python - Django mysql 表名未验证

Question

我将类添加到 Django 应用程序模型以创建 mysql 表。我在“歌曲”表中有“下载”表和“下载”列。

当我想同步数据库时，Django 返回错误:

CommandError: One or more models did not validate:
mp3mid.downloads: Reverse query name for field 'song' clashes with field 'songs.downloads'. Add a related_name argument to the definition for 'song'.

为什么表和列不能重名？

这是我的模型.py:

from django_evolution.mutations import *
from django.db import models

class singers(models.Model):
    name = models.CharField(max_length = 255)
    category = models.ForeignKey(categories)

class songs(models.Model):
    name = models.CharField(max_length = 255)
    singer = models.ForeignKey(singers)
    downloads = models.IntegerField(max_length = 11)
    exclusive = models.BooleanField(default = 0)
    hit = models.BooleanField(default = 0)
    date = models.DateTimeField(auto_now_add = True)
    link = models.CharField(max_length = 255)

class downloads(models.Model):
    song = models.ForeignKey(songs)
    date = models.DateTimeField(auto_now_add = True)

Answer 1

Django 允许您 make queries that span relationships .

在您的情况下，从 downloads 到 songs 的外键意味着您通常可以按照从歌曲到下载的关系向后查询:

from datetime import datetime
# fetch all songs with a download with a date on or after 2013-05-01.
songs = song.objects.filter(downloads__date__gte=datetime(2013,5,1))

但是，在这种情况下您不能这样做，因为 downloads 与您的 songs.downloads 字段冲突。

您有几个选择。首先，您可以设置 related_name为您的外键，如您的错误消息所建议的那样。

class downloads(models.Model):
    song = models.ForeignKey(songs, related_name="related_downloads")

或者，您可以重命名您的 song.downloads 字段。

class songs(models.Model):
    ...
    num_downloads = models.IntegerField(max_length = 11)

顺便说一句，我建议您将模型重命名为 Singer、Song 和 Download(大写，单数而不是复数)，以便遵循 Django 约定。