如何限制Django管理员的下拉列表 [英] How to restrict dropdown in Django admin

问题描述

$ A code code code code code code $ C pre>

我有上面的代码 - 如何确保在A的管理员下的下拉菜单中，对于外国，我只能提供独特的选择？这只是为了防止用户违反唯一性约束并显示管理错误消息。

解决方案

请查看ModelAdmin。 formfield_for_foreignkey（） here 。缺点是不得不诉诸于 raw SQL 。

  class AModelAdmin（admin.ModelAdmin）：
 def formfield_for_foreignkey（self，db_field，request，* * kwargs）
如果db_field.name ==foreign：
 kwargs [queryset] = B.objects.raw（'SELECT * FROM myapp_a其中不存在（select id from myapp_b where b .id = a.foreign_id'）
 return super（AModelAdmin，self）.formfield_for_foreignkey（db_field，request，** kwargs）
  

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class A(models.Model):
    foreign = models.ForeignKey(B, unique=True)

I have the code above - how can I ensure that in the dropdown under A's Admin, for 'foreign', I am only presented with unique choices? This is just to prevent a user violating the uniqueness constraint and being presenting with the admin error message.

解决方案

Please look at ModelAdmin.formfield_for_foreignkey() here. The downside is having to resort to raw SQL.

class AModelAdmin(admin.ModelAdmin):
def formfield_for_foreignkey(self, db_field, request, **kwargs):
    if db_field.name == "foreign":
        kwargs["queryset"] = B.objects.raw('SELECT * FROM myapp_a where not exists (select id from myapp_b where b.id=a.foreign_id')
    return super(AModelAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)

IMHO "non-null non-blank unique FKs" looks like good opportunity to rethink your modeling - may be merging two models. Everytime I found myself struggling too hard in Django I was trying to do something naive.

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