FieldDoesNotExist: ManyToManyField has no field named None

user_1098258 0
Viewed 2104

I have two models in Django 1.8.8:

class Company(models.Model):
    name = models.CharField(max_length=200)
    members = models.ManyToManyField(User)
class Folder(models.Model):
    name = models.CharField(max_length=200)
    slug = models.SlugField(null=True, blank=True)
    company = models.ForeignKey(Company, null=True, blank=True)
    parent = models.ForeignKey("Folder", null=True, blank=True)

and when I'm doing in template

{% for user in current_folder.company.members.all %}

I sometimes (randomly after a few page's reload) get very strange error:

FieldDoesNotExist: Company_members has no field named None

I also use sqlite3 database. Anyone have idea where is a problem?

manytomanyfield django python
5 Answers
user_35449310

If you want to access a ForeignKey field from an instance you can not access it directly as you did here

{% for user in current_folder.company.members.all %}

ForeignKey field is a company so it should be

current_folder.company_set()

Note: ForeignKey returns a set of objects. In your case a set of companies. That's why it returns FieldDoesNotExist

user_127331540

In ManyToManyFields you must add the related_name parameter if you want to access the related objects. So for this case, it should be like this:

class Company(models.Model):
    name = models.CharField(max_length=200)
    members = models.ManyToManyField(User, related_name='members')
class Folder(models.Model):
    name = models.CharField(max_length=200)
    slug = models.SlugField(null=True, blank=True)
    company = models.ForeignKey(Company, null=True, blank=True)
    parent = models.ForeignKey("Folder", null=True, blank=True)
user_96031700

try adding null and blank field

members = models.ManyToManyField(user, blank=True, null=True)
user_84450010
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