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django table has no column named Exception

Git Repository
Request to guide me on what to do.
I work on an e-commerce website with the help of Django. and I'm a beginner in Django
The following image provides a table of my database. It helps to add a product
Shows me an error in the browser. This error shows me when I add a product inside the admin panel. It helps to add a product but when I add the product the following error occurs.
An error occurred while migrating
Request to guide me on what to do.

After first migrations,if you add any field that can not be null you must provide a default value. Your desc field is not nullable, so you must add default='some_value' inside your desc field.

Do you have the table ready and set up? Because the error says, that there is a table named shop_product, but it does not have a column named product_name.
So the structure of your table would get us closer to the solution of your problem.
Edit:
I have just seen, that you supplied your Git repo. I looked at the database and what I wrote above holds true. Your shop_product table has no columns. I did not look through your code to see if it would be set up automatically, but I suppose you were supposed to create the columns by hand, right?

Take a look at here (Django Migrations Workflow)
I've seen your migrations folder on your Github repo and there was no sign of any of the fields you mentioned.
Every time you add fields to your models, you need to run following commands in terminal
python manage.py makemigrations <app name>
python manage.py migrate
These commands are going to modify your tables.
Please markdown your question instead of putting a picture from your code.
Check this out: How do I ask a good question?
EDIT:
In your Product model, there is a field named desc. You need to set a default value for it; Otherwise, you need to update the records in your database manually.
desc = models.CharField(max_length=300, default='')
After you do that, this error will happen to the pub_date field too. So, if your current Product objects in your database are not important, you can simply delete the database file db.sqlite3 and delete your migrations file from this address shop/migrations/0001_initial.py and try the migration commands again.

django asking to add default values

I am new to django and I am facing some problem.
This was my previous model.
class Blog(models.Model):
name = models.CharField(max_length=100)
tagline = models.TextField()
I added some data to this model.
After that I added one more field to it.
Now my model looks like this..
class Blog(models.Model):
name = models.CharField(max_length=100)
tagline = models.TextField()
age = models.IntegerField()
When I ran the command python manage.py makemigrations I got the following error which is obvious.
You are trying to add a non-nullable field 'age' to blog without a default; we can't do that (the database needs something to populate existing rows).
Please select a fix:
1) Provide a one-off default now (will be set on all existing rows with a null value for this column)
2) Quit, and let me add a default in models.py
Select an option:
I don't want to add default so I deleted the table contents by accessing db.sqlite3
But again after running python manage.py makemigrations I am getting the same error.why?

Even though you have deleted the table, any changes to your Django model will always refer to the previous migration of that model, hence it still requires you to set a default value. If you're still in development, then you could delete the migrations for that model and then makemigrations again. But, this is terrible practice and you should never do this unless you are consciously squashing your models, the better way is to do what Django is telling you and set a default. This'll help in the long run anyways with error handling.
The other answers address how to set defaults quite well.

When you add a new field (i.e., column) to a database table, that field applies to all rows in the table...the existing ones and any new ones. If the field cannot be null, then some value must be specified for all of the existing rows.
By default, IntegerField() is non-nullable. This explains why you are getting the warning. You have a few options:
You can choose a default "one-off" initial value like Django suggests. All existing rows will use this value for the new field.
Assign your own values to each existing row for the new field.
Use the blank and null arguments in your model field to allow the field to accept null values.
For the last option, you'd do this like so:
models.IntegerField(blank=True, null=True)
But that might not be the best choice depending on your use case. If nullable values don't make sense for your field, I would avoid making the field support nulls.

age = models.IntegerField(null=True)
Django models fields are null set to true by default.

The way you can solve this:
Delete the Blog table from the database.
Delete the migrations folder from the app that contains Blog model.
Remove all data from django_migrations table.
Now run makemigrations and then migrate command.
Hope this will solve your problem.

Do what Django is telling you, then you can remove the default attribute if you don't need it. But it's a good practice to keep it anyway

Django automatically create primary keys for existing database tables

I have an existing database that I'm trying to access with Django. I used python manage.py inspectdb to create the models for the database. Currently I'm able to import the models into the python shell however when I try to access any of the actual objects in any way, I get this error OperationalError: (1054, "Unknown column 'some_table.id' in 'field list'"). I see that the table in the database in fact does not have an id field. How can I fix this? Do I need to update the managed field in the Meta class and run a migration so it can create this field automatically?

