{"id":6182,"date":"2022-04-06T13:11:37","date_gmt":"2022-04-06T05:11:37","guid":{"rendered":"https:\/\/egonlin.com\/?p=6182"},"modified":"2022-04-16T19:45:22","modified_gmt":"2022-04-16T11:45:22","slug":"%e7%ac%ac%e4%b8%83%e8%8a%82%ef%bc%9a%e5%bb%ba%e7%ab%8b%e8%a1%a8%e5%85%b3%e7%b3%bb","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=6182","title":{"rendered":"\u7b2c\u4e03\u8282\uff1a\u5efa\u7acb\u8868\u5173\u7cfb"},"content":{"rendered":"

\u5efa\u7acb\u8868\u5173\u7cfb<\/h1>\n

\u663e\u7136\uff0c\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7684\u5f3a\u5927\u4e4b\u5904\u5c31\u5728\u4e8e\u5c06\u8868\u76f8\u4e92\u5173\u8054\uff0cDjango\u63d0\u4f9b\u4e86\u5b9a\u4e49\u4e09\u79cd\u6700\u5e38\u89c1\u7684\u6570\u636e\u5e93\u5173\u7cfb\u7c7b\u578b\u7684\u65b9\u6cd5\uff1a\u591a\u5bf9\u4e00\u3001\u591a\u5bf9\u591a\u548c\u4e00\u5bf9\u4e00\u3002<\/p>\n

\"\"<\/div><\/p>\n

\u4e00\u3001\u8868\u5173\u7cfb\u4e4b\u591a\u5bf9\u4e00<\/h2>\n

1\u3001\u591a\u5bf9\u4e00\u5173\u7cfb<\/p>\n

\u8981\u5b9a\u4e49\u4e00\u4e2a\u591a\u5bf9\u4e00\u5173\u7cfb\uff0c\u9700\u8981\u4f7f\u7528django.db.models.ForeignKey\u3002\u60a8\u53ef\u4ee5\u50cf\u4f7f\u7528\u4efb\u4f55\u5176\u4ed6\u5b57\u6bb5\u7c7b\u578b\u4e00\u6837\u53bb\u4f7f\u7528\u5b83\uff1a\u5c06\u5176\u4f5c\u4e3a\u6a21\u578b\u7684\u7c7b\u5c5e\u6027<\/p>\n

# ForeignKey\u7684\u53c2\u6570\uff1a\n1\u3001to\uff1a\u6240\u5173\u8054\u7684\u6a21\u578b\u7c7b\n\n2\u3001to_field: \u8bbe\u7f6e\u8981\u5173\u8054\u8868\u7684\u5b57\u6bb5\n3\u3001related_name: \u6b64\u5904\u6682\u4e14\u5ffd\u7565\uff0c\u4f1a\u5728\u540e\u7eed\u7ae0\u8282\u4e13\u95e8\u4ecb\u7ecd\n4\u3001related_query_name: \u6b64\u5904\u6682\u4e14\u5ffd\u7565\uff0c\u4f1a\u5728\u540e\u7eed\u7ae0\u8282\u4e13\u95e8\u4ecb\u7ecd\n5\u3001db_constraint\uff1a\u662f\u5426\u5728\u6570\u636e\u5e93\u4e2d\u521b\u5efa\u5916\u952e\u7ea6\u675f\uff0c\u9ed8\u8ba4\u4e3aTrue\u3002\n\n6\u3001on_delete\uff1a\u5f53\u5220\u9664\u5173\u8054\u8868\u4e2d\u7684\u6570\u636e\u65f6\uff0c\u5f53\u524d\u8868\u4e0e\u5176\u5173\u8054\u7684\u884c\u7684\u884c\u4e3a\uff0c\u503c\u53ef\u4ee5\u662f\u5982\u4e0b\n\u3000\u3000models.CASCADE\n\u3000\u3000\u5220\u9664\u5173\u8054\u6570\u636e\uff0c\u4e0e\u4e4b\u5173\u8054\u4e5f\u5220\u9664\n\n\u3000\u3000models.DO_NOTHING\n\u3000\u3000\u5220\u9664\u5173\u8054\u6570\u636e\uff0c\u5f15\u53d1\u9519\u8befIntegrityError\n\n\u3000\u3000models.PROTECT\n\u3000\u3000\u5220\u9664\u5173\u8054\u6570\u636e\uff0c\u5f15\u53d1\u9519\u8befProtectedError\n\n\u3000\u3000models.SET_NULL\n\u3000\u3000\u5220\u9664\u5173\u8054\u6570\u636e\uff0c\u4e0e\u4e4b\u5173\u8054\u7684\u503c\u8bbe\u7f6e\u4e3anull\uff08\u524d\u63d0FK\u5b57\u6bb5\u9700\u8981\u8bbe\u7f6e\u4e3a\u53ef\u7a7a\uff09\n\n\u3000\u3000models.SET_DEFAULT\n\u3000\u3000\u5220\u9664\u5173\u8054\u6570\u636e\uff0c\u4e0e\u4e4b\u5173\u8054\u7684\u503c\u8bbe\u7f6e\u4e3a\u9ed8\u8ba4\u503c\uff08\u524d\u63d0FK\u5b57\u6bb5\u9700\u8981\u8bbe\u7f6e\u9ed8\u8ba4\u503c\uff09\n\n\u3000\u3000models.SET(\u503c)\n\u3000\u3000\u5220\u9664\u5173\u8054\u6570\u636e\uff0c\u4e0e\u4e4b\u5173\u8054\u7684\u503c\u8bbe\u7f6e\u4e3a\u6307\u5b9a\u503c\n\n   