HelloDjango 第 03 篇：创建 Django 博客的数据库模型

• 2019 年 10 月 3 日
• 筆記

???????????????? HelloGitHub-Team ??

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??????????????????????????????????????????????????????????????????????????????????????????django ????????????????????

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????????????????????????????????????? 3 ??????????????????????????????????????????

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????????????????????????????????????????????????????????????????????????????????????????????? django ???????? django ????????????????????????django ?????????????? Python ??????????? Python ???????django ?? Python ????????????????????????????? django ???????? ORM?Object Relational Mapping????

????????????django ?????????

blog/models.py    from django.db import models    class Category(models.Model):      name = models.CharField(max_length=100)

Category ??????? Python ?????? models.Model ????? Category ?Category ?????? name??? models.CharField ??????

???django ?????????????????????????????? category ?????????????? name?????? id??????????? django ?????????????? Python ?????????????????? Python ????????????????????????????????????

???? 3 ???????Post?????Category??????Tag??????????????? Python ???????????????? models.py ???????????????????????????????????????????????????????????????

blog/models.py    from django.db import models  from django.contrib.auth.models import User      class Category(models.Model):      """      django ???????? models.Model ??      Category ??????????? name ?????      CharField ?????? name ??????CharField ?????      CharField ? max_length ??????????????????????????????      ?? django ???????????????????????? DateTimeField????? IntegerField ???      django ?????????????      https://docs.djangoproject.com/en/2.2/ref/models/fields/#field-types      """      name = models.CharField(max_length=100)      class Tag(models.Model):      """      ?? Tag ??????? Category ???      ????????? models.Model ??      """      name = models.CharField(max_length=100)      class Post(models.Model):      """      ?????????????????????????      """        # ????      title = models.CharField(max_length=70)        # ?????????? TextField?      # ????????????? CharField????????????????????????? TextField ????????      body = models.TextField()        # ????????????????????????????????? DateTimeField ???      created_time = models.DateTimeField()      modified_time = models.DateTimeField()        # ???????????????????? CharField ??????????????????      # ?? CharField ? blank=True ?????????????      excerpt = models.CharField(max_length=200, blank=True)        # ??????????????????????????      # ???????????????????????????????????????????????      # ???????????????????????????????????????? ForeignKey???      # ?????????? django 2.0 ???ForeignKey ?????? on_delete ??????????      # ??????????????????????????????????????????????????     # ?? models.CASCADE ??????????      # ?????????????????????????????????????????      # ManyToManyField??????????????      # ???????????????????? tags ??? blank=True?      # ???? ForeignKey?ManyToManyField ??????????????????????      # https://docs.djangoproject.com/en/2.2/topics/db/models/#relationships      category = models.ForeignKey(Category, on_delete=models.CASCADE)      tags = models.ManyToManyField(Tag, blank=True)        # ??????? User ?? django.contrib.auth.models ????      # django.contrib.auth ? django ??????????????????????????User ?      # django ?????????????      # ?????? ForeignKey ???? User ??????      # ??????????????????????????????????????????????      # Category ???      author = models.ForeignKey(User, on_delete=models.CASCADE)

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??? Category ? Tag ???????? models.Model ???? django ????Category ? Tag ?????name ???????????????????????????????????????? CharField ??? name ???????? max_length ????? name ????????????????????????????? CharField ?django ??????????????????????? DateTimeField????? IntegerField ???

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????????????????????????????????????????? django ???? ????????? ???????????????????????

Post ?????????? models.Model ????????????????????????????????

• title???????????? CharField???????? max_length = 70?

• body??????????? TextField?????????????? CharField????????????????????????? TextField ????????

• created_time ? modified_time????????????????????????????????? DateTimeField ?????

• excerpt????????????????????? CharField ???????????????????? CharField ? blank=True ?????????????

• category ? tags????????????????????????????????????????????????????????????????????????????????????????????????????????????? ForeignKey????????????? django 2.0 ???ForeignKey ?????? on_delete ?????????????????????????????????????????????????????????????? models.CASCADE ??????????

  ????????????????????????????????????????? ManyToManyField?????????????????????????????????? tags ??? blank=True?

• author???????? User ?? django.contrib.auth.models ????django.contrib.auth ? django ???????????????????????????? User ? django ????????????????????? Category ????????????? ForeignKey ???? User???????????????????????????????????????????????????? Category ???

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???????????????????ForeignKey? ManyToManyField?

ForeignKey

ForeignKey ????????????????????????????????????????????????????????????????????????????????

?????????????????????? ?? ID ????????????????????????????????? ID ???????????? ID ?????????????????????????? 1?2?3 ????? ID ?? 1???? ID ? 1 ????? django????? 1?2?3 ???? django????? 4 ???? Python?

??????????????????????????? ID ????????????? django ??? ID ? 1?????? ID ? 1 ?????? 1?2?3????? django ?? 3 ????

?????????????????????????????????????????????????? django ???????

ManyToManyField

ManyToManyField ???????????????????????????????????????????????????????????????????????????

???????????????????????????????? ?? ID ????????????????????????????????? ID ? 1 ???????? ?? ID ? 1 ???????? ?? ID ? 2 ??????? 1 ????? 1?django ???????? 2?Python ???

????? ID ? 1 ???????? ?? ID ? 1 ???????? ?? ID ? 2 ??????? 1?django ?????????

?????????????????????????????????????????????????? django ???????

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• django ForeignKey ??
• django ForeignKey ????
• django ManyToManyField ??
• django ManyToManyField ????

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