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Python / Django iterates a single list, checking inside an Object

What will be the cleanest path to the next pseudo-code?

class Player
   id
   name

class Participant  (is a subset of Player with an added status)
   player_id (ForeignKey to Player)
   status

So, you can have a list of players (Wayne, Chuck, Bobby) And then a list of participants (Wayne (status: YES), Bobby (status: NO)) Please note that Chuck is not on the list of participants.

So, I repeat all the players and issue the status, if the participants exist.

player_list = list with Player objects
participant_list = list with Participant objects

for player in player_list:
   if player.id exists in participant_list //QUESTION IS HERE: HOW DO I DO THIS???
         print participant.status

I'm not sure how to check the internal id of a list that contains objects ???

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5 answers

add to another loop

player_list = list with Player objects
participant_list = list with Participant objects

for player in player_list:
    for participant in participant_list:
        if player == participant.player:
            print participant.status
            break

Not the most pleasant solution, but simple.

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You want values_list()for objects QuerySet.

player_list = Player.objects.filter(...)
participant_list = Participant.objects.filter(...)
participant_player_id_list = participant_list.values_list('player_id', flat=True)

for player in player_list:
    if player.id in participant_player_id_list:
        print participant_list.get(player_id=player.id).status
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/ :

player_list = Player.objects.all()

# Get all relevant participants (or just all if you like)
player_ids = player_list.value_list('id', flat=True)
participant_list = Participant.objects.filter(player_id__in=player_ids)

# Create a lookup dict
participants = dict([(p.player_id, p) for p in participant_list])

# Everything is now prepared for quick access
for player in player_list:
    if player.id in participants:
        print participants[player.id].status

, . .

. /:

class Player(models.Model):
    name = models.CharField(max_length=128)
    is_participant = models.BooleanField(default=False)

class Participant(Player):
    status = models.CharField(max_length=32)

    def save(self, *args, **kwargs):
        if not self.id:
            self.is_participant = True
        super(Participant, self).save(*args, **kwargs)

, , Participant , Player, , , . . , Player. None , , .

- , , Participant. , , :

class Player(models.Model):
    name = models.CharField(max_length=128)
    participant_status = models.CharField(max_length=32)

class Participant(Player):
    pass

:

for player in Player.objects.all()
    if player.participant_status:
         print participant.status

, . , a) b) .

, , , , , .

" "

OneToOneField, . , , select_related(), , .

class Player(models.Model):
    name = models.CharField(max_length=128)
    participant = models.OneToOneField('Participant', null=True)

class Participant(models.Model):
    status = models.CharField(max_length=32)

:

player_list = Player.objects.all().select_related('participant')

for player in player_list:
   if player.participant_id is not None:
     print player.participant.status
+2

, 2x, python/django, , , . values_list in_bulk , id . - python, set . :

import operator

# Get a bulk dict of player objects.
pl_objs = Player.objects
bulk_players = pl_objs.in_bulk(pl_obj.values_list("id", flat=True))

# Get a bulk dict mapping player.id to Participant instances.
bulk_participants = dict((operator.attrgetter("player_id"), x) 
                          for x in Participant.objects.all())

# Now find the overlap with a set intersection; print status.
for _id in set(bulk_players) & set(bulk_participants):
    print bulk_participants[_id].status
0

, :

player_list = list with Player objects
participant_list = list with Participant objects

for player, participant in zip(player_list, participant_list):
    if player == participant.player:
            print participant.status
            break

player_list participant_list

-1

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