models.SET(\u53ef\u6267\u884c\u5bf9\u8c61)\n\u3000\u3000\u5220\u9664\u5173\u8054\u6570\u636e\uff0c\u4e0e\u4e4b\u5173\u8054\u7684\u503c\u8bbe\u7f6e\u4e3a\u53ef\u6267\u884c\u5bf9\u8c61\u7684\u8fd4\u56de\u503c\uff0c\u4f8b\u5982\n   def func():\n       return 10\n\n   class MyModel(models.Model):\n       user = models.ForeignKey(\n            to="User",\n            to_field="id"\uff0c\n            on_delete=models.SET(func)\n       )<\/code><\/pre>\n
\u4f8b\u5982\uff1a<\/p>\n
from django.db import models\n\nclass Manufacturer(models.Model):  # \u6c7d\u8f66\u5236\u9020\u5546\n    # ...\n    pass\n\nclass Car(models.Model):  # \u6c7d\u8f66\n    manufacturer = models.ForeignKey(to=Manufacturer, on_delete=models.CASCADE)\n    # ...<\/code><\/pre>\n
\u5efa\u8bae\uff08\u4f46\u4e0d\u662f\u5fc5\u9700\u7684\uff09ForeignKey\u5b57\u6bb5\u7684\u540d\u79f0\u662f\u6a21\u578b\u7684\u540d\u79f0\u3001\u5c0f\u5199\uff08\u5982\u4e0a\u8ff0manufacturer\uff09\uff0c\u8fd9\u4e48\u505a\u662f\u4e3a\u4e86\u5728\u540e\u671f\u8fdb\u884c\u67e5\u8be2\u64cd\u4f5c\u65f6\u65b9\u4fbf\u81ea\u5df1\u8bc6\u522b\u3002\u5f53\u7136\uff0c\u4f60\u60f3\u53eb\u4ec0\u4e48\u5c31\u53eb\u4ec0\u4e48\u3002\u4f8b\u5982\uff1a<\/p>\n
class Car(models.Model):\n    company_that_makes_it = models.ForeignKey(\n        Manufacturer,\n        on_delete=models.CASCADE,\n    )\n    # ...<\/code><\/pre>\n
*2\u3001\u60f0\u6027\u5173\u7cfb*<\/em><\/strong><\/p>\n
\u4e0a\u8ff0\u5173\u8054\u5173\u7cfb\u7684\u5efa\u7acb\uff0c\u7531\u4e8eForeignKey\u7684\u7b2c\u4e00\u4e2a\u4f4d\u7f6e\u53c2\u6570\u662f\u6a21\u578b\u7c7b\uff0c\u6240\u4ee5\u6a21\u578bCar\u5fc5\u987b\u5728Manufacturer\u4e4b\u540e\uff0c\u82e5\u60f3\u6392\u9664\u5148\u540e\u987a\u5e8f\u5e26\u6765\u7684\u56f0\u6270\uff0c\u5373\u9700\u8981\u521b\u5efa\u4e0e\u5c1a\u672a\u5b9a\u4e49\u7684\u6a21\u578b\u7c7b\u7684\u5173\u7cfb\uff0c\u53ef\u4ee5\u5c06ForeignKey\u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\u6362\u6210\u5b57\u7b26\u4e32\u5f62\u5f0f\uff0c\u5982\u4e0b\u6240\u793a\uff0c\u8fd9\u79cd\u5b9a\u4e49\u5173\u7cfb\u7684\u5f62\u5f0f\uff0c\u79f0\u4e4b\u4e3a\u60f0\u6027\u5173\u7cfb<\/p>\n
from django.db import models\n\nclass Car(models.Model):\n    manufacturer = models.ForeignKey('Manufacturer', on_delete=models.CASCADE)\n    # ...\n\nclass Manufacturer(models.Model):\n    # ...\n    pass<\/code><\/pre>\n
*3\u3001\u81ea\u5173\u8054*<\/em><\/strong><\/p>\n
class Comment(models.Model):\n    # \u8bc4\u8bba\u8005\n    user=models.ForeignKey(to='User',to_field='nid',on_delete=models.CASCADE)\n    # \u8bc4\u8bba\u7684\u6587\u7ae0\n    article=models.ForeignKey(to='Article',to_field='nid',on_delete=models.CASCADE)\n    # \u8bc4\u8bba\u7684\u5185\u5bb9\n    content=models.CharField(max_length=255)\n    # \u8bc4\u8bba\u65f6\u95f4\n    create_time=models.DateTimeField(auto_now_add=True)\n    # \u81ea\u5173\u8054\n    parent_comment=models.ForeignKey(to='self',on_delete=models.CASCADE,null=True)<\/code><\/pre>\n
*4\u3001\u5176\u4ed6*<\/em><\/strong><\/p>\n
