A Guide on Django Models

Django models

Django models are the heart of the Django framework. They are used to define the structure of the database and the relationships between different models. In this section, we will explore the basics of Django models and how to create them.

Defining a model

So far, we have created a same chai app and it’s time to add some data to it. To do this, we need to define a model. A model is a Python class that represents a table in the database. It contains fields that define the structure of the table and methods that define the behavior of the table.

To define a model, we need to use the models.py file in our Django project. Add the following code to the models.py file:

from django.db import models
from django.utils import timezone

# Create your models here.

class ChaiVariety(models.Model):
  CHAI_TYPE_CHOICES = [
    ('ML', 'MASALA'),
    ('GR', 'GINGER'),
    ('KL', 'KIWI'),
    ('PL', 'PLAIN'),
    ('EL', 'ELAICHI'),
  ]

  name = models.CharField(max_length=100)
  image = models.ImageField(upload_to='chais/')
  date_added = models.DateTimeField(default=timezone.now)
  type = models.CharField(max_length=2, choices=CHAI_TYPE_CHOICES, default='ML')

  def __str__(self):
    return self.name

In this code, we have defined a ChaiVariety model with the following fields:

name: A CharField that stores the name of the chai variety.
image: An ImageField that stores the image of the chai variety.
date_added: A DateTimeField that stores the date and time when the chai variety was added.
type: A CharField that stores the type of the chai variety (e.g., ‘ML’, ‘GR’, ‘KL’, ‘PL’, ‘EL’).
description: A TextField that stores the description of the chai variety.

The __str__ method is used to return a string representation of the object. In this case, it returns the name of the chai variety.

Since we are using image field, we need to install Pillow library to use it.

python -m pip install Pillow

Then we need add some settings to our settings.py file to use the image field.

MEDIA_URL = '/media/'
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

Now, let’s configure our projects urls.py file to reflect media files.

from django.conf import settings
from django.conf.urls.static import static

urlpatterns = [
    path('admin/', admin.site.urls),
    #...
    #...
] + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

Adding data to the database

Now that we have defined our model, we can add some data to the database. Lets migrate the database and add some data to the ChaiVariety model.

python manage.py makemigrations chai
python manage.py migrate

Now, let’s add some data to the database. You can go to admin.py file and add the following code to the ChaiVariety model.

from django.contrib import admin
from .models import ChaiVariety

admin.site.register(ChaiVariety)

Now, go to the admin page and you should see the ChaiVariety model listed. Add some data to the model and save it.

Creating a view to display the data

Now that we have added some data to the database, we can create a view to display the data. Go to the views.py file and add the following code.

def all_chai(request):
  chais = ChaiVariety.objects.all()
  return render(request, 'chai/all_chai.html', {'chais': chais})

Get data in the template

In the all_chai.html template, we can use the chais variable to display the data. Add the following code to the all_chai.html template.

{% for chai in chais %}
  <div class="chai-item">
    <img src="{{ chai.image.url }}" alt="{{ chai.name }}">
    <h3>{{ chai.name }}</h3>
    <p>{{ chai.description }}</p>
  </div>
{% endfor %}

adding description to the model and details page

We can add a description to the ChaiVariety model by adding a description field to the model. Add the following code to the models.py file.

class ChaiVariety(models.Model):
  CHAI_TYPE_CHOICES = [
    ('ML', 'MASALA'),
    ('GR', 'GINGER'),
    ('KL', 'KIWI'),
    ('PL', 'PLAIN'),
    ('EL', 'ELAICHI'),
  ]

  name = models.CharField(max_length=100)
  image = models.ImageField(upload_to='chais/')
  date_added = models.DateTimeField(default=timezone.now)
  type = models.CharField(max_length=2, choices=CHAI_TYPE_CHOICES, default='ML')
  description = models.TextField(default='')

  def __str__(self):
    return self.name

Adding a details view

Now that we have added a description to the ChaiVariety model, we can create a view to display the details of a specific chai variety. Go to the views.py file and add the following code.

from django.shortcuts import render, get_object_or_404

def chai_detail(request, chai_id):
  chai = get_object_or_404(ChaiVariety, pk=chai_id)
  return render(request, 'chai/chai_detail.html', {'chai': chai})

In the all_chai.html template, we can use the url to display the details of a specific chai variety.

{% for chai in chais %}
  <div class="chai-item">
    <img src="{{ chai.image.url }}" alt="{{ chai.name }}">
    <h3>{{ chai.name }}</h3>
    <p>{{ chai.description }}</p>
    <a href="{% url 'chai_detail' chai.id %}">Details</a>
  </div>

{% endfor %}

Configuring the urls.py file

Now that we have created a view to display the details of a specific chai variety, we need to configure the urls.py file to reflect this. Go to the urls.py file and add the following code.

from django.urls import path
from . import views

urlpatterns = [
    path('', views.all_chai, name='all_chai'),
    path('<int:chai_id>/', views.chai_detail, name='chai_detail'),

]

Create `chai_detail.html` template

Now that we have created a view to display the details of a specific chai variety, we need to create a template to display the details. Go to the chai folder and create a new file called chai_detail.html. Add the following code to the chai_detail.html template.

<h1>{{ chai.name }}</h1>
<p>{{ chai.description }}</p>
<img src="{{ chai.image.url }}" alt="{{ chai.name }}">

Conclusion

In this section, we have learned how to create a model, add data to the database, create a view to display the data, and create a view to display the details of a specific chai variety. We have also learned how to configure the urls.py file to reflect the views and how to create a template to display the details. With these concepts, we can create a complete web application that allows users to add and view chai varieties.

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