QGIS API Documentation  3.18.1-Zürich (202f1bf7e5)
Public Member Functions | Properties | List of all members
QgsFeature Class Reference

The feature class encapsulates a single feature including its id, geometry and a list of field/values attributes. More...

#include <qgsfeature.h>

Public Member Functions

 QgsFeature (const QgsFeature &rhs)
 Copy constructor. More...
 
 QgsFeature (const QgsFields &fields, QgsFeatureId id=FID_NULL)
 Constructor for QgsFeature. More...
 
 QgsFeature (QgsFeatureId id=FID_NULL)
 Constructor for QgsFeature. More...
 
virtual ~QgsFeature ()
 
int approximateMemoryUsage () const
 Returns the approximate RAM usage of the feature, in bytes. More...
 
QVariant attribute (const QString &name) const
 Lookup attribute value from attribute name. More...
 
QVariant attribute (int fieldIdx) const
 Lookup attribute value from its index. More...
 
int attributeCount () const
 Returns the number of attributes attached to the feature. More...
 
QgsAttributes attributes () const
 Returns the feature's attributes. More...
 
void clearGeometry ()
 Removes any geometry associated with the feature. More...
 
bool deleteAttribute (const QString &name)
 Removes an attribute value by field name. More...
 
void deleteAttribute (int field)
 Deletes an attribute and its value. More...
 
int fieldNameIndex (const QString &fieldName) const
 Utility method to get attribute index from name. More...
 
QgsFields fields () const
 Returns the field map associated with the feature. More...
 
QgsGeometry geometry () const
 Returns the geometry associated with this feature. More...
 
bool hasGeometry () const
 Returns true if the feature has an associated geometry. More...
 
QgsFeatureId id () const
 Gets the feature ID for this feature. More...
 
void initAttributes (int fieldCount)
 Initialize this feature with the given number of fields. More...
 
bool isValid () const
 Returns the validity of this feature. More...
 
 operator QVariant () const
 Allows direct construction of QVariants from features. More...
 
bool operator!= (const QgsFeature &other) const
 Compares two features. More...
 
QgsFeatureoperator= (const QgsFeature &rhs)
 Assignment operator. More...
 
bool operator== (const QgsFeature &other) const
 Compares two features. More...
 
void padAttributes (int count)
 Resizes the attributes attached to this feature by appending the specified count of NULL values to the end of the existing attributes. More...
 
void resizeAttributes (int fieldCount)
 Resizes the attributes attached to this feature to the given number of fields. More...
 
bool setAttribute (const QString &name, const QVariant &value)
 Insert a value into attribute. More...
 
bool setAttribute (int field, const QVariant &attr)
 Set an attribute's value by field index. More...
 
void setAttributes (const QgsAttributes &attrs)
 Sets the feature's attributes. More...
 
void setFields (const QgsFields &fields, bool initAttributes=false)
 Assign a field map with the feature to allow attribute access by attribute name. More...
 
void setGeometry (const QgsGeometry &geometry)
 Set the feature's geometry. More...
 
void setGeometry (std::unique_ptr< QgsAbstractGeometry > geometry)
 Set the feature's geometry. More...
 
void setId (QgsFeatureId id)
 Sets the feature ID for this feature. More...
 
void setValid (bool validity)
 Sets the validity of the feature. More...
 

Properties

QgsAttributes attributes
 
QgsFields fields
 
QgsGeometry geometry
 
Q_GADGET QgsFeatureId id
 

Detailed Description

The feature class encapsulates a single feature including its id, geometry and a list of field/values attributes.

Note
QgsFeature objects are implicitly shared.

Definition at line 55 of file qgsfeature.h.

Constructor & Destructor Documentation

◆ QgsFeature() [1/3]

QgsFeature::QgsFeature ( QgsFeatureId  id = FID_NULL)

Constructor for QgsFeature.

Parameters
idfeature id

Definition at line 39 of file qgsfeature.cpp.

◆ QgsFeature() [2/3]

QgsFeature::QgsFeature ( const QgsFields fields,
QgsFeatureId  id = FID_NULL 
)

Constructor for QgsFeature.

Parameters
fieldsfeature's fields
idfeature id

Definition at line 44 of file qgsfeature.cpp.

◆ QgsFeature() [3/3]

QgsFeature::QgsFeature ( const QgsFeature rhs)

Copy constructor.

Definition at line 51 of file qgsfeature.cpp.

◆ ~QgsFeature()

QgsFeature::~QgsFeature ( )
virtual

Definition at line 82 of file qgsfeature.cpp.

Member Function Documentation

◆ approximateMemoryUsage()

int QgsFeature::approximateMemoryUsage ( ) const

Returns the approximate RAM usage of the feature, in bytes.

This method takes into account the size of variable elements (strings, geometry, ...), but the value returned should be considered as a lower bound estimation.

Since
QGIS 3.16

Definition at line 334 of file qgsfeature.cpp.

◆ attribute() [1/2]

QVariant QgsFeature::attribute ( const QString &  name) const

Lookup attribute value from attribute name.

