blocks|key|1542167|text|class+Foo(models.Model):
++++a+=+models.CharField(max_length=42)

class+Bar(models.Model):
++++b+=+models.CharField(max_length=42)
++++a+=+models.ForeignKey(Foo,+default=lambda:+Foo.objects.get(id=1)+)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1542168|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>class Foo(models.Model):
 a = models.CharField(max_length=42)

class Bar(models.Model):
 b = models.CharField(max_length=42)
 a = models.ForeignKey(Foo, default=lambda: Foo.objects.get(id=1) )
</code></pre>

blocks|key|1542442|text|对于django+1.7或更高版本，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1542443|只需创建一个ForeignKey对象并保存它。"+default“值可以是默认链接的对象的id。|1542444|例如,|1542445|created_by+=+models.ForeignKey(User,+default=1)|code-block|syntax|javascript|1542446|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

For django 1.7 or greater, 

Just create an ForeignKey object and save it. "default" value can be the id of the the object that should be linked by default.

For example,

<pre><code>created_by = models.ForeignKey(User, default=1)
</code></pre>

blocks|key|1542285|text|这是一个适用于Django+1.7的解决方案。不是在字段定义处提供默认值，而是将其设置为null-able，但覆盖'save‘函数以在第一次填充它(当它为null时)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1542286|class+Foo(models.Model):
++++a+=+models.CharField(max_length=42)

class+Bar(models.Model):
++++b+=+models.CharField(max_length=42)
++++a+=+models.ForeignKey(Foo,+null=True)

++++def+save(self,+*args,+**kwargs):
++++++++if+self.a+is+None:++#+Set+default+reference
++++++++++++self.a+=+Foo.objects.get(id=1)
++++++++super(Bar,+self).save(*args,+**kwargs)|code-block|syntax|javascript|1542287|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here's a solution that will work in Django 1.7.
Instead of providing the default at the field definition, set it as null-able, but overide the 'save' function to fill it on the first time (while it's null):

<pre><code>class Foo(models.Model):
 a = models.CharField(max_length=42)

class Bar(models.Model):
 b = models.CharField(max_length=42)
 a = models.ForeignKey(Foo, null=True)

 def save(self, *args, **kwargs):
 if self.a is None: # Set default reference
 self.a = Foo.objects.get(id=1)
 super(Bar, self).save(*args, **kwargs)
</code></pre>

blocks|key|1327153|text|我已经完成了类似于@o_c的工作，但是我更喜欢使用get_or_create，而不仅仅是普通的pk。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1327154|class+UserSettings(models.Model):
++++name+=+models.CharField(max_length=64,+unique=True)
++++#+...+some+other+fields+

++++@staticmethod
++++def+get_default_user_settings():
++++++++user_settings,+created+=+UserSettings.objects.get_or_create(
++++++++++++name+=+'Default+settings'
++++++++)
++++++++return+user_settings

class+SiteUser(...):
++++#+...+some+other+fields

++++user_settings+=+models.ForeignKey(
++++++++to=UserSettings,+
++++++++on_delete=models.SET_NULL,+
++++++++null=True
++++)

++++def+save(self,+*args,+**kwargs):
++++++++if+self.user_settings+is+None:
++++++++++++self.user_settings+=+UserSettings.get_default_params()
++++++++super(SiteUser,+self).save(*args,+**kwargs)|code-block|syntax|javascript|1327155|entityMap^0|P|D|1B|2|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

I've done this similarly to @o_c, but I'd rather use <code>get_or_create</code> than just plain <code>pk</code>.

<pre><code>class UserSettings(models.Model):
 name = models.CharField(max_length=64, unique=True)
 # ... some other fields 

 @staticmethod
 def get_default_user_settings():
 user_settings, created = UserSettings.objects.get_or_create(
 name = 'Default settings'
 )
 return user_settings

class SiteUser(...):
 # ... some other fields

 user_settings = models.ForeignKey(
 to=UserSettings, 
 on_delete=models.SET_NULL, 
 null=True
 )

 def save(self, *args, **kwargs):
 if self.user_settings is None:
 self.user_settings = UserSettings.get_default_params()
 super(SiteUser, self).save(*args, **kwargs)
</code></pre>

blocks|key|1326976|text|如果您使用的是Django的开发版本，则可以在AdminModel上实现formfield_for_foreignkey()方法来设置默认值。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1326977|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.djangoproject.com/en/dev/ref/contrib/admin/#django.contrib.admin.ModelAdmin.formfield_for_foreignkey^0|N|A|10|Q|10|Q|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]]|E|$]]|$1|F|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

