Class: QgsFieldConstraints

class qgis.core.QgsFieldConstraints

Bases: sip.wrapper

Stores information about constraints which may be present on a field.

QgsFieldConstraints() Constructor for QgsFieldConstraints.

QgsFieldConstraints(a0: QgsFieldConstraints)

Methods

constraintDescription

Returns the descriptive name for the constraint expression.

constraintExpression

Returns the constraint expression for the field, if set.

constraintOrigin

Returns the origin of a field constraint, or ConstraintOriginNotSet if the constraint is not present on this field.

constraintStrength

Returns the strength of a field constraint, or ConstraintStrengthNotSet if the constraint is not present on this field.

constraints

Returns any constraints which are present for the field.

domainName

Returns the associated field domain name, for providers which support field domains.

removeConstraint

Removes a constraint from the field.

setConstraint

Sets a constraint on the field.

setConstraintExpression

Set the constraint expression for the field.

setConstraintStrength

Sets the strength of a constraint.

setDomainName

Sets the associated field domain name, for providers which support field domains.

Attributes

ConstraintExpression

ConstraintNotNull

ConstraintOriginLayer

ConstraintOriginNotSet

ConstraintOriginProvider

ConstraintStrengthHard

ConstraintStrengthNotSet

ConstraintStrengthSoft

ConstraintUnique

staticMetaObject

class Constraint

Bases: int

ConstraintExpression = 4
ConstraintNotNull = 1
class ConstraintOrigin

Bases: int

ConstraintOriginLayer = 2
ConstraintOriginNotSet = 0
ConstraintOriginProvider = 1
class ConstraintStrength

Bases: int

ConstraintStrengthHard = 1
ConstraintStrengthNotSet = 0
ConstraintStrengthSoft = 2
ConstraintUnique = 2
class Constraints
class Constraints(f: QgsFieldConstraints.Constraints | QgsFieldConstraints.Constraint)
class Constraints(a0: QgsFieldConstraints.Constraints)

Bases: sip.wrapper

constraintDescription(self) str

Returns the descriptive name for the constraint expression.

See also

constraints()

Return type:

str

constraintExpression(self) str

Returns the constraint expression for the field, if set.

See also

constraints()

Return type:

str

constraintOrigin(self, constraint: QgsFieldConstraints.Constraint) QgsFieldConstraints.ConstraintOrigin

Returns the origin of a field constraint, or ConstraintOriginNotSet if the constraint is not present on this field.

See also

constraints()

Parameters:

constraint (QgsFieldConstraints.Constraint)

Return type:

QgsFieldConstraints.ConstraintOrigin

constraintStrength(self, constraint: QgsFieldConstraints.Constraint) QgsFieldConstraints.ConstraintStrength

Returns the strength of a field constraint, or ConstraintStrengthNotSet if the constraint is not present on this field.

See also

constraints()

Parameters:

constraint (QgsFieldConstraints.Constraint)

Return type:

QgsFieldConstraints.ConstraintStrength

constraints(self) QgsFieldConstraints.Constraints

Returns any constraints which are present for the field.

See also

setConstraint()

Return type:

QgsFieldConstraints.Constraints

domainName(self) str

Returns the associated field domain name, for providers which support field domains.

See also

setDomainName()

Added in version 3.26.

Return type:

str

removeConstraint(self, constraint: QgsFieldConstraints.Constraint)

Removes a constraint from the field.

See also

setConstraint()

See also

constraints()

Parameters:

constraint (QgsFieldConstraints.Constraint)

setConstraint(self, constraint: QgsFieldConstraints.Constraint, origin: QgsFieldConstraints.ConstraintOrigin = QgsFieldConstraints.ConstraintOriginLayer)

Sets a constraint on the field.

See also

constraints()

Parameters:
setConstraintExpression(self, expression: str | None, description: str | None = '')

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.

See also

constraints()

Parameters:
  • expression (Optional[str])

  • description (Optional[str] = '')

setConstraintStrength(self, constraint: QgsFieldConstraints.Constraint, strength: QgsFieldConstraints.ConstraintStrength)

Sets the strength of a constraint. Constraints default to ConstraintStrengthHard unless explicitly changed.

Parameters:
setDomainName(self, domain: str | None)

Sets the associated field domain name, for providers which support field domains.

See also

domainName()

Added in version 3.26.

Parameters:

domain (Optional[str])

staticMetaObject = <PyQt5.QtCore.QMetaObject object>