# 1\u3001\u6570\u636e\u5e93\u8868\u793a\uff1a\n\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u5728\u6570\u636e\u5e93\u5c42\u9762\uff0cdjango\u4f1a\u5728ForeignKey\u7684\u5b57\u6bb5\u540e\u52a0\u540e\u7f00\u201c_id\u201d\uff0c\u5373\u4e0a\u8ff0\u6a21\u578b\u5b57\u6bb5manufacturer\u5bf9\u5e94\u7684\u6570\u636e\u5e93\u8868\u5b57\u6bb5\u4e3amanufacturer_id\uff08\u6211\u4eec\u53ef\u4ee5\u7528\u8fc7db_column\u9009\u9879\u6765\u8fdb\u884c\u81ea\u5b9a\u4e49\uff09\n\n\u4f46\u662f\uff0c\u6211\u4eec\u5728\u64cd\u4f5c\u6a21\u578b\u65f6\u53ea\u9700\u8981\u57fa\u4e8e\u6a21\u578b\u5b57\u6bb5\u540d\u5b57\u5373\u53ef\uff0c\u53ea\u6709\u5728\u7f16\u5199\u539f\u751fsql\u65f6\u624d\u9700\u8981\u8003\u8651\u6570\u636e\u5e93\u91cc\u7684\u5b57\u6bb5\u3002\n\n# 2\u3001db_index\ndjango\u4f1a\u81ea\u52a8\u4e3aForeignKey\u5b57\u6bb5\u521b\u5efa\u7d22\u5f15\uff0c\u53ef\u4ee5\u6307\u5b9adb_index=False\u6765\u7981\u7528\u6b64\u529f\u80fd\u3002\n\n\u5982\u679c\u6211\u4eec\u521b\u5efa\u5916\u952e\u7684\u76ee\u7684\u662f\u4e3a\u4e86\u4e00\u81f4\u6027\u800c\u4e0d\u662f\u94fe\u63a5\uff0c\u6216\u8005\u4f60\u9700\u8981\u4f7f\u7528\u81ea\u5b9a\u4e49\u7684\u90e8\u5206\u6216\u591a\u5217\u7d22\u5f15\uff0c\u90a3\u4e48\u9700\u8981\u5c06db_index\u8bbe\u7f6e\u4e3aFalse\n\n# 3\u3001ForeignKey\u7684\u5176\u4ed6\u8be6\u7ec6\u53c2\u6570\nhttps:\/\/docs.djangoproject.com\/en\/3.0\/ref\/models\/fields\/#arguments<\/code><\/pre>\n
\u4e8c\u3001\u8868\u5173\u7cfb\u4e4b\u591a\u5bf9\u591a<\/h2>\n
*1\u3001\u591a\u5bf9\u591a\u5173\u7cfb*<\/em><\/strong><\/p>\n
\u5b9a\u4e49\u591a\u5bf9\u591a\u5173\u7cfb\uff0c\u9700\u8981\u4f7f\u7528ManyToManyField\uff0c\u60a8\u540c\u6837\u53ef\u4ee5\u50cf\u4f7f\u7528\u4efb\u4f55\u5176\u4ed6\u5b57\u6bb5\u7c7b\u578b\u4e00\u6837\u53bb\u4f7f\u7528\u5b83\uff1a\u5c06\u5176\u4f5c\u4e3a\u6a21\u578b\u7684\u7c7b\u5c5e\u6027<\/p>\n
# ManyToManyField\u53c2\u6570\uff1a\n1\u3001to\uff1a\u6240\u5173\u8054\u7684\u6a21\u578b\u7c7b\n\n2\u3001to_field: \u8bbe\u7f6e\u8981\u5173\u8054\u8868\u7684\u5b57\u6bb5\n3\u3001related_name: \u540cForeignKey\uff0c\u6b64\u5904\u6682\u4e14\u5ffd\u7565\uff0c\u4f1a\u5728\u540e\u7eed\u7ae0\u8282\u4e13\u95e8\u4ecb\u7ecd\n4\u3001related_query_name: \u540cForeignKey\uff0c\u6b64\u5904\u6682\u4e14\u5ffd\u7565\uff0c\u4f1a\u5728\u540e\u7eed\u7ae0\u8282\u4e13\u95e8\u4ecb\u7ecd\n5\u3001db_constraint\uff1a\u662f\u5426\u5728\u6570\u636e\u5e93\u4e2d\u521b\u5efa\u5916\u952e\u7ea6\u675f\uff0c\u9ed8\u8ba4\u4e3aTrue\u3002\n6\u3001db_table: \u9ed8\u8ba4\u521b\u5efa\u7b2c\u4e09\u5f20\u8868\u65f6\uff0c\u6570\u636e\u5e93\u4e2d\u8be5\u8868\u7684\u540d\u79f0\u3002\n\n7\u3001symmetrical\uff1a\u9ed8\u8ba4\u4e3aTrue\uff0c\u6b64\u5904\u6682\u4e14\u5ffd\u7565\uff0c\u4f1a\u5728\u540e\u7eed\u7ae0\u8282\u4e13\u95e8\u4ecb\u7ecd\n8\u3001through: \u8be6\u89c1\u672c\u8282"3\u3001\u591a\u5bf9\u591a\u989d\u5916\u7684\u5b57\u6bb5\uff1a\u4e2d\u95f4\u6a21\u578b"\n9\u3001through_fileds\uff1a\u8be6\u89c1\u672c\u8282"3\u3001\u591a\u5bf9\u591a\u989d\u5916\u7684\u5b57\u6bb5\uff1a\u4e2d\u95f4\u6a21\u578b"\n\n# MannyToMany\u7684\u5176\u4ed6\u8be6\u7ec6\u53c2\u6570\uff1ahttps:\/\/docs.djangoproject.com\/en\/3.0\/ref\/models\/fields\/#manytomany-arguments<\/code><\/pre>\n
\u4f8b\u5982<\/p>\n
