We Keep Coding

"Unique constrainted failed" problem when running migrations

I have been tryed to change a django model by applying and running migrations but I have been getting this error django.db.utils.IntegrityError: UNIQUE constraint failed: new__startup_home_mates.user_id How can this error be fixed? I have already investigated a lot but I have found nothing that fits my situation. I have already tried to use RenameField and AlterField directly from the migrations file and it is still not working maybe I was doing it wrong.
models.py
class Mates(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE, related_name='usermates', unique=True)
users_requests = models.ManyToManyField(User, related_name="users_requests")
req_bio = models.CharField(max_length=400)
req_image = models.ImageField(upload_to='requestmates_pics', null=True, blank=True, default=False)
traceback
Traceback (most recent call last):
File "manage.py", line 21, in <module>
main()
File "manage.py", line 17, in main
execute_from_command_line(sys.argv)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\core\management\__init__.py", line 401, in execute_from_command_line
utility.execute()
File "C:\Users\USER\Envs\startup\lib\site-packages\django\core\management\__init__.py", line 395, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\core\management\base.py", line 328, in run_from_argv
self.execute(*args, **cmd_options)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\core\management\base.py", line 369, in execute
output = self.handle(*args, **options)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\core\management\base.py", line 83, in wrapped
res = handle_func(*args, **kwargs)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\core\management\commands\migrate.py", line 231, in handle
post_migrate_state = executor.migrate(
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\migrations\executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\migrations\executor.py", line 147, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\migrations\executor.py", line 245, in apply_migration
state = migration.apply(state, schema_editor)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\migrations\migration.py", line 124, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\migrations\operations\fields.py", line 249, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\sqlite3\schema.py", line 138, in alter_field
super().alter_field(model, old_field, new_field, strict=strict)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\base\schema.py", line 564, in alter_field
self._alter_field(model, old_field, new_field, old_type, new_type,
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\sqlite3\schema.py", line 360, in _alter_field
self._remake_table(model, alter_field=(old_field, new_field))
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\sqlite3\schema.py", line 283, in _remake_table
self.execute("INSERT INTO %s (%s) SELECT %s FROM %s" % (
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\base\schema.py", line 142, in execute
cursor.execute(sql, params)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\utils.py", line 100, in execute
return super().execute(sql, params)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\utils.py", line 90, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\USER\Envs\startup\lib\site-packages\django\db\backends\sqlite3\base.py", line 396, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: UNIQUE constraint failed: new__startup_home_mates.user_id
If you need to see more code please let me know:)

You may added a primary key / id with your models later, but previous database does not have it.
If you add new features to models, add default='something', or null=True,blank=True as arguments. So that old database won't need the unique constraints/value

I suspect that your problem is with your OnetoOneField with unique set to True. You should change this to a ForeignKey (and don't set Unique = True). This is so that users can have more than one mate. That is if I have correctly understood your model setup and what you are trying to achieve.
Here is a good summary of the differences between OnetoOneField and ForeignKey:
What's the difference between django OneToOneField and ForeignKey?

Django- Change Username field to BigAutoField?

I'm designing an Application where username will be an AutoIntegerField and unique.
Here's my model.
class ModelA(models.Model):
username = models.BigAutoField(primary_key=True, db_index=False)
user_id = models.UUIDField(default=uuid.uuid4, unique=True,
editable=False)
Initially, I wanted user_id to be a primary_key, but I can't create an AutoField which is not primary_key. As a result, I'd to let go off user_id as primary_key and assigned username as the primary key.
Now, when I run the migrations, it throws an error saying,
django.db.utils.ProgrammingError: operator class "varchar_pattern_ops" does not accept data type bigint
Complete StackTrace:-
Applying users.0005_auto_20180626_0914...Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/utils.py", line 65, in execute
return self.cursor.execute(sql, params)
psycopg2.ProgrammingError: operator class "varchar_pattern_ops" does not accept data type bigint
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "manage.py", line 22, in <module>
execute_from_command_line(sys.argv)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
utility.execute()
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/core/management/__init__.py", line 356, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/core/management/base.py", line 283, in run_from_argv
self.execute(*args, **cmd_options)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/core/management/base.py", line 330, in execute
output = self.handle(*args, **options)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 204, in handle
fake_initial=fake_initial,
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/migrations/executor.py", line 115, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/migrations/executor.py", line 145, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/migrations/migration.py", line 129, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/migrations/operations/fields.py", line 216, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 515, in alter_field
old_db_params, new_db_params, strict)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/postgresql/schema.py", line 112, in _alter_field
new_db_params, strict,
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 684, in _alter_field
params,
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 120, in execute
cursor.execute(sql, params)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/utils.py", line 80, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/utils.py", line 65, in execute
return self.cursor.execute(sql, params)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/utils.py", line 94, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/utils/six.py", line 685, in reraise
raise value.with_traceback(tb)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/django/db/backends/utils.py", line 65, in execute
return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: operator class "varchar_pattern_ops" does not accept data type bigint

