Adding a field to a model after initial migration

[ofeyofey]

Hi,
I forgot to add a field to a model and wish to add it now.
I added the line to models.py but makemigrations and migrate aren't working now.
Is this possible in Django or do i need to go directly tp the sqlite DB and do it using SQL?
Thanks
Currently following this tutorial https://www.youtube.com/watch?v=g0tvJsUAx7g

[sum abiut]

What error did your get? what command did you use?

try

python manage.py makemigrations

python manage.py migrate

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[Xristos Xristoou]

no the problem is your new field affect models rules...try the new field to have null=True or default=somathing and then run on mynage.py makemigration yourapp and after migrate yourapp

christos

[ofeyofey]

Thanks for your reply.

The model.py contains,

class SignUp(models.Model):
    email = models.EmailField()
    full_name =  models.CharField(max_length = 120, blank = True, null = True)
    timestamp = models.DateTimeField(auto_now_add = True, auto_now = False)
    updated = models.DateTimeField(auto_now_add = False, auto_now = True)

    def __unicode__(self): #__str__ for python3

          return self.email

I had to add the updated field,

updated = models.DateTimeField(auto_now_add = False, auto_now = True)

Running make migrations,

[pi@Huawei-HG658c-instalacion src]$ python manage.py makemigrations
/home/pi/src/djangoTest/urls.py:20: RemovedInDjango110Warning: Support for string view arguments to url() is deprecated and will be removed in Django 1.10 (got news.views.home). Pass the callable instead.
  url(r'^$', 'news.views.home', name='home'),

No changes detected

Then running migrations

[pi@Huawei-HG658c-instalacion src]$ python manage.py migrate
/home/pi/src/djangoTest/urls.py:20: RemovedInDjango110Warning: Support for string view arguments to url() is deprecated and will be removed in Django 1.10 (got news.views.home). Pass the callable instead.
  url(r'^$', 'news.views.home', name='home'),

Operations to perform:
  Apply all migrations: admin, news, contenttypes, auth, sessions
Running migrations:
  Rendering model states... DONE
  Applying news.0002_signup_updated...Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/lib/python2.7/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
    utility.execute()
  File "/usr/lib/python2.7/site-packages/django/core/management/__init__.py", line 345, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 348, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/usr/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 "/usr/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 "/usr/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 "/usr/lib/python2.7/site-packages/django/db/migrations/executor.py", line 198, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/usr/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 "/usr/lib/python2.7/site-packages/django/db/migrations/operations/fields.py", line 62, in database_forwards
    field,
  File "/usr/lib/python2.7/site-packages/django/db/backends/sqlite3/schema.py", line 221, in add_field
    self._remake_table(model, create_fields=[field])
  File "/usr/lib/python2.7/site-packages/django/db/backends/sqlite3/schema.py", line 103, in _remake_table
    self.effective_default(field)
  File "/usr/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 210, in effective_default
    default = field.get_db_prep_save(default, self.connection)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 728, in get_db_prep_save
    prepared=False)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1461, in get_db_prep_value
    value = self.get_prep_value(value)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1440, in get_prep_value
    value = super(DateTimeField, self).get_prep_value(value)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1296, in get_prep_value
    return self.to_python(value)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1399, in to_python
    parsed = parse_datetime(value)
  File "/usr/lib/python2.7/site-packages/django/utils/dateparse.py", line 93, in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or buffer

Thanks,

[Xristos Xristoou]

work now ?

Τη Τετάρτη, 27 Ιανουαρίου 2016 - 9:21:16 μ.μ. UTC+2, ο χρήστης ofeyofey έγραψε:

[ofeyofey]

Hi,

I changed the line to

updated = models.DateTimeField(auto_now_add = False, auto_now = True, null=True)

But the same results,

[pi@Huawei-HG658c-instalacion src]$ python manage.py makemigrations
/home/pi/src/djangoTest/urls.py:20: RemovedInDjango110Warning: Support for string view arguments to url() is deprecated and will be removed in Django 1.10 (got news.views.home). Pass the callable instead.
  url(r'^$', 'news.views.home', name='home'),

Migrations for 'news':
  0003_auto_20160127_2109.py:
    - Alter field updated on signup

[pi@Huawei-HG658c-instalacion src]$ python manage.py migrate
/home/pi/src/djangoTest/urls.py:20: RemovedInDjango110Warning: Support for string view arguments to url() is deprecated and will be removed in Django 1.10 (got news.views.home). Pass the callable instead.
  url(r'^$', 'news.views.home', name='home'),

Operations to perform:
  Apply all migrations: admin, news, contenttypes, auth, sessions
Running migrations:
  Rendering model states... DONE
  Applying news.0002_signup_updated...Traceback (most recent call last):
  File "manage.py", line 10, in <module>

...........

  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1399, in to_python
    parsed = parse_datetime(value)
  File "/usr/lib/python2.7/site-packages/django/utils/dateparse.py", line 93, in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or buffer

Thanks

On Wednesday, 27 January 2016 19:21:16 UTC, ofeyofey wrote:

[Xristos Xristoou]

you add your app name after the run makemigration and migrate ?if your app name is a blog then you run makemigration blog and migrate blog

Τη Τετάρτη, 27 Ιανουαρίου 2016 - 9:21:16 μ.μ. UTC+2, ο χρήστης ofeyofey έγραψε:

[ofeyofey]

Ok I put the app name which is 'news' after the commands for makemigrations and for migrate.
But I am still getting the same results.

On Wednesday, 27 January 2016 19:21:16 UTC, ofeyofey wrote:

[Xristos Xristoou]

i dont know why sorry..try default value

Τη Τετάρτη, 27 Ιανουαρίου 2016 - 9:21:16 μ.μ. UTC+2, ο χρήστης ofeyofey έγραψε:

[ofeyofey]

No problem. Thanks for your help.
Maybe fields can't be added to a model with django.
I will try dropping the table in the DB and see what happens.
Thanks again,

On Wednesday, 27 January 2016 19:21:16 UTC, ofeyofey wrote:

[sum abiut]

You should try running it as root.

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[ofeyofey]

Alas too late... I have dropped the table.
But this link http://www.djangobook.com/en/2.0/chapter10.html
to a Django Book for version 1.0 may hold some ideas under the section about adding fields.
Thanks

On Wednesday, 27 January 2016 19:21:16 UTC, ofeyofey wrote:

[Daniel Roseman]

On Wednesday, 27 January 2016 21:29:18 UTC, ofeyofey wrote:

No problem. Thanks for your help.
Maybe fields can't be added to a model with django.
I will try dropping the table in the DB and see what happens.
Thanks again,

Adding fields to models is quite literally what migrations are for.

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DR. 

[Guan Ke]

When you run makemigrations command, Django will compare your current model module with the newest migration module. You should have a look at your 0002_signup_updated... file to find out what cause the problem.