Question

我正在尝试使用DetailView在渲染到模板之前操纵上下文数据。更改主模型（Collection）上的属性可以正常工作，但更改第二个表（Song）上的属性不会改变任何内容。

Models.py

from django.db import models

class Collection(models.Model):
    collection_id = models.IntegerField(primary_key=True)
    name = models.CharField(max_length=250)
    artist_display_name = models.CharField(max_length=250)
    songs = models.ManyToManyField('Song', through='CollectionSong')

class CollectionSong(models.Model):
    collection = models.ForeignKey('Collection')
    song = models.ForeignKey('Song')
    track_number = models.IntegerField()
    volume_number = models.IntegerField()

class Song(models.Model):
    song_id = models.IntegerField(primary_key=True)
    name = models.CharField(max_length=250)
    artist_display_name = models.CharField(max_length=250)
    track_length = models.IntegerField()

Views.py

from django.views.generic import DetailView
from .models import Collection

class AlbumView(DetailView):
    model = Collection
    template_name = 'album.html'
    context_object_name = 'collection'

    def get_context_data(self, **kwargs):
        context = super(AlbumView, self).get_context_data(**kwargs)

        context['collection'].name = "YYY" # This works

        for song in context['collection'].songs.all():
            song.name = "XXX" # This does not work

        return context

Answer 1

这不起作用，因为每次查询集都会从数据库中返回新数据（它在引擎盖下缓存但我们可以认为是新鲜的）所以在将数据保存到数据库之前它不会返回更改的数据。

如何使用ManyToManyField操作视图中的上下文数据

1 个答案: