[Django]-How can I set the field unique in django?

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

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

If you are looking for a unique case insensitive, then do this.

example "my NamE is John" and "MY naME is jOHN" should match and will not work to have 2,

because if you write "my NamE is John" it will become "My name is john".

and "MY naME is jOHN" will also become "My name is john".

models.py

1. add this code to the top.

capitalizeFirstChar = lambda s: s[:1].upper() + s[1:]

2. Then here is an example how to use it.

    class MyModel(models.Model):
        name = models.CharField(max_length=255, unique=True)
    
        def __str__(self):
            return self.name
    
# The save method to convert your text "MY naME is jOHN" to "My name is john"

        def save(self, force_insert=False, force_update=False):
            self.name = self.name.lower()
            self.name = capitalizeFirstChar(self.name)
    
            # If the name already exists
            if not Category.objects.filter(name__iexact=self.name).exists():
                super(Category, self).save(force_insert, force_update)

This solution sucks if you don’t want the characters to change in capitalisation.