Purpose – To use the Django Models as blueprints for creating the Database tables using the Django utilities

Pre-requisities –

Ubuntu 18.04

Python 3.5 and later

pip3 latest version

Django 2.1 and later

Procedure –

In this article we will see how we can use the Django Models to layout the Models Objects as tables in the Databases. By default in the Django Projects settings.py the default SQLLite Database is configured for usage. We can either use the default Database or we can configure the setting to point to a different Database if we wish to connect to a different Database for configuration.

user@c531f04d55ac:/projects$ python -m django –version

2.1.5

Here we have already created a project by name mysite as per the quickstart documents and went into the project folders as below where we can find the setting.py file which contains the project specfic settings.

user@c531f04d55ac:/projects/mysite/mysite$ grep -A 10  Database settings.py

# Database

# https://docs.djangoproject.com/en/2.1/ref/settings/#databases

DATABASES = {

    ‘default’: {

        ‘ENGINE’: ‘django.db.backends.sqlite3’,

        ‘NAME’: os.path.join(BASE_DIR, ‘db.sqlite3’),

    }

}

user@c531f04d55ac:/projects/mysite$ python manage.py startapp students

user@c531f04d55ac:/projects/mysite$ ls -ltr students/

total 20

-rw-r–r– 1 user user  0 Apr  1 20:59 __init__.py

-rw-r–r– 1 user user 63 Apr  1 20:59 admin.py

-rw-r–r– 1 user user 91 Apr  1 20:59 apps.py

-rw-r–r– 1 user user 60 Apr  1 20:59 tests.py

-rw-r–r– 1 user user 57 Apr  1 20:59 models.py

-rw-r–r– 1 user user 63 Apr  1 20:59 views.py

drwxr-xr-x 2 user user 25 Apr  1 20:59 migrations

user@c531f04d55ac:/projects/mysite/students$ cat models.py

from django.db import models

# Create your models here.

class Students(models.Model):

        full_name = models.CharField(max_length = 70)

class StudentInfo(models.Model):

        name = models.ForeignKey(Students, on_delete = models.CASCADE)

        gender = models.CharField(max_length = 10)

        standard = models.IntegerField(default = 0)

        division = models.CharField(max_length = 1)

As we have created a new Application name called students, we need to include that Application in the mysite project settings

user@c531f04d55ac:/projects/mysite/mysite$ grep -A 10 INSTALLED_APPS settings.py

INSTALLED_APPS = [

    ‘students.apps.StudentsConfig’,

    ‘polls.apps.PollsConfig’,

    ‘django.contrib.admin’,

    ‘django.contrib.auth’,

    ‘django.contrib.contenttypes’,

    ‘django.contrib.sessions’,

    ‘django.contrib.messages’,

    ‘django.contrib.staticfiles’,

Now that we have created our two models, we need to tell django to we have made some changes to the models for students Application and we would like to store those changes in the migration using the below command

user@c531f04d55ac:/projects/mysite$ python manage.py makemigrations students

Migrations for ‘students’:

  students/migrations/0001_initial.py

    – Create model StudentInfo

    – Create model Students

    – Add field name to studentinfo

Once, we created the migrations, we can validate the SQL queries that will be executed against the database to create the Database tables related to the Models that we just created above.

user@c531f04d55ac:/projects/mysite$ python manage.py sqlmigrate students 0001

BEGIN;

—

— Create model StudentInfo

—

CREATE TABLE “students_studentinfo” (“id” integer NOT NULL PRIMARY KEY AUTOINCREMENT, “gender” varchar(10) NOT NULL, “standard” integer NOT NULL, “division” varchar(1) NO

T NULL);

—

— Create model Students

—

CREATE TABLE “students_students” (“id” integer NOT NULL PRIMARY KEY AUTOINCREMENT, “full_name” varchar(70) NOT NULL);

—

— Add field name to studentinfo

—

ALTER TABLE “students_studentinfo” RENAME TO “students_studentinfo__old”;

CREATE TABLE “students_studentinfo” (“id” integer NOT NULL PRIMARY KEY AUTOINCREMENT, “gender” varchar(10) NOT NULL, “standard” integer NOT NULL, “division” varchar(1) NO

T NULL, “name_id” integer NOT NULL REFERENCES “students_students” (“id”) DEFERRABLE INITIALLY DEFERRED);

INSERT INTO “students_studentinfo” (“name_id”, “gender”, “division”, “standard”, “id”) SELECT NULL, “gender”, “division”, “standard”, “id” FROM “students_studentinfo__old

“;

DROP TABLE “students_studentinfo__old”;

CREATE INDEX “students_studentinfo_name_id_474a2cbf” ON “students_studentinfo” (“name_id”);

COMMIT;

user@c531f04d55ac:/projects/mysite$ python manage.py migrate

Operations to perform:

  Apply all migrations: admin, auth, contenttypes, polls, sessions, students

Running migrations:

  Applying students.0001_initial… OK

With the above step execute we have created empty tables related to Students and StudentInfo. Now we can use the Python shell to query our Database tables using the API

Hope you enjoyed reading this article. Thank you.