QGIS API Documentation 3.41.0-Master (3c143d501a8)
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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. | |
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. | |
QString | expression () const |
The expression will be evaluated whenever a default value needs to be calculated for a field. | |
bool | isValid () const |
Returns if this default value should be applied. | |
operator bool () const | |
Checks if a default value is set. | |
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. | |
void | setExpression (const QString &expression) |
The expression will be evaluated whenever a default value needs to be calculated for a field. | |
Properties | |
bool | applyOnUpdate |
QString | expression |
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
@some_variable
to insert a project or application level variable like the username of the one digitizing a feature$length
to insert a derived attribute of a geometryQgsDefaultValue 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.
Definition at line 47 of file qgsdefaultvalue.h.
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explicit |
Create a new default value with the given expression and applyOnUpdate flag.
Definition at line 19 of file qgsdefaultvalue.cpp.
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.
Definition at line 42 of file qgsdefaultvalue.cpp.
QString QgsDefaultValue::expression | ( | ) | const |
The expression will be evaluated whenever a default value needs to be calculated for a field.
Definition at line 32 of file qgsdefaultvalue.cpp.
bool QgsDefaultValue::isValid | ( | ) | const |
Returns if this default value should be applied.
false
if the expression is a null string. Definition at line 52 of file qgsdefaultvalue.cpp.
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explicit |
Checks if a default value is set.
Alias for isValid().
false
if the expression is a null string. Definition at line 57 of file qgsdefaultvalue.cpp.
bool QgsDefaultValue::operator== | ( | const QgsDefaultValue & | other | ) | const |
Definition at line 26 of file qgsdefaultvalue.cpp.
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 47 of file qgsdefaultvalue.cpp.
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 37 of file qgsdefaultvalue.cpp.
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readwrite |
Definition at line 52 of file qgsdefaultvalue.h.
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readwrite |
Definition at line 51 of file qgsdefaultvalue.h.