在运行时更改模型字段

Question

我有一些模型：

from salesforce.models import SalesforceModel

class Task(SalesforceModel):
    card = models.CharField(max_length=32)
    who = models.ForeignKey(Lead) # here may be Lead or Contact model ID

还有一些更新数据的功能：

def set_contact(contact):
    ...
    # Trying to change
    Task.who = models.ForeignKey(Contact)
    # Or so:
    Task._meta.get_field('who').to = Contact
    task = Task.objects.get(...)
    task.who = contact

当然 django 不允许更改值。

ValueError: Cannot assign "Contact: Some Contact": "Task.who" must bea "Lead" instance.

Answer 1

Django 在运行时构建它的模型，之后不允许您更改它们。

你看过django_polymorphic:

from polymorphic import PolymorphicModel

class ContactBase(PolymorphicModel):
    ...

class Contact(ContactBase):
    ...

class Lead(ContactBase):
    ...

class Task(models.Model):
    card = models.CharField(max_length=32)
    who = models.ForeignKey(ContactBase)

或者Django's generic foreign key:

from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType

class Task(models.Model):
    card = models.CharField(max_length=32)
    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey('content_type', 'object_id')

这些解决方案中的任何一个都允许您将多个模型附加到 Task，但我发现多态路由清理器可以使用。