django models.py 使用外部字段排序

Question

我正在使用 django1.7，我有两个模型。

我的一个模型我想通过一个外国模型上的字段来指定ordering。这两个模型通过外键链接。

这是我的两个示例模型：

class ObjectiveDetails(models.Model, FillableModelWithLanguageVersion):
    user = models.ForeignKey(User)
    language_version = models.ForeignKey('LanguageVersion')
    field = models.TextField(null=False, blank=False, max_length=5000)
    objective_timestamp_added = models.DateTimeField(auto_now_add=True, auto_now=False)
    objective_timestamp_updated = models.DateTimeField(auto_now=True, auto_now_add=False)

    class Meta:
        ordering = ['language_version.language_code', 'id']

class LanguageVersion(models.Model):
    """Language version selection for a user"""
    user = models.ForeignKey(User)
    language_code = models.CharField(max_length=32)
    language_code_disabled = models.BooleanField(default=False)
    language_version_timestamp_added = models.DateTimeField(auto_now_add=True, auto_now=False)
    language_version_timestamp_updated = models.DateTimeField(auto_now=True, auto_now_add=False)  # the date the language version is updated when the user changes their subscription type.

我正在尝试通过 LanguageVersion 模型上的 language_code 订购 ObjectiveDetails。

我已经尝试了几次，但我都做不好。我已阅读文档并搜索了 SO 和 Google，但找不到正确答案，

Answer 1

将 language_code 排序添加到 LanguageVersion 并从 ObjectiveDetails 中删除 .language_code

您添加的每个外键都会 也隐式包含其所有默认排序。

https://docs.djangoproject.com/en/1.7/ref/models/options/#ordering

你的模型会是这样的

class ObjectiveDetails(models.Model, FillableModelWithLanguageVersion):
    user = models.ForeignKey(User)
    language_version = models.ForeignKey('LanguageVersion')
    field = models.TextField(null=False, blank=False, max_length=5000)
    objective_timestamp_added = models.DateTimeField(auto_now_add=True, auto_now=False)
    objective_timestamp_updated = models.DateTimeField(auto_now=True, auto_now_add=False)

    class Meta:
        ordering = ['language_version', 'id']

class LanguageVersion(models.Model):
    """Language version selection for a user"""
    user = models.ForeignKey(User)
    language_code = models.CharField(max_length=32)
    language_code_disabled = models.BooleanField(default=False)
    language_version_timestamp_added = models.DateTimeField(auto_now_add=True, auto_now=False)
    language_version_timestamp_updated = models.DateTimeField(auto_now=True, auto_now_add=False)  # the date the language version is updated when the user changes their subscription type.

    class Meta:
        ordering = ['language_code']