DjangoのテストクライアントにおけるJSONレスポンスの解析: 従来の方法と test.Response.json() の比較

What is test.Response.json()?

test.Response.json() is a method added to the Response object in Django's test client in Django 4.2. It simplifies the process of parsing JSON responses from Django views in unit tests.

How does it work?

When you make a request to a Django view using the test client, the response object contains the JSON data that the view returned. The test.Response.json() method automatically parses this JSON data into a Python dictionary, making it easier to test and verify the response.

Why use it?

Before test.Response.json(), you had to manually parse the JSON data from the response object using the json module. This was more cumbersome and error-prone. test.Response.json() makes the process more streamlined and less error-prone.

How to use it?

To use test.Response.json(), simply call the method on the response object. For example:

response = self.client.get('/my-view/')
data = response.json()

self.assertEqual(data['status'], 'success')
self.assertEqual(data['data']['id'], 123)

In this example, data will be a Python dictionary containing the JSON data from the response. You can then use the dictionary to test and verify the response.

Here's an example of how to use test.Response.json() to test a view that returns a list of products:

class ProductListViewTest(TestCase):

    def test_product_list_view(self):
        response = self.client.get('/products/')
        products = response.json()

        self.assertEqual(response.status_code, 200)
        self.assertEqual(len(products), 3)

        for product in products:
            self.assertIn('id', product)
            self.assertIn('name', product)
            self.assertIn('price', product)

Additional notes:

• The test.Response.json() method also supports the headers parameter, which allows you to specify the headers to be included when parsing the JSON data.
• If the response is not JSON, the test.Response.json() method will raise a JSONDecodeError exception.

I hope this explanation is clear and helpful. Please let me know if you have any other questions.

Testing a view that returns a single product:

class ProductDetailViewTest(TestCase):

    def test_product_detail_view(self):
        product = Product.objects.create(name='My Product', price=9.99)
        response = self.client.get(f'/products/{product.id}/')
        product_data = response.json()

        self.assertEqual(response.status_code, 200)
        self.assertEqual(product_data['id'], product.id)
        self.assertEqual(product_data['name'], product.name)
        self.assertEqual(product_data['price'], product.price)

Testing a view that creates a new product:

class ProductCreateViewTest(TestCase):

    def test_product_create_view(self):
        data = {
            'name': 'My New Product',
            'price': 19.99,
        }
        response = self.client.post('/products/', data=data)
        self.assertEqual(response.status_code, 201)

        product = Product.objects.get(id=response.json()['id'])
        self.assertEqual(product.name, data['name'])
        self.assertEqual(product.price, data['price'])

Testing a view that updates an existing product:

class ProductUpdateViewTest(TestCase):

    def test_product_update_view(self):
        product = Product.objects.create(name='My Product', price=9.99)
        data = {
            'name': 'My Updated Product',
            'price': 14.99,
        }
        response = self.client.put(f'/products/{product.id}/', data=data)
        self.assertEqual(response.status_code, 200)

        product.refresh_from_db()
        self.assertEqual(product.name, data['name'])
        self.assertEqual(product.price, data['price'])

Testing a view that deletes a product:

class ProductDeleteViewTest(TestCase):

    def test_product_delete_view(self):
        product = Product.objects.create(name='My Product', price=9.99)
        response = self.client.delete(f'/products/{product.id}/')
        self.assertEqual(response.status_code, 204)

        self.assertFalse(Product.objects.filter(id=product.id).exists())

These are just a few examples of how to use test.Response.json() to test Django views that return JSON data. The possibilities are endless!

I hope these additional samples are helpful. Please let me know if you have any other questions.

Using the json module:

The traditional approach before test.Response.json() was to manually parse the JSON data from the response object using the json module. This involves the following steps:

1. Import the json module:

import json

1. Decode the JSON data from the response object:

json_data = json.loads(response.content)

1. Access the data using dictionary-like syntax:

data = json_data['key1']
data = json_data['key2']['nested_key']

Example:

def test_product_list_view(self):
    response = self.client.get('/products/')
    json_data = json.loads(response.content)

    self.assertEqual(response.status_code, 200)
    self.assertEqual(len(json_data['products']), 3)

    for product in json_data['products']:
        self.assertIn('id', product)
        self.assertIn('name', product)
        self.assertIn('price', product)

Using a third-party library:

There are several third-party libraries available for parsing JSON data in Python, such as simplejson and ujson. These libraries may offer performance advantages or additional features compared to the built-in json module.

Example using simplejson:

import simplejson

def test_product_list_view(self):
    response = self.client.get('/products/')
    data = simplejson.loads(response.content)

    self.assertEqual(response.status_code, 200)
    self.assertEqual(len(data['products']), 3)

    for product in data['products']:
        self.assertIn('id', product)
        self.assertIn('name', product)
        self.assertIn('price', product)

Considerations:

• Simplicity: test.Response.json() offers the simplest and most straightforward approach, as it directly integrates with the test client and simplifies the process.

• Performance: If you're dealing with large volumes of JSON data, consider using a high-performance JSON parsing library like ujson.

• Third-party dependencies: Using a third-party library introduces an additional dependency to your project.

Ultimately, the best choice depends on your specific needs and preferences. If simplicity and ease of use are your priorities, test.Response.json() is an excellent choice. For performance-critical scenarios or if you have specific requirements for JSON parsing, consider using a third-party library.

I hope this helps!