Get a tuple value in a tuple by index

Question

for a Django Model i needed an extra field to set a special month. This was done with the choices attribute an a tuple set:

class Timeline(models.Model):

    MONTHS = (
        (1, _("January")),
        (2, _("February")),
        (3, _("March")),
        (4, _("April")),
        (5, _("May")),
        (6, _("June")),
        (7, _("July")),
        (8, _("August")),
        (9, _("September")),
        (10, _("October")),
        (11, _("November")),
        (12, _("December")),
    )

    tldate_mth = models.IntegerField(_("Month"), choices=MONTHS, default=1)

In admin section this works fantastic. Now i want to output the month in my template:

 # ...
 def to_string(self):
    return "%s (%s / %d)" % (self.title, self.MONTHS.index(self.tldate_mth), self.tldate_yr)

But then i got the message "tuple.index(x): x not in tuple". What did i wrong?

Answer 1

Django provides you a shortcut do to this: self.get_tldate_mth_display() .

(The reason your code failed is that that isn't at all what .index() does; you should just do self.MONTHS[self.tldate_mth-1][1] ; but, as I say, there's no need to do that when there's a built-in way already.)

Answer 2

Try this:

def to_string(self):
    return "%s (%s / %d)" % (self.title, [month[0] for month in self.MONTHS].index(self.tldate_mth), self.tldate_yr)

Django stores only the first value of the tuple (values 1-12 in this case) for choices field.