[英]How can you add to a ManyToManyField extension of the default Django User model?
[英]How to set default value for a ManyToManyField in Django
编辑更新的 models.py models.py:
from django.db import models
from django.db.models.signals import post_save
from django.dispatch import receiver
class Department(models.Model):
departmentName = models.CharField(max_length=100)
def __str__(self):
return self.departmentName
class Designation(models.Model):
designationName = models.CharField(max_length=100, null=True)
def __str__(self):
return self.designationName
class Employee(models.Model):
name = models.CharField(max_length=100)
email = models.EmailField(unique=True, blank=False)
department = models.ManyToManyField(Department, blank=True)
designation = models.ForeignKey(Designation, null=True, on_delete=models.SET_NULL)
def __str__(self):
return self.name
def departments(self):
return ",".join([d.departmentName for d in self.department.all()])
#Using post receiver signal as suggested by @Daniel in answer and comments
@receiver(post_save, sender=Employee, dispatch_uid='set_department')
def SetDefaultDeparment(**kwargs):
employee = kwargs['instance']
if not employee.department.all():
resource_pool = Department.objects.get(departmentName="RP")
employee.department.add(resource_pool)
employee.save()
我的查询/要求:员工和部门由 M2M 链接。 我设置 blank=True 来克服没有选择部门的表单验证。 (null=True 似乎不适用于 M2M)
比方说,
场景一:新建Emp时,如果没有提供department,默认设置为RP(Resource pool)。
场景二:现有Emp来自HR部门; 假设由于某种原因 HR 部门被删除或 Emp 被踢出,现在 Emp 没有部门链接到它,它应该默认移动到 RP(资源池)!!
如何在 Django 中安排默认部门- RP,以便两种情况都通过?
提前致谢:)
决斗
正如这里所建议的 The right way to set the default value of a ManyToMany field in django ,你有几个选择。
以下是如何通过覆盖保存方法来做到这一点:
class Employee(models.Model):
...
def save(self):
# set department if field is empty:
if not self.department.all():
# get the resource pool department:
resource_pool = Department.objects.get(name='Resource Pool')
# add to instance:
self.department.add(resource_pool)
super(Employee, self).save(*args, **kwargs)
以下是使用 post_save 接收器的方法:
from django.db.models.signals import post_save
from django.dispatch import receiver
# this decorator will execute the function after an Employee is saved:
@receiver(post_save, sender=Employee, dispatch_uid='set_department')
def SetDefaultDeparment(**kwargs):
''' sets a default department for an Employee where needed '''
# unpack kwargs:
employee = kwargs['instance']
# set department if field is empty:
if not employee.department.all():
# get the resource pool department:
resource_pool = Department.objects.get(name='Resource Pool')
# add to instance:
employee.department.add(resource_pool)
employee.save()
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