How can I set the field unique in django?

Question

I have a model class:

class PysicalServer(models.Model):

    serial_number = models.CharField(max_length=64)  # I want to add the unique
    name = models.CharField(max_length=16)

I know use the primary_key can set unique, but the serial_number is not my id field, I can not use the primary_key, is there other property I can set field unique?

Answer 1

Just add unique=True in the field, so:

serial_number = models.CharField(max_length=64, unique=True)

Refer docs for more information.

Answer 2

The key word unique=True makes the title CharField unique.

class Book(models.Model):
    title= models.CharField(max_length=300, unique=True)

    def __str__(self):
        return self.title

http://www.learningaboutelectronics.com/Articles/How-to-make-a-database-table-field-unique-in-Django.php

Answer 3

As mentioned by the other stackoverflowers above, you can use unique=True. but mind you that this won't work if you want to set a joined unique constraint. For example, if you want a combination of fields to be unique, then you should use models.UniqueConstraint as seen below

class Book(models.Model):
    title = models.CharField(max_length=300)
    sub_title = models.CharField(max_length=300)

    class Meta:
        constraints = [
            models.UniqueConstraint(fields=['title', 'sub_title'], name="%(app_label)s_%(class)s_unique")
        ]

    def __str__(self):
        return self.title