from django.db import models\n\nclass Topping(models.Model): # \u9985\u6599\n    # ...\n    pass\n\nclass Pizza(models.Model): # \u62ab\u8428\n    # ...\n    toppings = models.ManyToManyField(Topping)\n\n# \u6570\u636e\u5e93\u8868\u793a\uff1a\n\u5728\u5e55\u540e\uff0cDjango\u521b\u5efa\u4e00\u4e2a\u4e2d\u95f4\u8fde\u63a5\u8868\u6765\u8868\u793a\u591a\u5bf9\u591a\u5173\u7cfb\u3002\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u6b64\u8868\u540d\u662f\uff1a\u5305\u542b\u8be5\u5b57\u6bb5\u7684\u6a21\u578b\u7684\u8868\u540d_\u591a\u5bf9\u591a\u5b57\u6bb5\u7684\u540d\u79f0\u3002\u53ef\u4ee5\u4f7f\u7528db_table\u9009\u9879\u624b\u52a8\u8bbe\u7f6e\u8fde\u63a5\u8868\u7684\u540d\u79f0\u3002<\/code><\/pre>\n
\u5efa\u8bae\uff08\u4f46\u4e0d\u662f\u5fc5\u987b\uff09ManyToMany\u7684\u5b57\u6bb5\u540d\u79f0\uff08\u4e0a\u4f8b\u4e2d\u7684toppings\uff09\u662f\u4e00\u4e2a\u5173\u8054\u7684\u6a21\u578b\u7c7b\u540d\u5b57\u7684\u590d\u6570\u5f62\u5f0f\uff0c\u7528\u4e8e\u63cf\u8ff0\u76f8\u5173\u6a21\u578b\u5bf9\u8c61\u96c6\u3002<\/p>\n
\u9488\u5bf9ManyToMany\u5b57\u6bb5\uff0c\u53ea\u8981\u4e0d\u662f\u540c\u65f6\u653e\u5165\u4e24\u4e2a\u6a21\u578b\u4e2d\uff0c\u5728\u54ea\u4e2a\u6a21\u578b\u4e2d\u521b\u5efa\u5e76\u4e0d\u91cd\u8981\uff0c\u4f46\u662f\u901a\u5e38\u60c5\u51b5\u4e0b\u6211\u4eec\u9700\u8981\u8003\u8651\u903b\u8f91\u4e0a\u7684\u901a\u987a\u5df2\u7ecf\u540e\u671f\u7684\u4f7f\u7528\u65b9\u4fbf\uff0c\u5b57\u6bb5\u4e0e\u7c7b\u662f\u4e00\u4e2a\u4ece\u5c5e\u5173\u7cfb\uff0ctoppings\u5b57\u6bb5\u5728\u7c7bPizza\u91cc\uff0c\u6211\u4eec\u53ef\u4ee5\u8bf4Pizza\u62e5\u6709toppings\uff0c\u7ffb\u8bd1\u4e00\u4e0b\u5c31\u662f\u62ab\u8428\u6709\u9985\u6599\uff0c\u663e\u800c\u6613\u89c1\u8fd9\u6bd4\u5728Topping\u7c7b\u91cc\u653e\u5165MannyToMany\u5b57\u6bb5\uff0c\u903b\u8f91\u4e0a\u66f4\u901a\u987a\uff0c\u4ece\u800c\u4f7f\u5f97\u540e\u671f\u7684\u4f7f\u7528\u66f4\u4e3a\u65b9\u4fbf<\/p>\n
*2\u3001\u60f0\u6027\u5173\u7cfb*<\/em><\/strong><\/p>\n
\u540cForeignKey\u4e00\u6837<\/p>\n
*3\u3001\u591a\u5bf9\u591a\u989d\u5916\u7684\u5b57\u6bb5\uff1a\u4e2d\u95f4\u6a21\u578b*<\/em><\/strong><\/p>\n
\u4f7f\u7528\u6807\u51c6\u7684ManyToManyField\u521b\u5efa\u591a\u5bf9\u591a\u5173\u7cfb\u65f6\uff0c\u4f1a\u81ea\u52a8\u751f\u6210\u7b2c\u4e09\u5f20\u5173\u7cfb\u8868\uff0c\u800c\u5173\u7cfb\u8868\u4e2d\u53ea\u5b58\u653e\u4e86\u6700\u57fa\u672c\u7684\u6570\u636e\uff0c\u5373\u4e24\u4e2a\u6a21\u578b\u7684\u5173\u8054\u5173\u7cfb\uff0c\u5927\u591a\u6570\u60c5\u51b5\u4e0b\u8fd9\u662f\u6ca1\u95ee\u9898\u7684\uff0c\u5982\u4e0b<\/p>\n
