在Django模板中如何显示* linked *表中的字段值？ [英] How to display value of a field in a *linked* table, in a Django template?

问题描述

我正在创建一个演示Django网站，您可以浏览Billy Joel的专辑。您点击相册查看所有歌曲。

I am creating a demo Django website where you browse Billy Joel's albums . You click on an album to view all songs.

（如果恰好是： http://104.131.200.120/albums/all / - 目前几乎没有任何数据，冷泉港只有一首歌，无辜者中没有）

(If it happens to be on: http://104.131.200.120/albums/all/--there's hardly any data at the moment. Only one song in Cold Spring Harbor, none in An Innocent Man)

我可以'了解如何在相册页面中显示歌曲名称。它可以告诉你是否有一首歌，因为冷泉港打印出一个空的名字/描述行，而一个无辜的人没有。

I can't figure out how to display the song name in the album page. It can tell if there is a song, because Cold Spring Harbor prints out an empty "name/description" line, and An Innocent Man doesn't.

这是视图

def album(request, album_id=1):
    album = Album.objects.get(id=album_id)
    album_songs = AlbumSong.objects.filter(id=album_id)
    print(str(album_songs))
    return  render_to_response("album.html",
                               {"album": album, "album_songs" : album_songs})

（ print 结果 [ColdFlow Spring Harbor：10：Got To Begin Again>] 正在写入控制台，当Cold弹簧港被选中。）

(the print results in [<AlbumSong: Cold Spring Harbor: 10: Got To Begin Again>] being written to the console, when Cold Spring Harbor is selected.)

该模型（请注意，歌曲和专辑模型没有通过外键链接，有一个中间表AlbumSong）：

The model (note that the Song and Album models are not linked by foreign key. There's an intermediate table, AlbumSong):

from  django.db import models
from  django.contrib.auth.models import User
from  time import time

def get_upload_file_name(instance, filename):
    return  "uploaded_files/%s_%s" % (str(time()).replace(".", "_"), filename)

class Album(models.Model):
    title = models.CharField(max_length=70)
    pub_date = models.DateField('release date')
    is_official = models.BooleanField(default=False)
    is_concert = models.BooleanField(default=False)
    likes = models.IntegerField(default=0)
    thumbnail = models.FileField(upload_to=get_upload_file_name, blank=True, null=True)

    def __str__(self):
        return  self.title

class Song(models.Model):
    name = models.CharField(max_length=100)
    sub_name = models.CharField(max_length=200, null=True, blank=True)
    length_seconds = models.IntegerField()
    lyrics_url = models.TextField(default="", blank=True, null=True)

    def __str__(self):
        return  self.name

class AlbumSong(models.Model):
    song_id = models.ForeignKey(Song)
    album_id = models.ForeignKey(Album)
    sequence_num = models.IntegerField()

    class Meta:
        unique_together = ('album_id', 'sequence_num',)
        unique_together = ('album_id', 'song_id',)

    def __str__(self):
        return  str(self.album_id) + ": " + str(self.sequence_num) + ": " + str(self.song_id)

class FavoriteSongs(models.Model):
    user_id = models.ForeignKey(User)
    song_id = models.ForeignKey(Song)
    sequence_num = models.IntegerField()

    class Meta:
        unique_together = ('user_id', 'song_id',)
        unique_together = ('user_id', 'sequence_num',)

    def __str__(self):
        return  "user=" + str(self.user_id) + ", song=" + str(self.song_id) + ", number=" + str(self.sequence_num)

class FavoriteAlbums(models.Model):
    user_id = models.ForeignKey(User)
    album_id = models.ForeignKey(Album)
    sequence_num = models.IntegerField()

    class Meta:
        unique_together = ('user_id', 'album_id',)
        unique_together = ('user_id', 'sequence_num',)

    def __str__(self):
        return  "user=" + str(self.user_id) + ", album=" + str(self.album_id) + ", number=" + str(self.sequence_num)

和模板：

{% extends "base.html" %}

{% block title %}Album detail{% endblock %}

<!-- <div id="sidebar"> -->
{% block sidebar %}
  <UL>
     <LI><a href="/albums/all">Albums</A></LI>
  </UL>
{% endblock %}
<!-- </div> -->


{% block content %}

<H1>{{ album.title }}</H1>

<P>{{ album.body }}</P>

{% if album.thumbnail %}
  <P><img src="/static/{{ album.thumbnail }}" width="200"/></P>
{% endif %}

<P><UL>
  <LI>Released: {{ album.pub_date }}</LI>
  <LI>Official: {{ album.is_official }}</LI>
  <LI>Concert: &nbsp;{{ album.is_concert }}</LI>
</UL></P>
  <H2>Songs</H2>

{% for  album_song in album_songs %}  <!-- No colon after "album_songs" -->
  <div>
  <P><UL>
     <LI>Name: <a href="/songs/get/{{ song.id }}">{{ album_song.song.name }}</a><UL>
        <LI>Description: {{ album_song.song.sub_name }}</LI>
     </UL></LI>
  </UL></P>
  </div>
{% endfor %}
<P><a href="/albums/like/{{ album.id }}">Like this album</A> -- {{ album.likes }} people liked this album.</P>

{% endblock %}

如何在模板？ album_song.song.name 应该更改为？

How do I display the song name in the template? What should album_song.song.name be changed to?

谢谢。

推荐答案

问题是您的字段名称。由于某些原因，您已经从AlbumSongsong_id和album_id中调用了外键。所以你应该在模板中使用相同的名字： {{album_song.song_id.name}} 。

The problem is your field names. For some reason, you've called your foreign keys from AlbumSong "song_id" and "album_id". So you should use the same names in the template: {{ album_song.song_id.name }}.

使用这个名字是没有意义的。 Django字段不代表一个ID，它代表了实际的Song对象。 Django已经创建了一个带有_id后缀的底层数据库字段，所以在这种情况下，它创建了一个名为song_id_id，这是愚蠢的。重命名您的字段歌曲和相册，并保持模板的方式。

However, it doesn't make sense to use this name. The Django field does not represent an ID, it represents the actual Song object. Django already creates an underlying database field with an "_id" suffix, so in this case it's created one called "song_id_id", which is silly. Rename your fields "song" and "album", and keep your template the way it is.

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