創建一個新模型，其中包含當前現有模型的所有字段

Question

我正在使用我的django應用程序模型Player。

class Player(models.Model): 
    """ player model """ 
    name = models.CharField(max_length=100, null=True, blank=True) 
    date_created = models.DateTimeField(auto_now_add=True) 
    last_updated = models.DateTimeField(auto_now=True) 
    hash = models.CharField(max_length=128, null=True, blank=True) 
    bookmark_url = models.CharField(max_length=300, null=True, blank=True) 

按我的要求，我需要建立一個新的模式BookmarkPlayer這將有Player模型的各個領域。

現在我有兩件事情在我的腦海裏這樣做。

1. 我可以爲BookmarkPlayer模型擴展Player類。

 
    class BookmarkPlayer(Player): 
     """ just a bookmark player""" 
     class Meta: 
      app_label = "core" 

我可以定義成BookmarkPlayer模型播放器模型的所有字段。

 
    class BookmarkPlayer(models.Model): 
      """ bookmark player model """ 
      name = models.CharField(max_length=100, null=True, blank=True) 
      date_created = models.DateTimeField(auto_now_add=True) 
      last_updated = models.DateTimeField(auto_now=True) 
      hash = models.CharField(max_length=128, null=True, blank=True) 
      bookmark_url = models.CharField(max_length=300, null=True, blank=True) 

我只是想知道哪種方式是更好地做到這一點。請分享給我的，如果有另一種好辦法。

更新問題

Knbb的主意，以創建一個基類是有趣的，但我面臨的問題，我的模型，該模型已存在導入數據庫之一。

我的實際型號：更改後

 
class Address(models.Model): 
    address = models.TextField(null=True, blank=True) 


class Site(models.Model): 
    domain = models.CharField(max_length=200) 


class Player(models.Model): 
    # ... other fields 
    shipping_address = models.ForeignKey(Address, related_name='shipping') 
    billing_address = models.ForeignKey(Address, related_name='billing') 
    created_at = models.DateTimeField(auto_now_add=True) 
    updated_at = models.DateTimeField(auto_now_add=True) 
    site = models.ManyToManyField(Site, null=True, blank=True) 

    class Meta: 
     abstract = True 

型號：

 
class Address(models.Model): 
    address = models.TextField(null=True, blank=True) 


class Site(models.Model): 
    domain = models.CharField(max_length=200) 


class BasePlayer(models.Model): 
    # .. other fields 
    shipping_address = models.ForeignKey(Address, related_name='shipping') 
    billing_address = models.ForeignKey(Address, related_name='billing') 
    created_at = models.DateTimeField(auto_now_add=True) 
    updated_at = models.DateTimeField(auto_now_add=True) 
    site = models.ManyToManyField(Site, null=True, blank=True) 

    class Meta: 
     abstract = True 

class Player(BasePlayer): 
    class Meta: 
     app_label = 'core' 


class BookmarkPlayer(BasePlayer): 
    class Meta: 
     app_label = 'core' 

當我運行我的Django的服務器我得到如下的錯誤了這些改變後。

 
django.core.management.base.CommandError: One or more models did not validate: 
core.test1: Accessor for field 'shipping_address' clashes with related field 'Address.shipping'. Add a related_name argument to the definition for 'shipping_address'. 
core.test1: Reverse query name for field 'shipping_address' clashes with related field 'Address.shipping'. Add a related_name argument to the definition for 'shipping_address'. 
core.test1: Accessor for field 'billing_address' clashes with related field 'Address.billing'. Add a related_name argument to the definition for 'billing_address'. 
core.test1: Reverse query name for field 'billing_address' clashes with related field 'Address.billing'. Add a related_name argument to the definition for 'billing_address'. 
core.test2: Accessor for field 'shipping_address' clashes with related field 'Address.shipping'. Add a related_name argument to the definition for 'shipping_address'. 
core.test2: Reverse query name for field 'shipping_address' clashes with related field 'Address.shipping'. Add a related_name argument to the definition for 'shipping_address'. 
core.test2: Accessor for field 'billing_address' clashes with related field 'Address.billing'. Add a related_name argument to the definition for 'billing_address'. 
core.test2: Reverse query name for field 'billing_address' clashes with related field 'Address.billing'. Add a related_name argument to the definition for 'billing_address' 

答：
最後我得到的回答，如果我們正在使用一個ForeignKey或ManyToManyField的related_name屬性爲抽象模型。
這通常會導致抽象基類中的問題，因爲此類中的字段包含在每個子類中，每次屬性（包括related_name）的值完全相同。
要解決此問題，當您在抽象基類（僅）中使用related_name時，部分名稱應包含'％（app_label）s'和'％（class）s'。
https://docs.djangoproject.com/en/dev/topics/db/models/#abstract-base-classes
現在我BasePlayer模型

 
class BasePlayer(models.Model): 
    # .. other fields 
    shipping_address = models.ForeignKey(Address, related_name='%(app_label)s_%(class)s_shipping') 
    billing_address = models.ForeignKey(Address, related_name='%(app_label)s_%(class)s_billing') 
    created_at = models.DateTimeField(auto_now_add=True) 
    updated_at = models.DateTimeField(auto_now_add=True) 
    site = models.ManyToManyField(Site, null=True, blank=True) 

    class Meta: 
     abstract = True 

Answer 1

如果您BookmarkPlayer需要同樣的數據，但在不同的表，抽象基地模式是最好的一段路要走：

class BasePlayer(models.Model): 
    name = models.CharField(max_length=100, null=True, blank=True) 
    date_created = models.DateTimeField(auto_now_add=True) 
    last_updated = models.DateTimeField(auto_now=True) 
    hash = models.CharField(max_length=128, null=True, blank=True) 
    bookmark_url = models.CharField(max_length=300, null=True, blank=True) 

    class Meta: 
     abstract = True 

class Player(BasePlayer): 
    """ player model """ 
    pass 

class BookmarkPlayer(BasePlayer): 
    """ bookmark player model """ 
    pass 

這樣一來，既Player和BookmarkPlayer繼承了BasePlayer模型中的領域，但由於BasePlayer是抽象的，該模型是完全解耦的。

在另一方面，多表繼承仍保存字段一個表，但是有一個隱含的OneToOneField添加額外的表爲BookmarkPlayer到Player表。

Answer 2

大約有模型繼承這裏一些好的信息： https://docs.djangoproject.com/en/1.7/topics/db/models/#model-inheritance

選項2將引入重複，這始終是壞的。如果BookmarkPlayer不會有任何新字段，只有不同的方法，我建議您使用鏈接中描述的「代理模型」選項，因爲您不需要BookmarkPlayer在數據庫中擁有自己的表。

如果它需要它自己的表，「多表inhertiance」是的路要走，這將是選項1你的問題