from django.db import models\n\nclass Book(models.Model):\n    title = models.CharField(max_length=32)\n\nclass Author(models.Model):\n    name = models.CharField(max_length=32)\n    books = models.ManyToManyField(to="Book")\n\n# \u4f1a\u81ea\u52a8\u751f\u6210\u7b2c\u4e09\u5f20\u8868\uff0c\u7528\u6765\u5b58\u653e\u57fa\u672c\u7684\u5173\u8054\u5173\u7cfb\uff0c\u8f6c\u6362\u6210\u7c7b\u4f3c\u4e0b\u9762\u7684sql\ncreate table book(id int primary key);\ncreate table author(id int primary key);\n\ncreate table app01_author_books(\n    id int primary key auto_increment,\n    author_id int,\n    book_id int,\n    foreign key(author_id) references Author(id) on delete cascade,\n    foreign key(book_id) references Book(id) on delete cascade,\n    unique(author_id,book_id)\n);<\/code><\/pre>\n
\u4f46\u5982\u679c\u6211\u4eec\u9700\u8981\u5728\u4e24\u4e2a\u6a21\u578b\u7684\u591a\u5bf9\u591a\u5173\u7cfb\u4e0a\u6dfb\u52a0\u989d\u5916\u7684\u6570\u636e\uff08\u6bd4\u5982\u6709\u8fd9\u6837\u4e00\u4e2a\u5e94\u7528\uff0c\u5b83\u8bb0\u5f55\u97f3\u4e50\u5bb6Person\u6240\u5c5e\u7684\u97f3\u4e50\u5c0f\u7ec4Group\u3002\u6211\u4eec\u60f3\u5728\u591a\u5bf9\u591a\u5173\u7cfb\u7684\u57fa\u7840\u4e0a\uff0c\u77e5\u9053\u66f4\u591a\u6210\u5458\u5173\u7cfb\u7684\u7ec6\u8282\uff0c\u6bd4\u5982\u6210\u5458\u662f\u4f55\u65f6\u52a0\u5165\u5c0f\u7ec4\u7684,\u52a0\u5165\u7684\u7406\u7531\u662f\u4ec0\u4e48\uff09\uff0c
\n\u5c31\u9700\u8981\u6211\u4eec\u81ea\u5b9a\u4e49\u7b2c\u4e09\u5f20\u5173\u7cfb\u8868\u4e86\uff0c\u4f60\u53ef\u80fd\u4f1a\u60f3\u5230\u8fd9\u4e48\u505a<\/p>\n
from django.db import models\n\nclass Person(models.Model):\n    name = models.CharField(max_length=128)\n\nclass Group(models.Model):\n    name = models.CharField(max_length=128)\n\nclass Membership(models.Model):\n    person = models.ForeignKey(Person, on_delete=models.CASCADE)\n    group = models.ForeignKey(Group, on_delete=models.CASCADE)\n    date_joined = models.DateTimeField(auto_now_add=True)\n    invite_reason = models.CharField(max_length=64)\n\n    class Meta:\n        # \u6307\u5b9a\u672c\u6a21\u578b\u4e2d\u7684\u4e24\u4e2a\u5b57\u6bb5person\u4e0egroup\u8054\u5408\u552f\u4e00\n        unique_together = ("person", "group")<\/code><\/pre>\n
\u6b64\u65f6\u7b2c\u4e09\u5f20\u8868\u4fbf\u662f\u4e00\u5f20\u5b8c\u5168\u72ec\u7acb\u7684\u8868\uff0c\u8fd9\u672c\u8eab\u662f\u6ca1\u6709\u95ee\u9898\u7684\uff0c\u4f46Person\u4e0eGroup\u4e0e\u5176\u5173\u7cfb\u8868Membership
\n\u5b8c\u5168\u72ec\u7acb\u5f00\u610f\u5473\u7740\u6211\u4eec\u5c06\u65e0\u6cd5\u4f7f\u7528django\u63d0\u4f9b\u7684\u5173\u8054\u67e5\u8be2\u529f\u80fd\uff0c\u4e3a\u6b64\uff0cdjango\u63d0\u4f9b\u4e86\u4e00\u79cd\u6539\u8fdb\u65b9\u6848:"\u4f7f\u7528through\u53c2\u6570\u6307\u5b9a\u4e2d\u95f4\u6a21\u578b"\uff0c\u5982\u4e0b<\/p>\n
class Person(models.Model):\n    name = models.CharField(max_length=128)\n\nclass Group(models.Model):\n    name = models.CharField(max_length=128)\n    members = models.ManyToManyField(Person, through='Membership',through_fields=('group','person'))\n\n    """\n    through='Membership',\u6307\u5b9a\u4e2d\u95f4\u6a21\u578b\u4e3aMembership\n    \u5982\u679c\u4e2d\u4ecb\u6a21\u578bMembership\u4e2d\u6709\u591a\u4e2a\u5916\u952e\u90fd\u6307\u5411\u540c\u4e00\u4e2a\u6a21\u578b\uff0c\u90a3\u4e48\u5fc5\u987b\u6307\u5b9athrough_fields\u53c2\u6570\u8bf4\u660e\u5173\u8054\u7684\u4e24\u4e2a\u5b57\u6bb5\u662f\u8c01\uff0c\u6bd4\u5982through_fields=('person','group'),\n    \u5143\u7ec4\u5185\u7b2c\u4e00\u4e2a\u5b57\u6bb5\u4ee3\u8868\u5b9a\u4e49ManyToManyFiled\u7684\u90a3\u4e2a\u6a21\u578b\uff08\u6b64\u5904\u4e3aGroup\uff09\u5bf9\u5e94\u7684\u5916\u952e\u540d\u79f0\uff08\u6b64\u5904\u4e3a'group'\uff09\uff0c\u800c\u5143\u7ec4\u7684\u7b2c\u4e8c\u4e2a\u5b57\u6bb5\u4ee3\u8868\u76ee\u6807\u6a21\u578b\uff08\u6b64\u5904\u4e3aPerson\uff09\u5bf9\u5e94\u7684\u5916\u952e\u540d\u79f0\uff08\u6b64\u5904\u4e3a'person'\uff09\uff0c\u5207\u8bb0\u987a\u5e8f\u4e0d\u53ef\u4e71\n    """\n\nclass Membership(models.Model): # \u79f0\u4e4b\u4e3a\uff1a\u4e2d\u95f4\u6a21\u578b\/\u4e2d\u4ecb\u6a21\u578b\n    person = models.ForeignKey(Person, on_delete=models.CASCADE)\n    group = models.ForeignKey(Group, on_delete=models.CASCADE)\n    date_joined = models.DateTimeField(auto_now_add=True)\n    invite_reason = models.CharField(max_length=64)\n\n# ===========================\n\u8fd9\u6837Group\u4fbf\u53ef\u4ee5\u901a\u8fc7\u5b57\u6bb5members\u8fdb\u884c\u6b63\u5411\u67e5\u8be2\uff0cPerson\u4fbf\u53ef\u4ee5\u901a\u8fc7\u6a21\u578b\u540dgroup\u8fdb\u884c\u53cd\u5411\n\u67e5\u8be2\u4e86\n\n>>> p1=Person(name='\u725b\u903c\u9f13\u624b\u5c0fegon')\n>>> p2=Person(name='\u9a9a\u6d6a\u5409\u4ed6\u624b\u5218\u4e8c\u86cb')\n>>> p1.save()\n>>> p2.save()\n\n>>> g1=Group(name="\u72c2\u62fd\u70ab\u9177\u5c4c\u70b8\u5929\u4e50\u961f")\n>>> g2=Group(name="\u75af\u72c2\u7684\u5522\u5450\u4e50\u961f")\n>>> g1.save()\n>>> g2.save()\n\n#\u5f53\u6211\u4eec\u4f7f\u7528\u7b2c\u4e0a\u8ff0\u65b9\u5f0f\u521b\u5efa\u591a\u5bf9\u591a\u5173\u8054\u5173\u7cfb\u65f6\uff0c\u5c31\u65e0\u6cd5\u4f7f\u7528set\u3001add\u3001remove\u3001clear\u65b9\u6cd5\u6765\u7ba1\u7406\u591a\u5bf9\u591a\u7684\u5173\u7cfb\u4e86\uff0c\u9700\u8981\u901a\u8fc7\u7b2c\u4e09\u5f20\u8868\u7684model\u6765\u7ba1\u7406\u591a\u5bf9\u591a\u5173\u7cfb\u3002\n>>> Membership.objects.create(person=p1,group=g1,invite_reason='\u9700\u8981\u4e00\u540d\u725b\u903c\u7684\u9f13\u624b')\n<Membership: Membership object (1)>\n>>> Membership.objects.create(person=p2,group=g1,invite_reason='\u9700\u8981\u4e00\u540d\u9a9a\u6d6a\u5409\u4ed6\u624b')\n<Membership: Membership object (2)>\n>>> Membership.objects.create(person=p2,group=g2,invite_reason='\u9700\u8981\u4e00\u540d\u9a9a\u6d6a\u5409\u4ed6\u624b')\n<Membership: Membership object (2)>\n\n>>> g1.members.all()\n<QuerySet [<Person: \u725b\u903c\u9f13\u624b\u5c0fegon>, <Person: \u9a9a\u6d6a\u5409\u4ed6\u624b\u5218\u4e8c\u86cb>]>\n>>> g2.members.all()\n<QuerySet [<Person: \u9a9a\u6d6a\u5409\u4ed6\u624b\u5218\u4e8c\u86cb>]>\n>>> \n>>> p1.group_set.all()\n<QuerySet [<Group: \u72c2\u62fd\u70ab\u9177\u5c4c\u70b8\u5929\u4e50\u961f>]>\n>>> p2.group_set.all()\n<QuerySet [<Group: \u72c2\u62fd\u70ab\u9177\u5c4c\u70b8\u5929\u4e50\u961f>, <Group: \u75af\u72c2\u7684\u5522\u5450\u4e50\u961f>]>\n\n#clear()\u65b9\u6cd5\u5374\u662f\u53ef\u7528\u7684\u3002\u5b83\u53ef\u4ee5\u6e05\u7a7a\u67d0\u4e2a\u5b9e\u4f8b\u6240\u6709\u7684\u591a\u5bf9\u591a\u5173\u7cfb\uff1a\n>>> g1.members.clear()\n>>> p1.group_set.all()\n<QuerySet []>\n>>> p2.group_set.all()\n<QuerySet [<Group: \u75af\u72c2\u7684\u5522\u5450\u4e50\u961f>]><\/code><\/pre>\n
