7. Details

Now we will take care of viewing the details of a specific book (GET).

We create the tests so we can check whether it returns the data of a specific book, and another one to check that it returns an error if it does not exist. We add both tests to tests/libros/test_views.py.

# tests/libros/test_views.py

import pytest
from app.libros.models import Libros

@pytest.mark.django_db
def test_add_book(client):

    # Given
    libros = Libros.objects.all()
    assert len(libros) == 0

    # When
    resp = client.post(
        "/api/libros/",
        {
            "title": "El fin de la eternidad",
            "genre": "Ciencia Ficción",
            "author": "Isaac Asimov",
            "year": "1955",
        },
        content_type="application/json"
    )

    # Then
    assert resp.status_code == 201
    assert resp.data["title"] == "El fin de la eternidad"

    libros = Libros.objects.all()
    assert len(libros) == 1

@pytest.mark.django_db
def test_get_single_book(client): # new

    # Given
    libro = Libros.objects.create(
        title="El fin de la eternidad",
        genre="Ciencia Ficción",
        author="Isaac Asimov",
        year="1955",
        )

    # When
    resp = client.get(f"/api/libros/{libro.id}/")

    # Then
    assert resp.status_code == 200
    assert resp.data["title"] == "El fin de la eternidad"

@pytest.mark.django_db
def test_get_single_libro_incorrect_id(client): # new

    # When
    resp = client.get(f"/api/libros/-1/")

    # Then
    assert resp.status_code == 404

It is time to define the view.

# app/libros/views.py

from django.http import JsonResponse
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from .serializers import LibroSerializer
from .models import Libros

def ping(request):
    data = {"ping": "pong!"}
    return JsonResponse(data)

class LibrosList(APIView):

    def post(self, request):
        serializer = LibroSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

class LibrosDetails(APIView): # new

    def get(self, request, pk):
        libro = Libros.objects.filter(pk=pk).first()
        serializer = LibroSerializer(libro)
        if libro:
            return Response(serializer.data, status=status.HTTP_200_OK)
        return Response(serializer.errors, status=status.HTTP_404_NOT_FOUND)

And register its url. We tell it that it will need a number after libros. For example api/libros/23/.

# app/libros/urls.py

from django.urls import path
from app.libros.views import *

urlpatterns = [
    path("ping/", ping, name="ping"),
    path("api/libros/", LibrosList.as_view()),
    path("api/libros/<int:pk>/", LibrosDetails.as_view()), # new
]

The test will now pass.

You can also check with an HTTP client what you receive. (Don't forget to start the server and create a book)

# curl
curl http://localhost:8000/api/libros/1/

# HTTPie
http GET http://localhost:8000/api/libros/1/

Allow: GET, HEAD, OPTIONS
Content-Length: 192
Content-Type: application/json
Date: Mon, 12 Jul 2021 21:00:51 GMT
Referrer-Policy: same-origin
Server: WSGIServer/0.2 CPython/3.9.2
Vary: Accept, Cookie
X-Content-Type-Options: nosniff
X-Frame-Options: DENY

{
    "author": "Isaac Asimov",
    "created_at": "2021-07-11T21:30:04.088124Z",
    "genre": "Ciencia Ficción",
    "id": 1,
    "title": "El fin de la eternidad",
    "updated_at": "2021-07-11T21:30:04.088160Z",
    "year": "1955"
}