Question

I have 3 model classes:

class Team(models.Model):
    name = models.CharField(max_length=100, default="", blank=True, null=True)
    number = models.IntegerField() 

class Position(models.Model):
    match = models.ForeignKey('Match')
    color = models.CharField(max_length=5)
    number = models.IntegerField()

    team = models.ForeignKey('Team')

class Match(models.Model):
    type = models.CharField(max_length=3)
    number = models.IntegerField()

    red_score = models.IntegerField(default=0)
    blue_score = models.IntegerField(default=0)

    match_events = models.TextField(max_length=1000)

Using the models as they are right now, how would I able to get a list of Matches a Team has won (i.e. if the Team belongs to a red Position, add it to the list if its Match has a red_score > blue_score)

Sorry if that’s confusing. I can try to clarify if you have any specific questions.

Thanks!

Answer 1

Simplest way to do this:

Match.objects.filter(position__color='red', red_score__gt=F('blue_score'))

You may want to move Position model to the bottom, to remove apostrophes from foreign key related models names.

This is as well very good example to use ManyToMany relation:

class Team(models.Model):
    name = models.CharField(max_length=100, default="", blank=True, null=True)
    number = models.IntegerField()


class Match(models.Model):
    type = models.CharField(max_length=3)
    number = models.IntegerField()
    red_score = models.IntegerField(default=0)
    blue_score = models.IntegerField(default=0)
    match_events = models.TextField(max_length=1000)
    teams = models.ManyToManyField(Team, through='Position',
                                   related_name='matches')


class Position(models.Model):
    match = models.ForeignKey(Match)
    color = models.CharField(max_length=5)
    number = models.IntegerField()
    team = models.ForeignKey(Team)

In this case, you will get few more options to simplify data access, e.g.:
if team is your actual team and match single match selected somewhere earlier in the code, this is valid:

team.matches.filter(red_score__gt=F('blue_score')) # all won matches of this team

match.teams.all() # teams involved in this match