Field map must be associated using setFields() before this method can be used.

Parameters
nameThe name of the attribute to get
Returns
The value of the attribute (C++: Invalid variant if no such name exists )
Note
For Python: raises a KeyError exception if the field is not found
Alternatively in Python:
feature[name]
See also
setFields

Definition at line 287 of file qgsfeature.cpp.

◆ attribute() [2/2]

QVariant QgsFeature::attribute ( int  fieldIdx) const

Lookup attribute value from its index.

Field map must be associated using setFields() before this method can be used.

Parameters
fieldIdxThe index of the attribute to get
Returns
The value of the attribute (C++: Invalid variant if no such index exists )
Note
For Python: raises a KeyError exception if the field is not found
Alternatively in Python:
feature[fieldIdx]
See also
setFields

Definition at line 279 of file qgsfeature.cpp.

◆ attributeCount()

int QgsFeature::attributeCount ( ) const

Returns the number of attributes attached to the feature.

Since
QGIS 3.18

Definition at line 129 of file qgsfeature.cpp.

◆ attributes()

QgsAttributes QgsFeature::attributes ( ) const

Returns the feature's attributes.

Returns
list of feature's attributes
See also
setAttributes
Note
Alternatively in Python: iterate feature, eg.
[attr for attr in feature]
Since
QGIS 2.9

Definition at line 124 of file qgsfeature.cpp.

◆ clearGeometry()

void QgsFeature::clearGeometry ( )

Removes any geometry associated with the feature.

See also
setGeometry()
hasGeometry()
Since
QGIS 3.0

Definition at line 158 of file qgsfeature.cpp.

◆ deleteAttribute() [1/2]

bool QgsFeature::deleteAttribute ( const QString &  name)

Removes an attribute value by field name.

Field map must be associated using setFields() before this method can be used.

Parameters
nameThe name of the field to delete
Returns
false if attribute name could not be converted to index (C++ only)
Note
For Python: raises a KeyError exception instead of returning false
Alternatively in Python:
del feature[name]
See also
setFields

Definition at line 268 of file qgsfeature.cpp.

◆ deleteAttribute() [2/2]

void QgsFeature::deleteAttribute ( int  field)

Deletes an attribute and its value.

Parameters
fieldthe index of the field
See also
setAttribute
Note
For Python: raises a KeyError exception if the field is not found
Alternatively in Python:
del feature[field]
const QgsField & field
Definition: qgsfield.h:472

Definition at line 97 of file qgsfeature.cpp.

◆ fieldNameIndex()

int QgsFeature::fieldNameIndex ( const QString &  fieldName) const

Utility method to get attribute index from name.

Field map must be associated using setFields() before this method can be used.

Parameters
fieldNamename of field to get attribute index of
Returns
-1 if field does not exist or field map is not associated.
See also
setFields

Definition at line 302 of file qgsfeature.cpp.

◆ fields()

QgsFields QgsFeature::fields ( ) const

Returns the field map associated with the feature.

See also
setFields

Definition at line 179 of file qgsfeature.cpp.

◆ geometry()

QgsGeometry QgsFeature::geometry ( ) const

Returns the geometry associated with this feature.

If the feature has no geometry, an empty QgsGeometry object will be returned.

See also
hasGeometry()
setGeometry()

Definition at line 103 of file qgsfeature.cpp.

◆ hasGeometry()

bool QgsFeature::hasGeometry ( ) const

Returns true if the feature has an associated geometry.

See also
geometry()
Since
QGIS 3.0.

Definition at line 204 of file qgsfeature.cpp.

◆ id()

QgsFeatureId QgsFeature::id ( ) const

Gets the feature ID for this feature.

Returns
feature ID
See also
setId()

Definition at line 92 of file qgsfeature.cpp.

◆ initAttributes()

void QgsFeature::initAttributes ( int  fieldCount)

Initialize this feature with the given number of fields.

Discard any previously set attribute data.

Parameters
fieldCountNumber of fields to initialize
See also
resizeAttributes()

Definition at line 209 of file qgsfeature.cpp.

◆ isValid()

bool QgsFeature::isValid ( ) const

Returns the validity of this feature.

This is normally set by the provider to indicate some problem that makes the feature invalid or to indicate a null feature.

See also
setValid

Definition at line 190 of file qgsfeature.cpp.

◆ operator QVariant()

QgsFeature::operator QVariant ( ) const
inline

Allows direct construction of QVariants from features.

Definition at line 582 of file qgsfeature.h.

◆ operator!=()

bool QgsFeature::operator!= ( const QgsFeature other) const

Compares two features.

Definition at line 77 of file qgsfeature.cpp.

◆ operator=()

QgsFeature & QgsFeature::operator= ( const QgsFeature rhs)

Assignment operator.

Definition at line 56 of file qgsfeature.cpp.

◆ operator==()

bool QgsFeature::operator== ( const QgsFeature other) const

Compares two features.

