How to set character limit in Text field ..?

Question

My py and xml files code show below and i want to set 300 character limit for text field so what kind of changes needed in this code ?

.py Code :

description': fields.text('Description', required=True)

.Xml Code :

<field name="description"/>

Answer 1

Here I am explaining how to use constraints effectively.

@api.constrains('your_field')
@api.one
def _check_your_field(self):

    if len(self.your_field) > 300:
        raise ValidationError('Number of characters must not exceed 300')

Don't forget to import

from odoo.exceptions import UserError, ValidationError