I think the issue is that you still have an old index on your username field that clashes with the new type. The db_index=False argument has no effect because primary_key=True always generates an index.
You might be able to solve this by removing primary_key=True, creating a migration, and then re-adding it and creating another migration. Alternatively, you can do it by hand by dropping and re-creating the index. If you want to go down that path, consult this answer.
If your project is still in an early stage and you don't have any valuable data, you can take the easy way out and drop any tables related to your users app or even the complete database, delete all migrations in the users app and create them from scratch.

in my case I was connecting django to postgres at localhost pgadmin
first deleted all the migrations except default one and also in the pycache
then just run python manage.py makemigrations and python manage.py migrate in your terminal

OperationalError during django migration postgres on large tables

Sometimes during migrations in django on big tables (>50 millions rows) i receive the following error:
Traceback:
Traceback (most recent call last):
File "src/audit/manage.py", line 22, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.5/dist-packages/django/core/management/__init__.py", line 363, in execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.5/dist-packages/django/core/management/__init__.py", line 355, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python3.5/dist-packages/django/core/management/base.py", line 283, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python3.5/dist-packages/django/core/management/base.py", line 330, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python3.5/dist-packages/django/core/management/commands/migrate.py", line 204, in handle
fake_initial=fake_initial,
File "/usr/local/lib/python3.5/dist-packages/django/db/migrations/executor.py", line 115, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python3.5/dist-packages/django/db/migrations/executor.py", line 145, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python3.5/dist-packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/usr/local/lib/python3.5/dist-packages/django/db/migrations/migration.py", line 129, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/usr/local/lib/python3.5/dist-packages/django/db/migrations/operations/fields.py", line 86, in database_forwards
field,
File "/usr/local/lib/python3.5/dist-packages/django/db/backends/base/schema.py", line 439, in add_field
self.execute(sql)
File "/usr/local/lib/python3.5/dist-packages/django/db/backends/base/schema.py", line 120, in execute
cursor.execute(sql, params)
File "/usr/local/lib/python3.5/dist-packages/django/db/backends/utils.py", line 80, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/usr/local/lib/python3.5/dist-packages/django/db/backends/utils.py", line 65, in execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python3.5/dist-packages/django/db/utils.py", line 94, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/usr/local/lib/python3.5/dist-packages/django/utils/six.py", line 685, in reraise
raise value.with_traceback(tb)
File "/usr/local/lib/python3.5/dist-packages/django/db/backends/utils.py", line 65, in execute
return self.cursor.execute(sql, params)
django.db.utils.OperationalError: server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
Can you please give me advice - which postgres settings i should change in order to solve this issue?
I try set statement_timeout = 0, idle_in_transaction_session_timeout = 0 with no result.
Migration:
class Migration(migrations.Migration):
dependencies = [
('core', '0028_auto_'),
]
operations = [
migrations.AddField(
model_name='risk',
name='test3',
field=models.CharField(default='testme', max_length=50),
),
]
SQL:
BEGIN;
--
-- Add field test3 to risk
--
ALTER TABLE "core_risk" ADD COLUMN "test3" varchar(50) DEFAULT 'testme' NOT NULL;
ALTER TABLE "core_risk" ALTER COLUMN "test3" DROP DEFAULT;
COMMIT;

