How can I programmatically obtain the max_length of a Django model field?

Say I have a Django class something like this:

class Person(models.Model):
    name = models.CharField(max_length=50)
    # ...

How can I p开发者_如何转开发rogramatically obtain the max_length value for the name field?

Person._meta.get_field('name').max_length will give you this value. But having to use _meta suggests this is something you shouldn't do in normal usage.

Edit: as Carl pointed out, this naming is misleading and it does seem quite acceptable to use it: http://www.b-list.org/weblog/2007/nov/04/working-models/

Read more at Django Docs: https://docs.djangoproject.com/en/dev/ref/models/meta/#django.db.models.options.Options.get_field

The question is regarding models, but for people trying to do the same for forms (that's how I ended up in this thread), I think this approach is quite simple and clear:
1. In a template:
{{form.name.field.max_length}}

2. In python code (e.g. in the view)
form.name.field.max_length