OperationalError at /admin/learning_logs/example/

Question

I am a beginner at the django and module and web applications.

Here is the traceback and the data:

OperationalError at /admin/learning_logs/example/
no such column: learning_logs_example.entry_id
Request Method: GET
Request URL:    http://localhost:8000/admin/learning_logs/example/
Django Version: 1.11.7
Exception Type: OperationalError
Exception Value:    
no such column: learning_logs_example.entry_id
Exception Location: C:\Users\Bryan\Desktop\LEARNI~1\ll_env\lib\site-
packages\django\db\backends\sqlite3\base.py in execute, line 328
Python Executable:  C:\Users\Bryan\Desktop\LEARNI~1\ll_env\Scripts\python.exe
Python Version: 3.6.2
Python Path:    
['C:\\Users\\Bryan\\Desktop\\learning log',
 'C:\\Users\\Bryan\\Desktop\\LEARNI~1\\ll_env\\Scripts\\python36.zip',
 'C:\\Users\\Bryan\\AppData\\Local\\Programs\\Python\\Python36-32\\DLLs',
 'C:\\Users\\Bryan\\AppData\\Local\\Programs\\Python\\Python36-32\\lib',
 'C:\\Users\\Bryan\\AppData\\Local\\Programs\\Python\\Python36-32',
 'C:\\Users\\Bryan\\Desktop\\LEARNI~1\\ll_env',
 'C:\\Users\\Bryan\\Desktop\\LEARNI~1\\ll_env\\lib\\site-packages']
Server time:    Sat, 18 Nov 2017 18:36:14 +0000

For some reason, when I click that link that says "Examples" below,

it says this

I tried migrating but it says

(venv) C:\...\learning log>python manage.py makemigrations
No changes detected

(venv) C:\...\learning log>python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  No migrations to apply.

How did I get it to do that?

Well first I added the example entry/form with a TextField and then I added a "example". I added a ForeignKey object with the parameter as Entry.

I went back to edit my "example" but then the exception showed up.

EDIT: Well janos wanted the output when I run python manage.py showmigrations learning_logs so here it is:

admin
 [X] 0001_initial
 [X] 0002_logentry_remove_auto_add
auth
 [X] 001_initial
 [X] 0001_initial
 [X] 0002_alter_permission_name_max_length
 [X] 0003_alter_user_email_max_length
 [X] 0004_alter_user_username_opts
 [X] 0005_alter_user_last_login_null
 [X] 0006_require_contenttypes_0002
 [X] 0007_alter_validators_add_error_messages
 [X] 0008_alter_user_username_max_length
contenttypes
 [X] 0001_initial
 [X] 0002_remove_content_type_name
learning_logs
 [X] 0001_initial
sessions
 [X] 0001_initial

Well I hope that helped.

I recreated the exception page right here

Answer 1

If data isn't matter, you can just drop your database file from here:

C:\Users\bryan_8nva8ki\Desktop\learning logs\db.sqlite3

(I saw that path from your logs)

Then you should make migrate again. Hope it will helps!

Answer 2

As the error message says, the column entry_id in the table learning_logs_example does not exist. This is not normal. If schema migrations were created correctly and applied correctly, then this should not happen.

Moreover, looking at this:

(venv) C:\...\learning log>python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  No migrations to apply.

The Apply all migrations line should contain the name of your app. The existing names are standard Django components. The name of your app is probably learning_log or similar. In short, it seems that migrations don't exist for your app.

To debug this, first of all check the output of showmigrations for your app:

./manage.py showmigrations learning_log

If you don't get an error, then please add the output to your question.

If you get an error CommandError: No migrations present for: ..., then create the migrations:

./manage.py makemigrations learning_log

And then check the output of showmigrations again, and please add the output to your question.

If the output looks something like this:

learning_log
 [X] 0001_initial
 ...

That means the database has some records about applied migrations, and in fact Django thinks that the migrations are correctly applied. (When in fact they are not, based on your main error.)

With the information I have so far, it seems your database got out of sync with the model: some fields have been added to the model without applying to the database, and the migrations were not correctly saved.

One simple solution could be to manually add the missing columns. You can find the correct schema by looking at the migration file:

./manage.py sqlmigrate learning_log 0001

From this you should be able to find how the missing entry_id field is declared, and then manually add it to the table with a query ALTER TABLE learning_logs_example ADD COLUMN entry_id ..., where the rest of the parameters depend on the definition of the column in the output of sqlmigrate.

If the problem is only one or a few missing fields, then this workaround may be enough to have something working. (If not, then jump to the next section.) You should not stop there though, because the model may need some indexes as well. You could either study further output of sqlmigrate and recreate all other objects that depend on learning_logs_example, such as indexes, triggers. But a cleaner solution will be to recreate all the tables of the app, following these steps:

• Dump the current data: ./manage.py dumpdata learning_log > learning_log.json
• Drop all tables of the app
• Recreate the tables of the app: ./manage.py migrate --fake learning_log zero; ./manage.py migrate learning_log
• Restore the data: ./manage.py loaddata learning_log

---

If the workaround of adding columns manually doesn't work (you stumble into more complicated problems), then you have two choices:

• If you cannot afford to lose data, well then you will have to track down and solve every single problem manually. After that's done, you should dump and restore the tables of the app as I explained in the previous section

• If it's ok to lose data, then you can follow the procedure in the previous section, without the dumping and restoring steps. That is, drop and recreate the tables of the app

---

Finally, to avoid further problems, you need to make sure that all migrations are in sync with the model, and are correctly added to version control. A good way to test that is install the Django project in a different folder on your computer. If that doesn't go smoothly, then the setup is still not good.

---

Let me know if any of the above needs more clarification.

Answer 3

Is this the first time you are creating migrations for your application? If so, you need to specify the app name to make the migrations:

python manage.py makemigrations my-app