models.py

from django.contrib.auth.forms import AuthenticationForm
from django.core.exceptions import ObjectDoesNotExist, ValidationError
from django.db import models

class EmailAuthenticationForm(AuthenticationForm):
    def clean_username(self):
        username = self.data['username']
        if '@' in username:
            try:
                username = User.objects.get(email=username).username
            except ObjectDoesNotExist:
                raise ValidationError(
                    self.error_messages['invalid_login'],
                    code='invalid_login',
                    params={'username': self.username_field.verbose_name},
                )
        return username

class Record(models.Model):
    name = models.CharField(max_length=100)


class Lawyer(models.Model):
    name = models.CharField(max_length=30)
    records = models.ManyToManyField(Record)