( ) const

In case this request may be run nested within another already running iteration on the same connection, set this to true.

If this flag is true, this request will be able to make use of "spare" connections to avoid deadlocks.

For example, this should be set on requests that are issued from an expression function.

Since
QGIS 3.4

Definition at line 319 of file qgsfeaturerequest.cpp.

◆ setConnectionTimeout()

QgsFeatureRequest & QgsFeatureRequest::setConnectionTimeout ( int  connectionTimeout)

Sets the timeout (in milliseconds) for how long we should wait for a connection if none is available from the pool at this moment.

A negative value (which is set by default) will wait forever.

Note
Only works if the provider supports this option.
Deprecated:
Use setTimeout() instead.
Since
QGIS 3.0

Definition at line 302 of file qgsfeaturerequest.cpp.

◆ setDestinationCrs()

QgsFeatureRequest & QgsFeatureRequest::setDestinationCrs ( const QgsCoordinateReferenceSystem crs,
const QgsCoordinateTransformContext context 
)

Sets the destination crs for feature's geometries.

If set, all geometries will be reprojected from their original coordinate reference system to this desired reference system. If crs is an invalid QgsCoordinateReferenceSystem then no reprojection will be done and all features will be left with their original geometry.

When a crs is set using setDestinationCrs(), then any filterRect() set on the request is expected to be in the same CRS as the destination CRS.

The feature geometry transformation to the destination CRS is performed after all filter expressions are tested and any virtual fields are calculated. Accordingly, any geometric expressions used in filterExpression() will be performed in the original source CRS. This ensures consistent results are returned regardless of the destination CRS. Similarly, virtual field values will be calculated using the original geometry in the source CRS, so these values are not affected by any destination CRS transform present in the feature request.

See also
destinationCrs()
Since
QGIS 3.0

Definition at line 257 of file qgsfeaturerequest.cpp.

◆ setExpressionContext()

QgsFeatureRequest & QgsFeatureRequest::setExpressionContext ( const QgsExpressionContext context)

Sets the expression context used to evaluate filter expressions.

See also
expressionContext
setFilterExpression
Since
QGIS 2.12

Definition at line 145 of file qgsfeaturerequest.cpp.

◆ setFilterExpression()

QgsFeatureRequest & QgsFeatureRequest::setFilterExpression ( const QString &  expression)

Set the filter expression.

{

See also
QgsExpression}
Parameters
expressionexpression string
See also
filterExpression
setExpressionContext

Definition at line 125 of file qgsfeaturerequest.cpp.

◆ setFilterFid()

QgsFeatureRequest & QgsFeatureRequest::setFilterFid ( QgsFeatureId  fid)

Sets feature ID that should be fetched.

Definition at line 99 of file qgsfeaturerequest.cpp.

◆ setFilterFids()

QgsFeatureRequest & QgsFeatureRequest::setFilterFids ( const QgsFeatureIds fids)

Sets feature IDs that should be fetched.

Definition at line 106 of file qgsfeaturerequest.cpp.

◆ setFilterRect()

QgsFeatureRequest & QgsFeatureRequest::setFilterRect ( const QgsRectangle rectangle)

Sets the rectangle from which features will be taken.

An empty rectangle removes the filter.

When a destination CRS is set using setDestinationCrs(), rectangle is expected to be in the same CRS as the destinationCrs(). Otherwise, rectangle should use the same CRS as the source layer/provider.

See also
filterRect()

Definition at line 93 of file qgsfeaturerequest.cpp.

◆ setFlags()

QgsFeatureRequest & QgsFeatureRequest::setFlags ( QgsFeatureRequest::Flags  flags)

Sets flags that affect how features will be fetched.

Definition at line 180 of file qgsfeaturerequest.cpp.

◆ setInvalidGeometryCallback()

QgsFeatureRequest & QgsFeatureRequest::setInvalidGeometryCallback ( const std::function< void(const QgsFeature &)> &  callback)

Sets a callback function to use when encountering an invalid geometry and invalidGeometryCheck() is set to GeometryAbortOnInvalid or GeometrySkipInvalid.

This function will be called using the feature with invalid geometry as a parameter.

See also
invalidGeometryCallback()
Since
QGIS 3.0

Definition at line 119 of file qgsfeaturerequest.cpp.

◆ setInvalidGeometryCheck()

QgsFeatureRequest & QgsFeatureRequest::setInvalidGeometryCheck ( QgsFeatureRequest::InvalidGeometryCheck  check)

Sets invalid geometry checking behavior.