If you are using the development version of Django, you can implement the <a href="http://docs.djangoproject.com/en/dev/ref/contrib/admin/#django.contrib.admin.ModelAdmin.formfield_for_foreignkey" rel="noreferrer"><code>formfield_for_foreignkey()</code></a> method on your <code>AdminModel</code> to set a default value.

blocks|key|1327050|text|对我来说，对于Django+1.7的工作，只需要pk：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1327051|category+=+models.ForeignKey(Category,+editable=False,+default=1)|offset|length|style|CODE|1327052|但请记住，该迁移看起来像|1327053|migrations.AlterField(
++++++++++++model_name='item',
++++++++++++name='category',
++++++++++++field=models.ForeignKey(default=1,+editable=False,+to='item.Category'),
++++++++++++preserve_default=True,
++++++++),|code-block|syntax|javascript|1327054|所以，我不认为它会与动态用户pk一起工作。|1327055|entityMap^0|0|0|1T|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@$D|U|E|V|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|X|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

As for me, for Django 1.7 its work, just pk:

<code>category = models.ForeignKey(Category, editable=False, default=1)</code>

but remember, that migration looks like

<pre><code>migrations.AlterField(
 model_name='item',
 name='category',
 field=models.ForeignKey(default=1, editable=False, to='item.Category'),
 preserve_default=True,
 ),
</code></pre>

so, i don't think it's to be working with dynamic user pk.

blocks|key|1542219|text|def+get_user_default_id():
++++return+1

created_by+=+models.ForeignKey(User,+default=get_user_default_id)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1542220|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>def get_user_default_id():
 return 1

created_by = models.ForeignKey(User, default=get_user_default_id)
</code></pre>

blocks|key|1542392|text|这是对o_c的答案的轻微修改。它应该可以在数据库上节省一次命中次数。注意，在保存方法中，我使用self.a_id+=1而不是self.a+=+Foo.objects.get(id=1)。它具有相同的效果，而无需查询Foo。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1542393|class+Foo(models.Model):
++++a+=+models.CharField(max_length=42)

class+Bar(models.Model):
++++b+=+models.CharField(max_length=42)
++++a+=+models.ForeignKey(Foo,+null=True)

++++def+save(self,+*args,+**kwargs):
++++++++if+self.a+is+None:++#+Set+default+reference
++++++++++++self.a_id+=+1
++++++++super(Bar,+self).save(*args,+**kwargs)|code-block|syntax|javascript|1542394|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/users/2838311/o-c^0|3|3|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

This is a slight modification to the answer from <a href="https://stackoverflow.com/users/2838311/o-c">o_c</a>. It should save you one hit on the database. Notice in the save method I use self.a_id = 1 instead of self.a = Foo.objects.get(id=1). It has the same effect without having to query Foo.

<pre><code>class Foo(models.Model):
 a = models.CharField(max_length=42)

class Bar(models.Model):
 b = models.CharField(max_length=42)
 a = models.ForeignKey(Foo, null=True)

 def save(self, *args, **kwargs):
 if self.a is None: # Set default reference
 self.a_id = 1
 super(Bar, self).save(*args, **kwargs)
</code></pre>

blocks|key|1542502|text|使用部分函数代替lambda函数。Lambda函数不是序列化的，因此在迁移时会出现错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1542503|class+Foo(models.Model):
++++a+=+models.CharField(max_length=42)

class+Bar(models.Model):
++++b+=+models.CharField(max_length=42)
++++a+=+models.ForeignKey(Foo,+default=partial(Foo.objects.get,+id=1+))|code-block|syntax|javascript|1542504|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Instead of lambda function use partial function. Lambda function is not serialization and hence gives error in migrations. 

<pre><code>class Foo(models.Model):
 a = models.CharField(max_length=42)

class Bar(models.Model):
 b = models.CharField(max_length=42)
 a = models.ForeignKey(Foo, default=partial(Foo.objects.get, id=1 ))
</code></pre>

blocks|key|1542540|text|您应该在settings.py文件中具有与setting.AUTH_USER_MODEL相关的设置。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1542541|您可以在下面的文档中查看：|1542542|"https://docs.djangoproject.com/en/1.10/topics/auth/customizing/#substituting-a-custom-user-model“|offset|length|1542543|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/1.10/topics/auth/customizing/#substituting-a-custom-user-model^0|0|0|1|2O|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@$F|S|G|T|1|U]]|A|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]]]

You should have settings related to setting.AUTH_USER_MODEL in settings.py file.

