QGIS API Documentation  3.9.0-Master (d9ef585e47)
Public Member Functions | Properties | List of all members
QgsDefaultValue Class Reference

The QgsDefaultValue class provides a container for managing client side default values for fields. More...

#include <qgsdefaultvalue.h>

Public Member Functions

 QgsDefaultValue (const QString &expression=QString(), bool applyOnUpdate=false)
 Create a new default value with the given expression and applyOnUpdate flag. More...
 
bool applyOnUpdate () const
 The applyOnUpdate flag determines if this expression should also be applied when a feature is updated or only when it's created. More...
 
QString expression () const
 The expression will be evaluated whenever a default value needs to be calculated for a field. More...
 
bool isValid () const
 Returns if this default value should be applied. More...
 
 operator bool () const SIP_PYTHON_SPECIAL_BOOL(isValid)
 Checks if a default value is set. More...
 
bool operator== (const QgsDefaultValue &other) const
 
void setApplyOnUpdate (bool applyOnUpdate)
 The applyOnUpdate flag determines if this expression should also be applied when a feature is updated or only when it's created. More...
 
void setExpression (const QString &expression)
 The expression will be evaluated whenever a default value needs to be calculated for a field. More...
 

Properties

bool applyOnUpdate
 
QString expression
 

Detailed Description

The QgsDefaultValue class provides a container for managing client side default values for fields.

A QgsDefaultValue consists of an expression string that will be evaluated on the client when a default field value needs to be generated.

Usual values for such an expression are

QgsDefaultValue also has a applyOnUpdate flag which will indicate that a default value should also be applied when a feature is updated. If this is not set, the default value will only be used when a feature is created.

Since
QGIS 3.0

Definition at line 48 of file qgsdefaultvalue.h.

Constructor & Destructor Documentation

◆ QgsDefaultValue()

QgsDefaultValue::QgsDefaultValue ( const QString &  expression = QString(),
bool  applyOnUpdate = false 
)
explicit

Create a new default value with the given expression and applyOnUpdate flag.

See also
QgsVectorLayer::setDefaultValueDefinition

Definition at line 18 of file qgsdefaultvalue.cpp.

Member Function Documentation

◆ applyOnUpdate()

bool QgsDefaultValue::applyOnUpdate ( ) const

The applyOnUpdate flag determines if this expression should also be applied when a feature is updated or only when it's created.

◆ expression()

QString QgsDefaultValue::expression ( ) const

The expression will be evaluated whenever a default value needs to be calculated for a field.

◆ isValid()

bool QgsDefaultValue::isValid ( ) const

Returns if this default value should be applied.

Returns
false if the expression is a null string.

Definition at line 51 of file qgsdefaultvalue.cpp.

◆ operator bool()

QgsDefaultValue::operator bool ( ) const

Checks if a default value is set.

Alias for isValid().

Returns
false if the expression is a null string.

Definition at line 56 of file qgsdefaultvalue.cpp.

◆ operator==()

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

Definition at line 25 of file qgsdefaultvalue.cpp.

◆ setApplyOnUpdate()

void QgsDefaultValue::setApplyOnUpdate ( bool  applyOnUpdate)

The applyOnUpdate flag determines if this expression should also be applied when a feature is updated or only when it's created.

Definition at line 46 of file qgsdefaultvalue.cpp.

◆ setExpression()

void QgsDefaultValue::setExpression ( const QString &  expression)

The expression will be evaluated whenever a default value needs to be calculated for a field.

Definition at line 36 of file qgsdefaultvalue.cpp.

Property Documentation

◆ applyOnUpdate

bool QgsDefaultValue::applyOnUpdate
readwrite

Definition at line 53 of file qgsdefaultvalue.h.

◆ expression

QString QgsDefaultValue::expression
readwrite

Definition at line 52 of file qgsdefaultvalue.h.


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