Whether to use a through model in a M2M relationship

Question

I am adding a user's education to his userprofile. A user may have multiple entries for his education. Should I be using a basic M2M relationship, such as --

class Education(models.Model):
    school = models.CharField(max_length=100)
    class_year = models.IntegerField(max_length=4, blank=True, null=True)
    degree = models.CharField(max_length=100, blank=True, null=True)

class UserProfile(models.Model):
    user = models.ForeignKey(User, unique=True)
    educations = models.ManyToManyField(Education)

Or should I be using a through model for this relationship? Thank you.

Answer 1

@manji is correct: Django will create a mapping table whether or not you use through.

To provide an example of why you might want to add more fields to the intermediary, or through table:
You could have a field in the through table to track whether or not that particular education represented the final school the person attended:

class Education(models.Model):
    ...

class UserProfile(models.Model):
    ...
    educations = models.ManyToManyField(Education, through='EduUsrRelation')

class EducationUserRelation(models.Model):
    education = models.ForeignKey(Education)
    user_profile = models.ForeignKey(UserProfile)
    is_last_school_attended = models.BooleanField()

Answer 2

Django will create automatically an intermediary join table to represent the ManyToMany relation between the 2 models.

If you want to add more fields to this table, provide your own table (i.e Model) via through attribute, otherwise you don't need to.