From the Django documentation: This feature is meant as a shortcut, not as definitive model generation. See the documentation of inspectdb for more information. (Reference: https://docs.djangoproject.com/en/1.8/howto/legacy-databases/)
You're going to need to manually clean up the models and migrate. The line you'll have to add for adding the "id" field is:
id = models.IntegerField(primary_key=True)
Warning: I'd definitely create a copy of the database to toy with, rather than the original. This will likely take you some trial and error to get right. After you're absolutely sure you have it right, you can changed Managed=True, but be VERY careful!

Update Field schema in Django Model

I'm trying to update a field key from the following in the model:
name = models.CharField(max_length=255, unique = True)
to:
name = models.CharField(max_length=255, unique = False)
However I need to update the mysql db without losing any of the current data. How would I go about doing this? I tried $ python manage.py syncdb but it doesn't seem to update the key.

That is because syncdb doesn't do that. It only creates new tables, but doesn't change the existing if your model changes.
On a dev environment, to update your database after changing your model, you can use python manage.py reset appname to empty out your database, and use syncdb again.
Otherwise, you have to use tools such as South. South was made to handle migrations, but also changing the database when the model changes.
There is also django-evolutions that does just what you want, but I still recommend South as its migrations features are almost always going to be of some use.

You could use PHPMyAdmin and remove the unique index from this field.

"DatabaseError, column does not exist". But shows in my manage.py sql

Regarding Django & Python:
The Error:
Exception Type: DatabaseError
Exception Value:
column objects_thing.name_id does not exist
LINE 1: ...s_thing"."created", "objects_thing"."modified", "objects...
In my manage.py sql objects
CREATE TABLE "objects_thing" (
otherstuff,
otherstuff,
"name_id" integer NOT NULL REFERENCES "profiles_name" ("id"),
otherstuff,
);
So it clearly exists.
I've ran syncdb.
Why am I getting this error? And how do I go about fixing it? (I'm a newbie to all of this) Thank you in advance for the help.
EDIT:
Thing Model:
class Thing(models.Model):
created = models.DateTimeField(auto_now_add=True)
modified = models.DateTimeField(auto_now=True)
name = models.ForeignKey(Name)#The name for this thing
current_allocation = models.DecimalField(max_digits=13, decimal_places=2, null=True, blank=True)
target_allocation = models.DecimalField(max_digits=13, decimal_places=2, null=True, blank=True)
placeholder = models.ForeignKey(Entity, null=True, blank=True, on_delete=models.SET_NULL)
avatar = models.ImageField(upload_to='avatars/thing/', null=True, blank=True)

syncdb doesn't change existing tables in your database, so if you run that, and then change your model, your model is now out of sync with the table it represents. Running syncdb again will not fix that.
You either need to use something like south to do a migration, delete the table from your DB so that syncdb will recreate it, or manually run an ALTER TABLE on your DB.
EDIT (greater detail)
When you create a subclass of Model in models.py, it acts as a representation of a database table, but doesn't automatically have a database table. You get that by running python manage.py syncdb. Django, then, looks through all your models.py files, generates the SQL required to actually create a table like that and then runs it on your database. The end result is that you end up with actual database tables that are tied to your models.
However, syncdb only creates tables. It does not alter them. So, if you go and change one of your models (add a field, change the name of a field, etc.), nothing has happened at the database level. Running syncdb again will not help, either, because there's no new tables to create. You have to somehow get the table to match the model and vice versa, though, so that's where your options come in:
Use South (link above). South enables you to create migrations, so when you change something on your models you can run:
python manage.py schemamigration --auto yourapp
And it will generate code that will alter the table to match your model. You then need only apply the migration with:
python manage.py migrate yourapp
And you're done. The table now matches your model and all is right in the world again.
You can manually delete the table from your database. You wouldn't want to do this in production because all the data in that table will go along with it, but in development it shouldn't be a problem. After the table is gone, you can then run:
python manage.py syncdb
Because, the table no longer exists, Django will create it, but it will create it based on your current model's state. The net result is the same, your model and table match, so you're good to go.
You can manually alter the table. This requires that you figure out what SQL needs to be applied to change the table to match your model. You run this SQL on your database, and then the table is in parity with the model.
The point is that somehow, someway, you must update the table to reflect any changes you make to your models. The model isn't the table, it's just a programmatic representation of it.

The column might not necesarrily exist. The sql command just shows the sql used to create it, It is based on your current model. You could delete the table and re syncdb or manually add the column. https://docs.djangoproject.com/en/dev/ref/django-admin/#sql-appname-appname
I think there is a little confusion regarding the django Model and the actual database table
The django model is just some python code. It is a python object that is connected to a sql table. The database backend is specified in settings.py. The database contains the actual table. The error you are encountering is indicating that the python model is not the same as the actual database table.