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I'm trying to add an external key to the model Article.New column: author.

   title=models.CharField(max_length=30);
    description=models.TextField();
    date=models.DateTimeField(auto_now_add=True);
    author=models.ForeignKey(User,default=None,on_delete=models.PROTECT)

Byt after migrate I got are error:

OperationalError at /articles/ no such column: articles_article.author_id

Article list:

def article_list(requwest):
    articles=Article.objects.all().order_by('date')
    return render(requwest,"articles/article_list.html",{'articles':articles})

template:

<div class="articles">
        {% for article in articles %}
            <div class="article">

                <p>{{article.snipped}}</p>
                 <p>{{article.date}} </p>
            </div>
        {% endfor %}
    </div>

I use this lesson:lesson

After update models to:
author = models.ForeignKey(User, blank=True, on_delete=models.PROTECT)

django.db.utils.OperationalError: no such column: articles_article.author_id

python manage.py makemigrations
python manage.py migrate

Add a new field to an ASP.NET Core MVC app, Learn how to use Entity Framework Code First Migrations to add a new field to a model and migrate that change to a database. add-migration AddRatingMig The add-migration command tells the migration framework to examine the current movie model with the current movie DB schema and create the necessary code to migrate the DB to the new model. The AddRatingMig is arbitrary and is used to name the migration file. It's helpful to use a meaningful name for the migration step.

author=models.ForeignKey(User,blank=True,on_delete=models.PROTECT)

and then run migrations.

Adding a New Field to the Movie Model and Table, Note: An updated version of this tutorial is available here that uses ASP.NET MVC 5 and Visual Studio 2013. It's more secure, much simpler to  When the application starts, it detects that the model structure no longer matches the database schema. It automatically re-creates the database to match the new model structure and populates the database with the sample movies: Click the Create New link to add a new movie. Note that you can add a rating. Click Create. The new movie, including the rating, now shows up in the movies listing:

From the doc

Migrations are Django’s way of propagating changes you make to your models (adding a field, deleting a model, etc.) into your database schema.

The error raised because you haven't migrated the database with new changes (ie, the author field) First you have to add null=True to models as

author=models.ForeignKey(User,default=None,null=True,on_delete=models.PROTECT)

then, open your terminal and run the command one by one 1. python manage.py makemigrations 2. python manage.py migrate Here you can find a nice article about Django's Migrations, Django Migrations: A Primer

How To Add New Model Field To Exist Django Model, Change model class field in Django application models.py file. Below example add a new field user_desc = models.CharField(max_length=100,  To answer your question, with the new migration introduced in Django 1.7, in order to add a new field to a model you can simply add that field to your model and initialize migrations with./manage.py makemigrations and then run./manage.py migrate and the new field will be added to your DB.

Answer:

1)model:

   author = models.ForeignKey(User, null=True, blank=True, on_delete=models.PROTECT)

2) Dell db.sqlite3
3) python manage.py makemigrations
4) python manage.py migrate

Problem adding new fields to model : django, I had a model (let's call it Item or something), and data associated with that model​. I added a new field prev_amount to the model: prev_amount = models. Adds a new field to a table or the table of a feature class, feature layer, and/or rasters with attribute tables. Usage For shapefiles and dBase tables, if field type defines a character, blanks are inserted for each record.

Steps to Add New Field With Code First Approach in .NET Core , Let us first add a new field to the Employee model. We will add EmployeeLocation as shown below: Note: Please note that EmployeeLocation is​  In the above example last 2 fields false, true specifies the upsert and multi flags. Upsert: If set to true, creates a new document when no document matches the query criteria. Multi: If set to true, updates multiple documents that meet the query criteria. If set to false, updates one document.

Writing custom model fields | Django documentation, If you haven't added any extra options on top of the field you inherited from, then there's no need to write a new deconstruct() method. If, however, you're changing​  Add a custom attribute to a Laravel / Eloquent model on load? 'available' is not a field in the underlying table. That can be used automatically to add new

Models | Django documentation, Each attribute of the model represents a database field. When you add new apps to INSTALLED_APPS , be sure to run manage.py migrate , optionally making  I encountered the same problem and finally found out how to add a new column in the existing data model: Click 'Edit Queries' > Manage > Add items then select the fields you want to add and click OK. Message 10 of 10

Comments
  • django.db.utils.IntegrityError: NOT NULL constraint failed: articles_article.author_id
  • Could you add some comments on what this does and why it solves the problem?
  • "django.db.utils.IntegrityError: NOT NULL constraint failed: articles_article.author_id"
  • Could you add some comments on what this does and why it solves the problem?
  • delete the migration folder and try again.
  • Error: django.db.utils.IntegrityError: NOT NULL constraint failed: articles_article.author_id
  • @rand_triest When did you got this error? While running the command? or While inserting data into the DB ?
  • You should add null=True to your author field if you want to allow null values (which you’re defining as default).
  • @henriquesalvaro Thanx for the suggestion. I've updated it :)
  • "NOT NULL constraint failed: articles_article.author_id"