*4\u3001\u81ea\u5173\u8054*<\/em><\/strong><\/p>\n
\u81ea\u5df1\u8ddf\u81ea\u5df1\u5173\u8054\uff0c\u9ed8\u8ba4\u662f\u6570\u636e\u662f\u5bf9\u79f0\u7684<\/p>\n
class Person(models.Model):\n    id=models.AutoField(primary_key=True)\n    name=models.CharField(max_length=30,null=True)\n    friends=models.ManyToManyField('self')\n\n>>> obj1=Person(name='egon')\n>>> obj2=Person(name='tom')\n>>> obj1.save()\n>>> obj2.save()\n>>> obj1.friends.add(obj2)\n\u670b\u53cb\u5173\u7cfb\u8868\u91cc\u4f1a\u5bf9\u79f0\u7740\uff0c\u6709\u4e24\u6761\u8bb0\u5f55\n\n\u6570\u636e\u5e93\u8868\u91ccapp01_person_friends\nid       from_person_id          to_person_id\n1                1                    2\n2                2                    1\n\n\u53ef\u4ee5\u6307\u5b9a\u53c2\u6570symmetrical=False\uff0c\u6765\u5173\u95ed\u5bf9\u79f0\nclass Person(models.Model):\n    id=models.AutoField(primary_key=True)\n    name=models.CharField(max_length=30,null=True)\n    friends=models.ManyToManyField('self',symmetrical=False)\n\n\u5982\u679c\u662f\u81ea\u5173\u8054\uff0c \u5e76\u4e14\u5b9a\u5236\u4e86\u4e2d\u95f4\u6a21\u578b\uff0c\u90a3\u4e48\u5fc5\u987b\u8bbe\u7f6esymmetrical=False\nclass Person(models.Model):\n    id=models.AutoField(primary_key=True)\n    name=models.CharField(max_length=30,null=True)\n    friends=models.ManyToManyField('self',through='PersonShip',symmetrical=False,through_fields=('t_friend','f_friend'))\n\nclass PersonShip(models.Model):\n    create_time=models.DateTimeField(auto_now_add=True)\n    f_friend=models.ForeignKey('Person',on_delete=models.CASCADE,)\n    t_friend=models.ForeignKey('Person',on_delete=models.CASCADE,related_name='aaaa')<\/code><\/pre>\n
\u4e09\u3001\u8868\u5173\u7cfb\u4e4b\u4e00\u5bf9\u4e00<\/h2>\n
*1\u3001\u4e00\u5bf9\u4e00\u5173\u7cfb*<\/em><\/strong><\/p>\n
\u5b9a\u4e49\u4e00\u5bf9\u4e00\u5173\u7cfb\uff0c\u9700\u8981\u4f7f\u7528OneToOneField.\u60a8\u540c\u6837\u53ef\u4ee5\u50cf\u4f7f\u7528\u4efb\u4f55\u5176\u4ed6\u5b57\u6bb5\u7c7b\u578b\u4e00\u6837\u53bb\u4f7f\u7528\u5b83\uff1a\u5c06\u5176\u4f5c\u4e3a\u6a21\u578b\u7684\u7c7b\u5c5e\u6027<\/p>\n
# OneToOneField\u53c2\u6570\n1\u3001to\uff1a\u6240\u5173\u8054\u7684\u6a21\u578b\u7c7b\n\n2\u3001to_field: \u8bbe\u7f6e\u8981\u5173\u8054\u8868\u7684\u5b57\u6bb5\n\n3\u3001on_delete\uff1a\u540cForeignKey<\/code><\/pre>\n
\u793a\u4f8b<\/p>\n
class visitor(models.Model):  # \u8bbf\u5ba2\n    pass\n\nclass Customer(models.Model):  # \u5ba2\u6237\n    visitor = models.OneToOneField(to='visitor', on_delete=models.CASCADE)\n    # \u4e5f\u53ef\u4ee5\u5199\u6210\n    # visitor = models.ForeignKey(to='visitor', unique=True, on_delete=models.CASCADE)<\/code><\/pre>\n
OneToOneField\u5c31\u662f\u5728ForeignKey\u7684\u57fa\u7840\u4e0a\u8bbe\u7f6e\u4e00\u4e2aunique=True,\u53ea\u4e0d\u8fc7\u53cd\u5411\u67e5\u8be2\u51fa\u7684\u7ed3\u679c\u5c31\u4e00\u4e2a\u5bf9\u8c61\uff0c\u56e0\u4e3a\u672c\u8d28\u4e0eForeignKey\u7c7b\u4f3c\uff0c\u6240\u4ee5\u6ce8\u610fon_delete\u4e5f\u662f\u8981\u52a0\u7684\u3002<\/p>\n
