django模型减少重复代码

Question

这是我的 django 模型
因为我有ProjectsArchive 和StatusArchive 用于保存历史数据
您可以看到许多字段是重复的
我想知道如何减少重复代码使代码简单

class Projects(models.Model):
    title      = models.CharField(max_length=255, blank=True)
    link       = models.CharField(max_length=300, blank=True)
    state      = models.CharField(max_length=30, blank=True)
    update_at  = models.DateTimeField(auto_now=True, blank=True, null=True)
    ....

class ProjectsArchive(models.Model):
    title      = models.CharField(max_length=255, blank=True)
    link       = models.CharField(max_length=300, blank=True)
    state      = models.CharField(max_length=30, blank=True)
    update_at  = models.DateTimeField(auto_now=True, blank=True, null=True) 
    ....

class Status(models.Model):
    project             = models.ForeignKey(Projects, null = True, blank = True)
    state               = models.CharField(max_length=255, blank=True)
    crawl_update_at     = models.DateTimeField(auto_now=True, blank=True, null=True)    
    ....
class StatusArchive(models.Model):
    project             = models.ForeignKey(ProjectsArchive, null = True, blank = True)
    state               = models.CharField(max_length=255, blank=True)
    crawl_update_at     = models.DateTimeField(auto_now=True, blank=True, null=True)  
    ....

Answer 1

您可以创建一个 CommonModel，您可以在其中放置冗余字段，然后您想在其中使用它们的任何模型都继承 CommonModel 而不是 models.Model。

class CommonModel(models.Model):
    class Meta:
        abstract = True

    title      = models.CharField(max_length=255, blank=True)
    link       = models.CharField(max_length=300, blank=True)
    state      = models.CharField(max_length=30, blank=True)
    update_at  = models.DateTimeField(auto_now=True, blank=True, null=True)

class ProjectArchive(CommonModel):
      any_new_field_you_want_to_add

Answer 2

您可以参考这里：Abstract base classes

根据你的问题，我会这样做：

class BasicInfo(models.Model):
    title      = models.CharField(max_length=255, blank=True)
    link       = models.CharField(max_length=300, blank=True)
    state      = models.CharField(max_length=30, blank=True)
    update_at  = models.DateTimeField(auto_now=True, blank=True, null=True) 

    class Meta:
        abstract = True

class Projects(BasicInfo):
    ....

class ProjectsArchive(BasicInfo):
    ....

完成BasicInfo后，您可以重复使用title、link、state和update_at。

但是我们可以为Status 和StatusArchive 创建包含state 和crawl_update_at 的通用模型。

class StatusInfo(models.Model):
    state               = models.CharField(max_length=255, blank=True)
    crawl_update_at     = models.DateTimeField(auto_now=True, blank=True, null=True) 

    class Meta:
        abstract = True

class Status(StatusInfo):
    project             = models.ForeignKey(Projects, null = True, blank = True)
    ....

class StatusArchive(StatusInfo):
    project             = models.ForeignKey(ProjectsArchive, null = True, blank = True)
    ...

Answer 3

您正在寻找的是抽象元类。

https://docs.djangoproject.com/en/1.8/topics/db/models/

class ProjectTemplate(models.Model):
    title      = models.CharField(max_length=255, blank=True)
    link       = models.CharField(max_length=300, blank=True)
    state      = models.CharField(max_length=30, blank=True)
    update_at  = models.DateTimeField(auto_now=True, blank=True, null=True)
    ....

    class Meta:
        abstract = True

class Projects(ProjectTemplate):
    pass


class ProjectsArchive(ProjectTemplate):
    pass

Answer 4

你可以使用继承。 请看以下链接

django abstract models versus regular inheritance

还有关于模型的 django 文档（看看抽象基类）

https://docs.djangoproject.com/en/1.8/topics/db/models/