[Django]django.db.utils.IntegrityError

my app named mainsite
I have the table class named Weather in models.py
class Weather(models.Model):
tpr = models.CharField(max_length=5)
wet = models.CharField(max_length=5)
ur = models.CharField(max_length=5)
li = models.CharField(max_length=5)
observe_time = models.DateTimeField(default=None)
I don't want my observe_time set any deafult value
So I set to None .
I have made migrations.
when I made migrate
Then the traceback happen:
File "manage.py", line 22, in
execute_from_command_line(sys.argv)
File "C:\Users\User\Anaconda3\lib\site-packages\django\core\management__init__.py",
line 354, in execute_from_command_line
utility.execute() File "C:\Users\User\Anaconda3\lib\site-packages\django\core\management\__init__.py",
line 346, in execute
self.fetch_command(subcommand).run_from_argv(self.argv) File "C:\Users\User\Anaconda3\lib\site-packages\django\core\management\base.py",
line 394, in run_from_argv
self.execute(*args, **cmd_options) File "C:\Users\User\Anaconda3\lib\site-packages\django\core\management\base.py",
line 445, in execute
output = self.handle(*args, **options) File "C:\Users\User\Anaconda3\lib\site-packages\django\core\management\commands\migrate.py",
line 222, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial) File
"C:\Users\User\Anaconda3\lib\site-packages\django\db\migrations\executor.py",
line 110, in migrate
self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial) File
"C:\Users\User\Anaconda3\lib\site-packages\django\db\migrations\executor.py",
line 148, in apply_migration
state = migration.apply(state, schema_editor) File "C:\Users\User\Anaconda3\lib\site-packages\django\db\migrations\migration.py",
line 115, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state) File
"C:\Users\User\Anaconda3\lib\site-packages\django\db\migrations\operations\fields.py",
line 62, in database_forwards
field, File "C:\Users\User\Anaconda3\lib\site-packages\django\db\backends\sqlite3\schema.py",
line 179, in add_field
self._remake_table(model, create_fields=[field]) File "C:\Users\User\Anaconda3\lib\site-packages\django\db\backends\sqlite3\schema.py",
line 147, in _remake_table
self.quote_name(model._meta.db_table), File "C:\Users\User\Anaconda3\lib\site-packages\django\db\backends\base\schema.py",
line 111, in execute
cursor.execute(sql, params) File "C:\Users\User\Anaconda3\lib\site-packages\django\db\backends\utils.py",
line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params) File "C:\Users\User\Anaconda3\lib\site-packages\django\db\backends\utils.py",
line 64, in execute
return self.cursor.execute(sql, params) File "C:\Users\User\Anaconda3\lib\site-packages\django\db\utils.py", line
98, in exit
six.reraise(dj_exc_type, dj_exc_value, traceback) File "C:\Users\User\Anaconda3\lib\site-packages\django\utils\six.py", line
685, in reraise
raise value.with_traceback(tb) File "C:\Users\User\Anaconda3\lib\site-packages\django\db\backends\utils.py",
line 64, in execute
return self.cursor.execute(sql, params) File "C:\Users\User\Anaconda3\lib\site-packages\django\db\backends\sqlite3\base.py",
line 318, in execute
return Database.Cursor.execute(self, query, params) django.db.utils.IntegrityError: NOT NULL constraint failed:
mainsite_weather__new.observe_time
I don't know what caused this error.
thx.

In order for this to work you should also make this field nullable and blankable, like this:
observe_time = models.DateTimeField(default=None, blank=True, null=True)
or omit default=None completely, like this:
observe_time = models.DateTimeField(blank=True, null=True)
Also, after that, don't forget to delete the previous migration file and run makemigrations and migrate again.

Updating the models in django

Initially my model looked something like this:
from __future__ import unicode_literals
from django.template.defaultfilters import slugify
from django.contrib.auth.models import User
from django.db import models
from datetime import datetime
class blogpost(models.Model):
title = models.CharField(max_length = 200)
body = models.TextField()
createdon = models.DateTimeField(auto_now_add=True)
slug = models.SlugField(unique=True)
author = models.ForeignKey(User)
I applied makemigrations and then migrate to this model. Now, I wanted to remove the field slug from this model. I removed it and then applied makemigrations.
^C(mysite)shivam#shivam-HP-Pavilion-15-Notebook-PC:~/Python/django/mysite/mysite$ python manage.py makemigrations
Migrations for 'blog':
0003_remove_blogpost_slug.py:
- Remove field slug from blogpost
But now when I apply migrate, it gives me an error.
Operations to perform:
Apply all migrations: admin, blog, contenttypes, auth, sessions
Running migrations:
Rendering model states... DONE
Applying blog.0003_remove_blogpost_slug...Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 350, in execute_from_command_line
utility.execute()
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 342, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/core/management/base.py", line 348, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/core/management/base.py", line 399, in execute
output = self.handle(*args, **options)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 200, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 92, in migrate
self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 121, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 198, in apply_migration
state = migration.apply(state, schema_editor)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/migrations/migration.py", line 123, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/migrations/operations/fields.py", line 121, in database_forwards
schema_editor.remove_field(from_model, from_model._meta.get_field(self.name))
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 438, in remove_field
self.execute(sql)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 110, in execute
cursor.execute(sql, params)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/utils.py", line 95, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 112, in execute
return self.cursor.execute(query, args)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/MySQLdb/cursors.py", line 205, in execute
self.errorhandler(self, exc, value)
File "/home/shivam/Python/django/mysite/local/lib/python2.7/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
raise errorclass, errorvalue
django.db.utils.OperationalError: (1091, "Can't DROP 'slug'; check that column/key exists")
What should I do to remove the slug field?