ps\uff1a\u56e0\u4e3a\u4e00\u5bf9\u4e00\u6ee1\u8db3\u201c\u662f\u201d\u7684\u5173\u7cfb\uff0c\u6240\u4ee5\u4e8b\u5b9e\u4e0a\uff0c\u4e3a\u4e86\u5904\u7406\u8fd9\u4e2a\u95ee\u9898\uff0c\u4f60\u901a\u5e38\u4f1a\u4f7f\u7528\u7ee7\u627f\uff0c\u5176\u4e2d\u5c31\u5df2\u7ecf\u5305\u542b\u4e00\u4e2a\u9690\u542b\u7684\u4e00\u5bf9\u4e00\u5173\u7cfb\uff09\u3002<\/p>\n
*2\u3001\u60f0\u6027\u5173\u7cfb*<\/em><\/strong><\/p>\n
\u540cForeignKey\u4e00\u6837<\/p>\n
*3\u3001\u81ea\u5173\u8054*<\/em><\/strong><\/p>\n
\u540cForeignKey\u4e00\u6837<\/p>\n
*4\u3001\u5176\u4ed6*<\/em><\/strong><\/p>\n
*# \u6ce8\u610f*
\n<\/em>\u73b0\u5728\u53ef\u4ee5\u5728\u4e00\u4e2a\u6a21\u578b\u4e0a\u6709\u591a\u4e2aOneToOneField\u7c7b\u578b\u7684\u5b57\u6bb5\u3002
\n<\/em>\u5728\u4ee5\u524d\u7684\u7248\u672c\u4e2d\uff0cOneToOneField \u5b57\u6bb5\u4f1a\u81ea\u52a8\u53d8\u6210\u6a21\u578b \u7684\u4e3b\u952e\u3002 \u4e0d\u8fc7\u73b0\u5728\u5df2\u7ecf\u4e0d\u8fd9\u4e48\u505a\u4e86(\u4e0d\u8fc7\u8981\u662f\u4f60\u613f\u610f\u7684\u8bdd\uff0c\u4f60\u4ecd\u53ef\u4ee5\u4f20\u9012 primary_key\u53c2\u6570\u6765\u521b\u5efa\u4e3b\u952e\u5b57\u6bb5)\u3002 \u6240\u4ee5\u4e00\u4e2a\u6a21\u578b\u4e2d\u53ef\u4ee5\u6709\u591a\u4e2aOneToOneField \u5b57\u6bb5\u3002<\/p>\n
\u56db\u3001\u8de8\u6587\u4ef6\u5efa\u7acb\u6a21\u578b\u5173\u7cfb<\/h2>\n
\u4e0e\u53e6\u5916\u4e00\u4e2aapp\u4e2d\u7684\u6a21\u578b\u5efa\u7acb\u5173\u8054\u662f\u5b8c\u5168\u53ef\u4ee5\u7684\uff0c\u5982\u4f55\u5b9e\u73b0\u5462\uff1f\n\u5728\u6211\u4eec\u5b9a\u4e49\u6a21\u578b\u7684\u6587\u4ef6\u9876\u90e8\u5bfc\u5165\u5176\u4ed6app\u7684\u6a21\u578b\uff0c\u7136\u540e\u5728\u9700\u8981\u7684\u5730\u65b9\u8fdb\u884c\u5173\u8054\u5373\u53ef\uff0c\u5982\u4e0b\n# app01\u4e0b\u7684models.py\nfrom django.db import models\nfrom app02.models import ZipCode\n\nclass Restaurant(models.Model):\n    # ...\n    zip_code = models.ForeignKey(\n        ZipCode,\n        on_delete=models.SET_NULL,\n        blank=True,\n        null=True,\n    )<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
\u5efa\u7acb\u8868\u5173\u7cfb \u663e\u7136\uff0c\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7684\u5f3a\u5927\u4e4b\u5904\u5c31\u5728\u4e8e\u5c06\u8868\u76f8\u4e92\u5173\u8054\uff0cDjango\u63d0\u4f9b\u4e86\u5b9a\u4e49\u4e09\u79cd\u6700\u5e38\u89c1\u7684\u6570\u636e\u5e93\u5173\u7cfb\u7c7b\u578b\u7684 […]<\/p>\n","protected":false},"author":3,"featured_media":6792,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[3,405],"tags":[],"_links":{"self":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/6182"}],"collection":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6182"}],"version-history":[{"count":0,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/6182\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/media\/6792"}],"wp:attachment":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6182"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6182"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6182"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}