CODEWITHSUNDEEP
djangodjango-models
108
108

Reputation: 139

adding unique key to many to many field in django

I have following models

class SettingAttributes(Core):
    attribute_name = models.CharField(max_length=100)
    description = models.CharField(max_length=100)
    setting_type = models.CharField(max_length=10, choices=SETTING_TYPES)

    class Meta:
        app_label = 'core'

and 

class SettingAttrValue(Core):
    attribute_value = models.CharField(max_length=200)
    attribute_type = models.CharField(max_length=200)
    attribute = models.ForeignKey(SettingAttributes)
    user = models.ManyToManyField(User)
    avaliases = models.TextField()
    attriblob = models.BinaryField(default=None, blank=True, null=True)

    class Meta:
        app_label = 'core'

I want to add unique_together on SettingAttrValue and User. If i do this in meta class of second model django is giving me error like 'unique_together' refers to a ManyToManyField 'user', but ManyToManyFields are not permitted in 'unique_together'.

Upvotes: 1

Views: 2191

Answers (1)

Ivan
Ivan

Reputation: 2675

Add unique_together to the intermediate model:

class SettingAttrValue(Core):
    attribute_value = models.CharField(max_length=200)
    attribute_type = models.CharField(max_length=200)
    attribute = models.ForeignKey(SettingAttributes)
    user = models.ManyToManyField(User, through='UserSettingAttrValue')
    avaliases = models.TextField()
    attriblob = models.BinaryField(default=None, blank=True, null=True)

    class Meta:
        app_label = 'core'


class UserSettingAttrValue(models.Model):
    setting_attr_value = models.ForeignKey(SettingAttrValue)
    user = models.ForeignKey(User)

    class Meta:
        unique_together = ('setting_attr_value', 'user')

Upvotes: 2

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