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用于配置文件的 OneToOneField

通过配对记录扩展模型

用于配置文件的 OneToOneField 是 CoddyKit 上的免费 Django Academy 课时。这是第 3 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Django Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Django Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Exactly One Each Way

Sometimes a row pairs with exactly one other row, both ways. That is a one-to-one relationship, perfect for splitting data cleanly.

The Profile Pattern

The classic use is a user profile: each user gets one profile, and each profile belongs to one user. Extra fields live separately.

Declaring OneToOneField

Add a OneToOneField pointing at the other model. It behaves like a ForeignKey with a built-in uniqueness guarantee.

class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)

Unique Under the Hood

A OneToOneField is really a ForeignKey marked unique. That constraint stops two profiles from ever sharing one user.

on_delete Still Applies

Like any link, it needs on_delete. With CASCADE, deleting the user removes their profile too in one step.

user = models.OneToOneField(User, on_delete=models.CASCADE)

Why Not Just Add Fields?

You could pile fields onto the original model, but a separate profile keeps it tidy and avoids touching tables you do not own.

Forward Access

From the profile, read the linked user straight through the field. It returns the single connected object.

profile = Profile.objects.first()
print(profile.user.username)

Reverse Access

The reverse side is special: from a user you reach the profile with a lowercase model name, no _set suffix needed.

user = User.objects.first()
print(user.profile.bio)

Creating a Profile

Make a profile by passing the user it pairs with. The unique constraint blocks a second profile for that same user.

Profile.objects.create(user=user, bio="Hello!")

Auto-Creating with Signals

A common trick is a post_save signal that builds a profile the moment a user is created, so the pair always exists.

Querying Across the Pair

Filter through the link with the double underscore, reaching the profile's fields from the user side or vice versa.

User.objects.filter(profile__bio__icontains="django")

Quick Check

Each user must have at most one profile, and each profile one user. Which field models this?

Recap

Great job! A OneToOneField pairs two rows uniquely, and the reverse is reached by the model's lowercase name. 👤

常见问题解答

「用于配置文件的 OneToOneField」课时是免费的吗？

是的 — 「用于配置文件的 OneToOneField」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Django Academy 课程的其余内容，请升级到 CoddyKit PRO。 Django Academy 课程共包含 4 节课。

「用于配置文件的 OneToOneField」这节课中我会学到什么？

通过配对记录扩展模型你通过在浏览器中直接运行的动手代码来练习 Django Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Django Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Django Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 3 节课，共 4 节。

「用于配置文件的 OneToOneField」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Django Academy 课中编写并运行代码吗？

能。每节 Django Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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