Should __unicode__ be used when returning purely numerical values?

[sampablokuper]

​http://docs.djangoproject.com/en/dev/intro/tutorial01/#playing-with-the-api says, "It's important to add __unicode__() methods to your models, not only for your own sanity when dealing with the interactive prompt, but also because objects' representations are used throughout Django's automatically-generated admin."

However, if I have a class like the following:

class C19Year(models.Model):
    value = IntegerRangeField(min_value=1800, max_value=1899)
    def __unicode__(self):
            return self.value

(where IntegerRangeField is as given ​here), I receive the following TemplateSyntaxError in the admin:

Caught an exception while rendering: coercing to Unicode: need string or buffer, int found

So, evidently the manual ought to explain that __unicode__ shouldn't be used when returning purely numerical values, or that such values ought to be converted to strings. (Of these two solutions, I'm not sure which is best.)

[sampablokuper]

For example,

class C19Year(models.Model):
    value = IntegerRangeField(min_value=1800, max_value=1899)
    def __unicode__(self):
            return str(self.value)

works, but is this the best solution? Whatever the best solution is, should go into the docs as recommended practice.

[mrts]

There's nothing Django-specific in __unicode__ and it's sufficiently documented (answering your question among other things) in general
​Python docs:

Called to implement unicode() builtin; should return a Unicode object. When this method is not defined, string conversion is attempted, and the result of string conversion is converted to Unicode using the system default encoding.