Note
Invalid geometry checking is not performed when retrieving features directly from a QgsVectorDataProvider.
See also
invalidGeometryCheck()
Since
QGIS 3.0

Definition at line 113 of file qgsfeaturerequest.cpp.

◆ setLimit()

QgsFeatureRequest & QgsFeatureRequest::setLimit ( long  limit)

Set the maximum number of features to request.

Parameters
limitmaximum number of features, or -1 to request all features.
See also
limit()
Since
QGIS 2.14

Definition at line 174 of file qgsfeaturerequest.cpp.

◆ setNoAttributes()

QgsFeatureRequest & QgsFeatureRequest::setNoAttributes ( )

Set that no attributes will be fetched.

To revert a call to setNoAttributes and fetch all or some available attributes, the SubsetOfAttributes flag should be removed from the request.

Since
QGIS 3.4

Definition at line 193 of file qgsfeaturerequest.cpp.

◆ setOrderBy()

QgsFeatureRequest & QgsFeatureRequest::setOrderBy ( const OrderBy orderBy)

Set a list of order by clauses.

Since
QGIS 2.14

Definition at line 168 of file qgsfeaturerequest.cpp.

◆ setRequestMayBeNested()

QgsFeatureRequest & QgsFeatureRequest::setRequestMayBeNested ( bool  requestMayBeNested)

In case this request may be run nested within another already running iteration on the same connection, set this to true.

If this flag is true, this request will be able to make use of "spare" connections to avoid deadlocks.

For example, this should be set on requests that are issued from an expression function.

Since
QGIS 3.4

Definition at line 324 of file qgsfeaturerequest.cpp.

◆ setSimplifyMethod()

QgsFeatureRequest & QgsFeatureRequest::setSimplifyMethod ( const QgsSimplifyMethod simplifyMethod)

Set a simplification method for geometries that will be fetched.

Since
QGIS 2.2

Definition at line 240 of file qgsfeaturerequest.cpp.

◆ setSubsetOfAttributes() [1/3]

QgsFeatureRequest & QgsFeatureRequest::setSubsetOfAttributes ( const QgsAttributeList attrs)

Set a subset of attributes that will be fetched.

An empty attributes list indicates that no attributes will be fetched. To revert a call to setSubsetOfAttributes and fetch all available attributes, the SubsetOfAttributes flag should be removed from the request.

Definition at line 186 of file qgsfeaturerequest.cpp.

◆ setSubsetOfAttributes() [2/3]

QgsFeatureRequest & QgsFeatureRequest::setSubsetOfAttributes ( const QStringList &  attrNames,
const QgsFields fields 
)

Sets a subset of attributes by names that will be fetched.

Definition at line 198 of file qgsfeaturerequest.cpp.

◆ setSubsetOfAttributes() [3/3]

QgsFeatureRequest & QgsFeatureRequest::setSubsetOfAttributes ( const QSet< QString > &  attrNames,
const QgsFields fields 
)

Sets a subset of attributes by names that will be fetched.

Definition at line 219 of file qgsfeaturerequest.cpp.

◆ setTimeout()

QgsFeatureRequest & QgsFeatureRequest::setTimeout ( int  timeout)

Sets the timeout (in milliseconds) for the maximum time we should wait during feature requests before a feature is returned.

A negative value (which is set by default) will wait forever.

Note
Only works if the provider supports this option.
Since
QGIS 3.4

Definition at line 313 of file qgsfeaturerequest.cpp.

◆ setTransformErrorCallback()

QgsFeatureRequest & QgsFeatureRequest::setTransformErrorCallback ( const std::function< void(const QgsFeature &)> &  callback)

Sets a callback function to use when encountering a transform error when iterating features and a destinationCrs() is set.

This function will be called using the feature which encountered the transform error as a parameter.

See also
transformErrorCallback()
setDestinationCrs()
Since
QGIS 3.0

Definition at line 264 of file qgsfeaturerequest.cpp.

◆ simplifyMethod()

const QgsSimplifyMethod& QgsFeatureRequest::simplifyMethod ( ) const
inline

Gets simplification method for geometries that will be fetched.

Since
QGIS 2.2

Definition at line 534 of file qgsfeaturerequest.h.

◆ subsetOfAttributes()

QgsAttributeList QgsFeatureRequest::subsetOfAttributes ( ) const
inline

Returns the subset of attributes which at least need to be fetched.

Returns
A list of attributes to be fetched

Definition at line 516 of file qgsfeaturerequest.h.

