为什么Django没有为我的模型创建一个外键？

Question

我的模型代码如下：

from django.db import models

# Create your models here.
class Post(models.Model):
    title = models.CharField(max_length = 30)
    text = models.CharField(max_length = 150)

class Comment(models.Model):
    text = models.CharField(max_length = 150)
    post = models.ForeignKey(Post)

正在运行

python manage.py sqlall yabe

结果：

Mac-mini:yabedjango hn$ python manage.py sqlall yabe
BEGIN;
CREATE TABLE "yabe_post" (
    "id" serial NOT NULL PRIMARY KEY,
    "title" varchar(30) NOT NULL,
    "text" varchar(150) NOT NULL
)
;
CREATE TABLE "yabe_comment" (
    "id" serial NOT NULL PRIMARY KEY,
    "text" varchar(150) NOT NULL
)
;

COMMIT;
Mac-mini:yabedjango hn$

我期望在yabe_comment中有一个外键。Python版本：

Python 2.7.4 (v2.7.4:026ee0057e2d, Apr  6 2013, 11:43:10)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.

Django版本：

django-admin.py --version
1.5.1

Answer 1

你错过了整个输出。我复制了你的模型并试过了。command：manage.py sqlall app_name的整个输出是：

BEGIN;
CREATE TABLE `head_post` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `title` varchar(30) NOT NULL,
    `text` varchar(150) NOT NULL
)
;
CREATE TABLE `head_comment` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `text` varchar(150) NOT NULL,
    `post_id` integer NOT NULL
)
;
ALTER TABLE `head_comment` ADD CONSTRAINT `post_id_refs_id_b2b5e564` FOREIGN KEY (`post_id`) REFERENCES `head_post` (`id`);
CREATE INDEX `head_comment_87a49a9a` ON `head_comment` (`post_id`);

COMMIT;

PS。head是我使用的应用程序名称。

Answer 2

python manage.py sql yabe

你可以看到"post_id" integer NOT NULL REFERENCES "blog_post" ("id")

BEGIN;
CREATE TABLE "blog_post" (
    "id" integer NOT NULL PRIMARY KEY,
    "title" varchar(30) NOT NULL,
    "text" varchar(150) NOT NULL
)
;
CREATE TABLE "blog_comment" (
    "id" integer NOT NULL PRIMARY KEY,
    "text" varchar(150) NOT NULL,
    "post_id" integer NOT NULL REFERENCES "blog_post" ("id")
)
;

我想这对你有帮助