QGIS API Documentation
3.16.0Hannover (43b64b13f3)

Stores information about constraints which may be present on a field. More...
#include <qgsfieldconstraints.h>
Public Types  
enum  Constraint { ConstraintNotNull = 1, ConstraintUnique = 1 << 1, ConstraintExpression = 1 << 2 } 
Constraints which may be present on a field. More...  
enum  ConstraintOrigin { ConstraintOriginNotSet = 0, ConstraintOriginProvider, ConstraintOriginLayer } 
Origin of constraints. More...  
enum  ConstraintStrength { ConstraintStrengthNotSet = 0, ConstraintStrengthHard, ConstraintStrengthSoft } 
Strength of constraints. More...  
Public Member Functions  
QgsFieldConstraints ()  
Constructor for QgsFieldConstraints. More...  
QString  constraintDescription () const 
Returns the descriptive name for the constraint expression. More...  
QString  constraintExpression () const 
Returns the constraint expression for the field, if set. More...  
ConstraintOrigin  constraintOrigin (Constraint constraint) const 
Returns the origin of a field constraint, or ConstraintOriginNotSet if the constraint is not present on this field. More...  
Constraints  constraints () const 
Returns any constraints which are present for the field. More...  
ConstraintStrength  constraintStrength (Constraint constraint) const 
Returns the strength of a field constraint, or ConstraintStrengthNotSet if the constraint is not present on this field. More...  
bool  operator== (const QgsFieldConstraints &other) const 
void  removeConstraint (Constraint constraint) 
Removes a constraint from the field. More...  
void  setConstraint (Constraint constraint, ConstraintOrigin origin=ConstraintOriginLayer) 
Sets a constraint on the field. More...  
void  setConstraintExpression (const QString &expression, const QString &description=QString()) 
Set the constraint expression for the field. More...  
void  setConstraintStrength (Constraint constraint, ConstraintStrength strength) 
Sets the strength of a constraint. More...  
Properties  
Q_GADGET Constraints  constraints 
Stores information about constraints which may be present on a field.
Definition at line 32 of file qgsfieldconstraints.h.
Constraints which may be present on a field.
Enumerator  

ConstraintNotNull  Field may not be null. 
ConstraintUnique  Field must have a unique value. 
ConstraintExpression  Field has an expression constraint set. See constraintExpression(). 
Definition at line 43 of file qgsfieldconstraints.h.
Origin of constraints.
Enumerator  

ConstraintOriginNotSet  Constraint is not set. 
ConstraintOriginProvider  Constraint was set at data provider. 
ConstraintOriginLayer  Constraint was set by layer. 
Definition at line 54 of file qgsfieldconstraints.h.
Strength of constraints.
Definition at line 64 of file qgsfieldconstraints.h.

default 
Constructor for QgsFieldConstraints.

inline 
Returns the descriptive name for the constraint expression.
Definition at line 133 of file qgsfieldconstraints.h.
QString QgsFieldConstraints::constraintExpression  (  )  const 
Returns the constraint expression for the field, if set.
Definition at line 67 of file qgsfieldconstraints.cpp.
QgsFieldConstraints::ConstraintOrigin QgsFieldConstraints::constraintOrigin  (  QgsFieldConstraints::Constraint  constraint  )  const 
Returns the origin of a field constraint, or ConstraintOriginNotSet if the constraint is not present on this field.
Definition at line 19 of file qgsfieldconstraints.cpp.

inline 
Returns any constraints which are present for the field.
Definition at line 81 of file qgsfieldconstraints.h.
QgsFieldConstraints::ConstraintStrength QgsFieldConstraints::constraintStrength  (  QgsFieldConstraints::Constraint  constraint  )  const 
Returns the strength of a field constraint, or ConstraintStrengthNotSet if the constraint is not present on this field.
Definition at line 27 of file qgsfieldconstraints.cpp.
bool QgsFieldConstraints::operator==  (  const QgsFieldConstraints &  other  )  const 
Definition at line 86 of file qgsfieldconstraints.cpp.

inline 
Removes a constraint from the field.
Definition at line 117 of file qgsfieldconstraints.h.
void QgsFieldConstraints::setConstraint  (  QgsFieldConstraints::Constraint  constraint, 
QgsFieldConstraints::ConstraintOrigin  origin = ConstraintOriginLayer 

) 
Sets a constraint on the field.
Definition at line 48 of file qgsfieldconstraints.cpp.
void QgsFieldConstraints::setConstraintExpression  (  const QString &  expression, 
const QString &  description = QString() 

) 
Set the constraint expression for the field.
An optional descriptive name for the constraint can also be set. Setting an empty expression will clear any existing expression constraint.
Definition at line 72 of file qgsfieldconstraints.cpp.
void QgsFieldConstraints::setConstraintStrength  (  QgsFieldConstraints::Constraint  constraint, 
QgsFieldConstraints::ConstraintStrength  strength  
) 
Sets the strength of a constraint.
Constraints default to ConstraintStrengthHard unless explicitly changed.
Definition at line 36 of file qgsfieldconstraints.cpp.

read 
Definition at line 34 of file qgsfieldconstraints.h.