◆ timeout()

int QgsFeatureRequest::timeout ( ) const

Returns the timeout (in milliseconds) for the maximum time we should wait during feature requests before a feature is returned.

A negative value (which is set by default) will wait forever.

Note
Only works if the provider supports this option.
Since
QGIS 3.4

Definition at line 308 of file qgsfeaturerequest.cpp.

◆ transformContext()

QgsCoordinateTransformContext QgsFeatureRequest::transformContext ( ) const

Returns the transform context, for use when a destinationCrs() has been set and reprojection is required.

See also
setDestinationCrs()
destinationCrs()
Since
QGIS 3.0

Definition at line 252 of file qgsfeaturerequest.cpp.

◆ transformErrorCallback()

std::function< void( const QgsFeature & ) > QgsFeatureRequest::transformErrorCallback ( ) const
inline

Returns the callback function to use when encountering a transform error when iterating features and a destinationCrs() is set.

Note
not available in Python bindings
See also
setTransformErrorCallback()
destinationCrs()
Since
QGIS 3.0

Definition at line 616 of file qgsfeaturerequest.h.

Member Data Documentation

◆ ALL_ATTRIBUTES

const QString QgsFeatureRequest::ALL_ATTRIBUTES = QStringLiteral( "#!allattributes!#" )
static

A special attribute that if set matches all attributes.

Definition at line 272 of file qgsfeaturerequest.h.

◆ mAttrs

QgsAttributeList QgsFeatureRequest::mAttrs
protected

Definition at line 708 of file qgsfeaturerequest.h.

◆ mCrs

QgsCoordinateReferenceSystem QgsFeatureRequest::mCrs
protected

Definition at line 715 of file qgsfeaturerequest.h.

◆ mExpressionContext

QgsExpressionContext QgsFeatureRequest::mExpressionContext
protected

Definition at line 706 of file qgsfeaturerequest.h.

◆ mFilter

FilterType QgsFeatureRequest::mFilter = FilterNone
protected

Definition at line 701 of file qgsfeaturerequest.h.

◆ mFilterExpression

std::unique_ptr< QgsExpression > QgsFeatureRequest::mFilterExpression
protected

Definition at line 705 of file qgsfeaturerequest.h.

◆ mFilterFid

QgsFeatureId QgsFeatureRequest::mFilterFid = -1
protected

Definition at line 703 of file qgsfeaturerequest.h.

◆ mFilterFids

QgsFeatureIds QgsFeatureRequest::mFilterFids
protected

Definition at line 704 of file qgsfeaturerequest.h.

◆ mFilterRect

QgsRectangle QgsFeatureRequest::mFilterRect
protected

Definition at line 702 of file qgsfeaturerequest.h.

◆ mFlags

Flags QgsFeatureRequest::mFlags
protected

Definition at line 707 of file qgsfeaturerequest.h.

◆ mInvalidGeometryCallback

std::function< void( const QgsFeature & ) > QgsFeatureRequest::mInvalidGeometryCallback
protected

Definition at line 713 of file qgsfeaturerequest.h.

◆ mInvalidGeometryFilter

InvalidGeometryCheck QgsFeatureRequest::mInvalidGeometryFilter = GeometryNoCheck
protected

Definition at line 712 of file qgsfeaturerequest.h.

◆ mLimit

long QgsFeatureRequest::mLimit = -1
protected

Definition at line 710 of file qgsfeaturerequest.h.

◆ mOrderBy

OrderBy QgsFeatureRequest::mOrderBy
protected

Definition at line 711 of file qgsfeaturerequest.h.

◆ mRequestMayBeNested

int QgsFeatureRequest::mRequestMayBeNested = false
protected

Definition at line 718 of file qgsfeaturerequest.h.

◆ mSimplifyMethod

QgsSimplifyMethod QgsFeatureRequest::mSimplifyMethod
protected

Definition at line 709 of file qgsfeaturerequest.h.

◆ mTimeout

int QgsFeatureRequest::mTimeout = -1
protected

Definition at line 717 of file qgsfeaturerequest.h.

◆ mTransformContext

QgsCoordinateTransformContext QgsFeatureRequest::mTransformContext
protected

Definition at line 716 of file qgsfeaturerequest.h.

◆ mTransformErrorCallback

std::function< void( const QgsFeature & ) > QgsFeatureRequest::mTransformErrorCallback
protected

Definition at line 714 of file qgsfeaturerequest.h.


The documentation for this class was generated from the following files: