Django ManyToMany字段不是在模型中创建的

问题描述

  class Teacher（个人资料）：
 class Meta：
 db_table ='teacher'
 
 user = models.OneToOneField（User，
 unique = True，
 verbose_name = _（'user'），
 related_name = 'teacher'）
 
 home_address = models.CharField（_（'home_address'），max_length = 255，blank = True）
 home_phone = models.CharField（_（'home_phone' max_length = 30，blank = True）
 cell_phone = models.CharField（_（'cell_phone'），max_length = 30，blank = True）
 experience = models.IntegerField（default = 0）
 summary = models.TextField（_（'summary'），max_length = 500，blank = True）
 subjects = models.ManyToManyField（Subjects，through ='SubjectsIntermediate'）
  

当我执行 manage.py syncdb 时，它会创建老师表，除了字段主题之外的所有字段。为什么没有创建主题字段？

解决方案

因为ManyToMany不是一个字段，至少不是一个作为数据库列存在的字段。这是与链接表的关系。您会发现，创建了一个名为 myapp_teacher_subjects 的表，其中包含老师和主题的外键。

Here is my Model for Teacher class.

class Teacher(Profile):
    class Meta:
        db_table = 'teacher'

    user = models.OneToOneField(User,
                                unique=True,
                                verbose_name=_('user'),
                                related_name='teacher')

    home_address =  models.CharField(_('home_address'), max_length=255, blank=True)
    home_phone =  models.CharField(_('home_phone'), max_length=30, blank=True)
    cell_phone =  models.CharField(_('cell_phone'), max_length=30, blank=True)
    experience =  models.IntegerField(default = 0)
    summary =  models.TextField(_('summary'), max_length=500, blank=True)
    subjects = models.ManyToManyField(Subjects, through='SubjectsIntermediate')

When i execute the manage.py syncdb it does creates the teacher table with all fields except for field subjects. Why the subjects field is not created??

解决方案

Because a ManyToMany isn't a field, at least not one that exists as a database column. It's a relationship with a linking table. You'll find that a table named myapp_teacher_subjects has been created, with foreign keys to both teacher and subjects.

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