Django: Filtering datetime field by *only* the year value?

Question

Hi folks,

I'm trying to spit out a django page which lists all entries by the year they were created. So, for example:

2010:

• Note 4

• Note 5

• Note 6

2009:

• Note 1

• Note 2

• Note 3

It's proving more difficult than I would have expected. The model from which the data comes is below:

class Note(models.Model):
    business = models.ForeignKey(Business)
    note = models.TextField()
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    class Meta:
        db_table = 'client_note'

    @property
    def note_year(self):
        return self.created.strftime('%Y')

    def __unicode__(self):
        return '%s' % self.note

I've tried a few different ways, but seem to run into hurdles down every path. I'm guessing an effective 'group by' method would do the trick (PostGres DB Backend), but I can't seem to find any Django functionality that supports it. I tried getting individual years from the database but I struggled to find a way of filtering datetime fields by just the year value. Finally, I tried adding the note_year @property but because it's derived, I can't filter those values.

Any suggestions for an elegant way to do this? I figure it should be pretty straightforward, but I'm having a heckuva time with it. Any ideas much appreciated.

Answer 1

You can use django.views.generic.date_based.archive_year or use year field lookup.

Answer 2

Either construct custom SQL or use

date_list = Note.objects.all().dates('created', 'year')

for years in date_list:
    Note.objects.filter(created__year = years.year)

This is the way it is done in date based generic views.