Does makemigrations in django recreates existing tables for a reason? - django

Question

I wanted to validate if there is a bug in makemigrations in django 1.8 with sql lite or I am doing something wrong.
After I Dropped my DB and deleted all migration folders. I run
python manage.py makemigrations
python manage.py migrate
DB gets created no problems.
2.I have to modify existing model in one of the apps (app abc)
I perform my change and run again
python manage.py makemigrations
3.it doesn't find any changes
then I run same thing again but with app name
python manage.py makemigrations abc
4.It does some updates in migrations , I believe it recreates all the tables and not just my change !!!!
5.Then I execute
python manage.py migrate
and getting error that table already exists .
Is it a bug in django framework or I am doing something wrong and there is a reason why it behaves this way?
Copy paste from my shell starting from step 2:
(mrp) C:\Users\I812624\dev\mrp\src>python manage.py makemigrations
No changes detected
(mrp) C:\Users\I812624\dev\mrp\src>python manage.py makemigrations purchase
Migrations for 'purchase':
0001_initial.py:
- Create model PO
- Create model POmaterial
(mrp) C:\Users\I812624\dev\mrp\src>python manage.py migrate
Operations to perform:
Synchronize unmigrated apps: customer, manufacture, product, django_filters, a
utofixture, staticfiles, messages, smart_selects, watson, sales, item, django_co
untries, mptt, inventory, django_select2, production, main, crispy_forms
Apply all migrations: purchase, vendor, sessions, admin, sites, flatpages, con
tenttypes, auth, registration
Synchronizing apps without migrations:
Creating tables...
Running deferred SQL...
Installing custom SQL...
Running migrations:
Rendering model states... DONE
Applying purchase.0001_initial...Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\core\management\__init
__.py", line 338, in execute_from_command_line
utility.execute()
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\core\management\__init
__.py", line 330, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\core\management\base.p
y", line 390, in run_from_argv
self.execute(*args, **cmd_options)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\core\management\base.p
y", line 441, in execute
output = self.handle(*args, **options)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\core\management\comman
ds\migrate.py", line 221, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\migrations\executor
.py", line 110, in migrate
self.apply_migration(states[migration], migration, fake=fake, fake_initial=f
ake_initial)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\migrations\executor
.py", line 147, in apply_migration
state = migration.apply(state, schema_editor)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\migrations\migratio
n.py", line 115, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, projec
t_state)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\migrations\operatio
ns\models.py", line 59, in database_forwards
schema_editor.create_model(model)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\backends\base\schem
a.py", line 282, in create_model
self.execute(sql, params or None)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\backends\base\schem
a.py", line 107, in execute
cursor.execute(sql, params)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\backends\utils.py",
line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\backends\utils.py",
line 64, in execute
return self.cursor.execute(sql, params)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\utils.py", line 97,
in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\backends\utils.py",
line 62, in execute
return self.cursor.execute(sql)
File "C:\Users\I812624\dev\mrp\lib\site-packages\django\db\backends\sqlite3\ba
se.py", line 316, in execute
return Database.Cursor.execute(self, query)
django.db.utils.OperationalError: table "purchase_po" already exists

Answer 1

To answer my own question .
So what I have figured out . I believe the problem is that I have originally deleted the folders migrations and when I run makemigrations without specifying particular app it does create a DB but it dosent create the folder makemigrations with ____init____.py inside it.
solution each time when you drop db and delete migrations folder for whatever reason dont just delete the migrations folder but only its content excluding init file.
Or when you do delete the folder run make migrations individually for each app as #MicroPyramid suggested.
Without doing deeper investigation it looks to me or as confusing designed behaviour or a bug from Django side.