You can look in below document:

"<a href="https://docs.djangoproject.com/en/1.10/topics/auth/customizing/#substituting-a-custom-user-model" rel="nofollow noreferrer">https://docs.djangoproject.com/en/1.10/topics/auth/customizing/#substituting-a-custom-user-model</a>"

blocks|key|1327346|text|您可以覆盖模型管理员的get_form方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1327347|admin.py|1327348|class+YourModelAdmin(admin.ModelAdmin):
++++def+get_form(self,+request,+obj=None,+**kwargs):
++++++++form+=+super(YourModelAdmin,+self).get_form(request,+obj,+**kwargs)
++++++++form.base_fields['created_by'].initial+=+request.user
++++return+form

admin.site.register(YourModel,+YourModelAdmin)|code-block|syntax|javascript|1327349|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/2.1/ref/contrib/admin/#django.contrib.admin.ModelAdmin.get_form^0|B|8|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

You can override the <a href="https://docs.djangoproject.com/en/2.1/ref/contrib/admin/#django.contrib.admin.ModelAdmin.get_form" rel="nofollow noreferrer">get_form</a> method of your model admin.

admin.py

<pre><code>class YourModelAdmin(admin.ModelAdmin):
 def get_form(self, request, obj=None, **kwargs):
 form = super(YourModelAdmin, self).get_form(request, obj, **kwargs)
 form.base_fields['created_by'].initial = request.user
 return form

admin.site.register(YourModel, YourModelAdmin)
</code></pre>

blocks|key|1327405|text|在找到更好的解决方案的所有迭代中，我发现创建一个小函数将从本质上解决任务的复杂性。因为一些解决方案已经过时，或者在较新的Django版本中不再受支持。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1327406|def+get_request_user():
++++#+or+any+complex+query+result+to+set+default+value+in+ForeignKey
++++return+request.user.id|code-block|syntax|javascript|1327407|然后，您可以将上述函数作为参数传递到ForeignKey中。|1327408|created_by+=+models.ForeignKey(User,+default=get_request_user)|1327409|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Out of all along iterations to find a better solution, I find creating a small function will resolve the complexity of task substantially. Because some of the solutions are outdated or longer supported in newer Django versions.

<pre><code>def get_request_user():
 # or any complex query result to set default value in ForeignKey
 return request.user.id
</code></pre>

Then you can pass above function as an argument in ForeignKey.

<pre><code>created_by = models.ForeignKey(User, default=get_request_user)
</code></pre>

blocks|key|1542212|text|class+table1(models.Model):
++++id+=+models.AutoField(primary_key=True)
++++agentname+=+models.CharField(max_length=20)

class+table1(models.Model):
++++id+=+models.AutoField(primary_key=True)
++++lastname+=+models.CharField(max_length=20)
++++table1+=+models.ForeignKey(Property)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1542213|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>class table1(models.Model):
 id = models.AutoField(primary_key=True)
 agentname = models.CharField(max_length=20)

class table1(models.Model):
 id = models.AutoField(primary_key=True)
 lastname = models.CharField(max_length=20)
 table1 = models.ForeignKey(Property)
</code></pre>

How can I set a default value on a ForeignKey field in a django Model or AdminModel?

Something like this (but of course this doesn't work)...

<pre><code>created_by = models.ForeignKey(User, default=request.user)
</code></pre>

I know I can 'trick' it in the view, but in terms of the AdminModel it doesn't seem possible.

How do you specify a default for a Django ForeignKey Model or AdminModel field?

数据库

Django

如何在django Model或AdminModel中的ForeignKey字段上设置默认值？像这样的东西(但这当然不起作用)……created_by = models.ForeignKey(User, default=request.user)我知道我可以在视图中“欺骗”它，但就AdminModel而言，这似乎是不可能的。

问如何为Django ForeignKey模型或AdminModel字段指定默认值？
EN

回答 13

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问如何为Django ForeignKey模型或AdminModel字段指定默认值？EN

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问如何为Django ForeignKey模型或AdminModel字段指定默认值？
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