how to properly define a ManyToMany field in the models.py file

问题

In my Django app I have the following models.py:

from django.db import models
import datetime

class Job(models.Model):
    name = models.CharField(max_length = 250, null = False)
    user = models.CharField(max_length = 30, null = False)
    command = models.CharField(max_length = 1000, null = False)
    whenToRun = models.DateTimeField('Run Date', null = False)
    output = models.CharField(max_length = 100000, null = True)

class Host(models.Model):
    jobs = models.ManyToManyField(Job, blank = True)
    name = models.CharField(max_length = 100, null = False)
    hasRun = models.BooleanField(default = False)

I added the jobs assignment in the Host class with guidance from https://docs.djangoproject.com/en/dev/topics/db/examples/many_to_many/. I was able to add Hosts in with no problem (from the admin page) but when I tried to add in a Job I got the following error:

Exception at /admin/Minion/job/add
<class 'Minion.models.Host'> has no ForeignKey to <class 'Minion.models.Job'>

I tried to add a ManyToManyField assignment to the Job class as well but it told me that the name Host was undefined. Does anyone know what I can do to make this field function properly? Thanks in advance for any help.

回答1:

You need to declare inlines for ManyToMany in admin.py

Check the documentation for how to declare inlines

Something like this:

class JobInline(admin.TabularInline):
     model = Host.jobs.through

来源：https://stackoverflow.com/questions/17277772/how-to-properly-define-a-manytomany-field-in-the-models-py-file

标签

python

django

many-to-many

models