Как вывести данные «песня — исполнители» из связи М2М в админке?

Question

[dr sbtn]

как сделать, чтобы в админке в Song выводился список "исполнитель - название песни" ? return что?

class Song(models.Model):
    name_song = models.CharField(max_length=30)
    ...
    musician = models.ManyToManyField(Musician)

    def __str__(self):
        return self.name_song

Answer 1

[dr sbtn]

Roman Kitaev помог решить проблему:

def __str__(self):
	return '%s - %s' % (', '.join(map(str, self.musician.all())), self.name_song)

Comments

[Animkim]

Используйте format это вроде как современный вариант.

[sim3x]

return '{} - {}'.format(', '.join(map(str, self.musician.all())), self.name_song)

[Roman K]

Animkim: sim3x: Для таких простых строк проще и менее нагружено юзать Си-подобный синтаксис. К тому же, быстрее:

[Animkim]

Roman Kitaev: ничоси, правда думал что format шустрее.
А если строки сложные выигрывает format?

[Roman K]

Animkim: https://www.python.org/dev/peps/pep-3101/

[sim3x]

In [3]: %timeit '%s - %s' % ('str1', 'str2')
10000000 loops, best of 3: 21.5 ns per loop

In [4]: %timeit '{} - {}'.format('str1', 'str2')
1000000 loops, best of 3: 380 ns per loop

In [6]: s1= ''' is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.'''

In [7]: s2 = '''It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content here, content here', making it look like readable English. Many desktop publishing packages and web page editors now use Lorem Ipsum as their default model text, and a search for 'lorem ipsum' will uncover many web sites still in their infancy. Various versions have evolved over the years, sometimes by accident, sometimes on purpose (injected humour and the like).'''

In [8]: %timeit '{} - {}'.format(s1, s2)
1000000 loops, best of 3: 929 ns per loop

In [9]: %timeit '%s - %s' % (s1, s2)
1000000 loops, best of 3: 675 ns per loop

Answer 2

[Владислав]

def __str__(self):
    return '{} - {}'.format(self.name_song, self.musician)

Comments

[dr sbtn]

второе после self - musician, но я поняла, спасибо!

[dr sbtn]

Только вот теперь выводится в виде
justlyrics_app.Musician.None - Nothing but trouble,
Хотя исполнителя выбрала.

[Владислав]

воу, да я совсем слепой. не увидел, что связь многие-ко-многим.

[Владислав]

я не помню точно, как от musician получить список исполнителей.
вместо self.musician попробуй подставить ', '.join(self.musician.objects.all())

Answer 3

[Skver0]

admin.py

from django.contrib import admin
from models import *


class MusicianAdmin(admin.ModelAdmin):
    list_filter = ('musician', )
    filter_horizontal = ('musician', )

admin.site.register(Song, MusicianAdmin)