Django unique=True not working

For django 1.9+
Running makemigrations then migrate applies the unique constraint to sqlite3

For django < 1.9
Since you are using django 1.5, this solution will apply.

If you added the unique=True after the table was already created, then even if you do syncdb later, the unique condition will not be added to your table.

I can confirm with sqlite3 that Django 1.5 happily saves duplicate objects with MyModel(url="blah").save() if the unique constraint does not exist in the database, which seems to contradict with the docs.

The best solution for you is to create the constraint manually in your database using this command.

ALTER TABLE MyModel_mymodel ADD UNIQUE (url);

Or if you don't mind, you can recreate your table. (Drop the table and then run syncdb.)

Running sql scripts directly on the db can be avoided. Rather add the sql execution in your migration:

from __future__ import unicode_literals
from django.db import migrations, connection


def alter_table(apps, schema_editor):
    query ="ALTER TABLE <your table> ADD UNIQUE (unique_col);"
    cursor = connection.cursor()
    cursor.execute(query)
    cursor.close()

class Migration(migrations.Migration):

    dependencies = [
        ('app', 'yourlastmigration'),
    ]

    operations = [        
        migrations.RunPython(alter_table),
    ]