Validating Pydantic field while setting value

Question

A Pydantic class that has confloat field cannot be initialised if the value provided for it is outside specified range. But when setting this field at later stage (my_object.constrained_field = <big_value>) the new value is not validated.

from pydantic import BaseModel, confloat

class testClass(BaseModel):
    a: confloat(gt=0.0, lt=10.0)

x = testClass(a=2.0) # OK

# x = testClass(a=20.0) # ERROR: outside limits

x.a = 40.0 # OK despite outside limits

print(x.a) # prints '40.0'

Is this possible to validate new value when setting member, so that calling x.a = 40.0 in the example above will raise an exception?

If not -is there any workaround like getting validator method out of the class field?

Samuel Colvin · Accepted Answer · 2020-07-03 14:32:11Z

17

Use validate_assignment on Config.

answered Jul 3, 2020 at 14:32

Samuel Colvin

13.6k7 gold badges64 silver badges78 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

MaciekS Over a year ago

Do you see any reason why validate_assignment is not True by default?

Samuel Colvin Over a year ago

It has a performance impact and I would argue that the majority of cases wouldn't expect it to be on by default.

karuhanga Over a year ago

curious- does this cause root validators to be re-triggered?

Collectives™ on Stack Overflow

Validating Pydantic field while setting value

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related