title: How to set length for python Faker fields
body: <p>I am trying to set up UserFactory using DjangoModelFactory from <a href="https://factoryboy.readthedocs.io/en/latest/" rel="noreferrer">factory_boy</a> and <a href="https://github.com/joke2k/faker" rel="noreferrer">Faker</a>.
  Here is my code.</p>
  
  <pre><code>fake = Faker('uk_UA')
  
  class UserFactory(DjangoModelFactory):
      class Meta:
          model = User
  
      username = fake.user_name
      first_name = fake.first_name_male
      last_name = fake.last_name_male
  
      email = fake.safe_email
  </code></pre>
  
  <p>But when I try to use it I  got error:</p>
  
  <pre><code>    DataError                  Traceback (most recent call last)
  /Users/mero/.virtualenvs/fine-hut/lib/python3.6/site-packages/django/db/backends/utils.py in execute(self, sql, params)
       63             else:
  ---&gt; 64                 return self.cursor.execute(sql, params)
       65
  
  DataError: value too long for type character varying(30)
  </code></pre>
  
  <p>I assume that problem is in too long fields generated by Faker. But I didn't find any way to restrict it's length in python, though found few answers for Ruby Faker.</p>
  
  <p>Is there way to do this in python Faker?
  Or maybe there is some other way to use Faker for generate locale-specific fields?</p>