Definition at line 62 of file qgsfeature.cpp.

◆ padAttributes()

void QgsFeature::padAttributes ( int  count)

Resizes the attributes attached to this feature by appending the specified count of NULL values to the end of the existing attributes.

See also
resizeAttributes()
Since
QGIS 3.18

Definition at line 227 of file qgsfeature.cpp.

◆ resizeAttributes()

void QgsFeature::resizeAttributes ( int  fieldCount)

Resizes the attributes attached to this feature to the given number of fields.

If the new fieldCount is greater than the original number of fields then the additional attributes will be filled with NULL values. All existing attributes will remain unchanged.

If the new fieldCount is less than the original number of fields then the unwanted values will be discarded from the end of the existing attributes.

See also
initAttributes()
padAttributes()
Since
QGIS 3.18

Definition at line 218 of file qgsfeature.cpp.

◆ setAttribute() [1/2]

bool QgsFeature::setAttribute ( const QString &  name,
const QVariant &  value 
)

Insert a value into attribute.

Returns false if attribute name could not be converted to index. Field map must be associated using setFields() before this method can be used. The feature will be valid if it was successful

Parameters
nameThe name of the field to set
valueThe value to set
Returns
false if attribute name could not be converted to index (C++ only)
Note
For Python: raises a KeyError exception instead of returning false
Alternatively in Python:
feature[name] = attr
See also
setFields

Definition at line 256 of file qgsfeature.cpp.

◆ setAttribute() [2/2]

bool QgsFeature::setAttribute ( int  field,
const QVariant &  attr 
)

Set an attribute's value by field index.

The feature will be valid if it was successful.

Parameters
fieldthe index of the field to set
attrthe value of the attribute
Returns
false, if the field index does not exist
Note
For Python: raises a KeyError exception instead of returning false
Alternatively in Python:
feature[field] = attr
See also
setAttributes

Definition at line 236 of file qgsfeature.cpp.

◆ setAttributes()

void QgsFeature::setAttributes ( const QgsAttributes attrs)

Sets the feature's attributes.

The feature will be valid after.

Parameters
attrsattribute list
See also
setAttribute
attributes

Definition at line 134 of file qgsfeature.cpp.

◆ setFields()

void QgsFeature::setFields ( const QgsFields fields,
bool  initAttributes = false 
)

Assign a field map with the feature to allow attribute access by attribute name.

Parameters
fieldsThe attribute fields which this feature holds
initAttributesIf true, attributes are initialized. Clears any data previously assigned. C++: Defaults to false Python: Defaults to true
See also
fields
Since
QGIS 2.9

Definition at line 169 of file qgsfeature.cpp.

◆ setGeometry() [1/2]

void QgsFeature::setGeometry ( const QgsGeometry geometry)

Set the feature's geometry.

The feature will be valid after.

Parameters
geometrynew feature geometry
See also
geometry()
clearGeometry()

Definition at line 144 of file qgsfeature.cpp.

◆ setGeometry() [2/2]

void QgsFeature::setGeometry ( std::unique_ptr< QgsAbstractGeometry geometry)

Set the feature's geometry.

Ownership of the geometry is transferred to the feature. The feature will be made valid after calling this method.

This method is a shortcut for calling:

feature.setGeometry( QgsGeometry( geometry ) )
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:124

Example

# Sets a feature's geometry to a point geometry
feature.setGeometry( QgsPoint( 210, 41 ) )
print(feature.geometry())
# output: <QgsGeometry: Point (210 41)>
# Sets a feature's geometry to a line string
feature.setGeometry( QgsLineString( [ QgsPoint( 210, 41 ), QgsPoint( 301, 55 ) ] ) )
print(feature.geometry())
# output: <QgsGeometry: LineString (210 41, 301 55)>
Line string geometry type, with support for z-dimension and m-values.
Definition: qgslinestring.h:44
Point geometry type, with support for z-dimension and m-values.
Definition: qgspoint.h:38
See also
geometry()
clearGeometry()
Since
QGIS 3.6

Definition at line 151 of file qgsfeature.cpp.

◆ setId()

void QgsFeature::setId ( QgsFeatureId  id)

Sets the feature ID for this feature.

Parameters
idfeature id
See also
id

Definition at line 114 of file qgsfeature.cpp.

◆ setValid()

void QgsFeature::setValid ( bool  validity)

Sets the validity of the feature.

Parameters
validityset to true if feature is valid
See also
isValid

Definition at line 195 of file qgsfeature.cpp.

Property Documentation

◆ attributes

QgsAttributes QgsFeature::attributes
readwrite

Definition at line 62 of file qgsfeature.h.

◆ fields

QgsFields QgsFeature::fields
readwrite

Definition at line 62 of file qgsfeature.h.

◆ geometry

QgsGeometry QgsFeature::geometry
readwrite

Definition at line 62 of file qgsfeature.h.

◆ id

Q_GADGET QgsFeatureId QgsFeature::id
readwrite

Definition at line 62 of file qgsfeature.h.


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