
from odoo import models, fields, _


class Document_Type(models.Model):

    _name = 'tmc.document_type'

    name = fields.Char(
        string='Document Type'
    )

    abbreviation = fields.Char(
        size=3,
        required=True
    )

    model = fields.Char(
        required=True
    )

    _sql_constraints = [
        ('name_unique',
         'UNIQUE(name)',
         _('Document type name must be unique')),
        ('abbreviation_unique',
         'UNIQUE(abbreviation)',
         _('Document type abbreviation must be unique'))
    ]


from odoo import _, fields, models


class Document_Type(models.Model):

    _name = 'tmc.document_type'

    name = fields.Char(
        string='Document Type'
    )

    abbreviation = fields.Char(
        size=4,
        required=True
    )

    model = fields.Char(
        required=True
    )

    _sql_constraints = [
        ('name_unique',
         'UNIQUE(name)',
         _('Document type name must be unique')),
        ('abbreviation_unique',
         'UNIQUE(abbreviation)',
         _('Document type abbreviation must be unique'))
    ]

Increase size for abbreviation field
[FIX] Increase size for abbreviation field

  
- from odoo import models, fields, _
+ from odoo import _, fields, models
  
  
  class Document_Type(models.Model):
  
      _name = 'tmc.document_type'
  
      name = fields.Char(
          string='Document Type'
      )
  
      abbreviation = fields.Char(
-         size=3,
+         size=4,
          required=True
      )
  
      model = fields.Char(
          required=True
      )
  
      _sql_constraints = [
          ('name_unique',
           'UNIQUE(name)',
           _('Document type name must be unique')),
          ('abbreviation_unique',
           'UNIQUE(abbreviation)',
           _('Document type abbreviation must be unique'))
      ]
  
Increase size for abbreviation field
## Code Before:

from odoo import models, fields, _


class Document_Type(models.Model):

    _name = 'tmc.document_type'

    name = fields.Char(
        string='Document Type'
    )

    abbreviation = fields.Char(
        size=3,
        required=True
    )

    model = fields.Char(
        required=True
    )

    _sql_constraints = [
        ('name_unique',
         'UNIQUE(name)',
         _('Document type name must be unique')),
        ('abbreviation_unique',
         'UNIQUE(abbreviation)',
         _('Document type abbreviation must be unique'))
    ]

## Instruction:
Increase size for abbreviation field
## Code After:

from odoo import _, fields, models


class Document_Type(models.Model):

    _name = 'tmc.document_type'

    name = fields.Char(
        string='Document Type'
    )

    abbreviation = fields.Char(
        size=4,
        required=True
    )

    model = fields.Char(
        required=True
    )

    _sql_constraints = [
        ('name_unique',
         'UNIQUE(name)',
         _('Document type name must be unique')),
        ('abbreviation_unique',
         'UNIQUE(abbreviation)',
         _('Document type abbreviation must be unique'))
    ]
