Utilizing correct Django CSRF validation when making a fetch post request

Question

Utilizing correct Django CSRF validation when making a fetch post request

I've been experimenting with JavaScript's fetch library to perform a form submission on my Django application. Despite my efforts, I keep running into CSRF validation issues.

The Ajax documentation suggests specifying a header, which I have attempted to implement.

I've also tried fetching the token using a templatetag and including it in the form data.

Unfortunately, neither method seems to resolve the problem.

Below is the sample code that includes both the form value and the header:

let data = new FormData();
data.append('file', file);
data.append('fileName', file.name);
// add form input from hidden input elsewhere on the page
data.append('csrfmiddlewaretoken', $('#csrf-helper input[name="csrfmiddlewaretoken"]').attr('value'));
let headers = new Headers();
// add header from cookie
const csrftoken = Cookies.get('csrftoken');
headers.append('X-CSRFToken', csrftoken);
fetch("/upload/", {
    method: 'POST',
    body: data,
    headers: headers,
})

While I have successfully achieved this using jQuery, I wanted to explore the possibility of utilizing fetch.

javascript django django-csrf fetch-api

Answer 1

Answer №1

Figured it out. The main issue here is that fetch does not automatically send cookies.

The solution is fairly simple - just add credentials: "same-origin" to your request and it should work fine (especially with the form data, albeit without the headers). Here is the revised and working code:

let formData = new FormData();
formData.append('file', file);;
formData.append('fileName', file.name);
// include form input from a hidden field elsewhere in the document
formData.append('csrfmiddlewaretoken', $('#csrf-helper input[name="csrfmiddlewaretoken"]').attr('value'));
fetch("/upload/", {
    method: 'POST',
    body: formData,
    credentials: 'same-origin',
})

Answer 2

Figured it out. The main issue here is that fetch does not automatically send cookies.

The solution is fairly simple - just add credentials: "same-origin" to your request and it should work fine (especially with the form data, albeit without the headers). Here is the revised and working code:

let formData = new FormData();
formData.append('file', file);;
formData.append('fileName', file.name);
// include form input from a hidden field elsewhere in the document
formData.append('csrfmiddlewaretoken', $('#csrf-helper input[name="csrfmiddlewaretoken"]').attr('value'));
fetch("/upload/", {
    method: 'POST',
    body: formData,
    credentials: 'same-origin',
})

Answer 3

Answer №2

Your inquiry is on the brink of triumph. Below is a way to handle it in a JSON format if you prefer not to use the form method. Also, kudos to @Cory for their smart form method.

Efficient method with a 3rd party library

let data = {
    'file': file,
    'fileName': file.name,
};
// To implement this, you'll need to download the 3rd party Cookies library
// https://docs.djangoproject.com/en/dev/ref/csrf/#ajax
let csrftoken = Cookies.get('csrftoken');
let response = fetch("/upload/", {
    method: 'POST',
    body: JSON.stringify(data),
    headers: { "X-CSRFToken": csrftoken },
})

2. Another approach that may seem complex, but doesn't require a 3rd party library

let data = {
    'file': file,
    'fileName': file.name,
};
let csrftoken = getCookie('csrftoken');
let response = fetch("/upload/", {
    method: 'POST',
    body: JSON.stringify(data),
    headers: { "X-CSRFToken": csrftoken },
})

// The below function is taken from 
// https://docs.djangoproject.com/en/dev/ref/csrf/#ajax
function getCookie(name) {
    var cookieValue = null;
    if (document.cookie && document.cookie !== '') {
        var cookies = document.cookie.split(';');
        for (var i = 0; i < cookies.length; i++) {
            var cookie = cookies[i].trim();
            // Checking if this cookie string starts with the desired name
            if (cookie.substring(0, name.length + 1) === (name + '=')) {
                cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                break;
            }
        }
    }
    return cookieValue;
}

Answer 4

Your inquiry is on the brink of triumph. Below is a way to handle it in a JSON format if you prefer not to use the form method. Also, kudos to @Cory for their smart form method.

Efficient method with a 3rd party library

let data = {
    'file': file,
    'fileName': file.name,
};
// To implement this, you'll need to download the 3rd party Cookies library
// https://docs.djangoproject.com/en/dev/ref/csrf/#ajax
let csrftoken = Cookies.get('csrftoken');
let response = fetch("/upload/", {
    method: 'POST',
    body: JSON.stringify(data),
    headers: { "X-CSRFToken": csrftoken },
})

2. Another approach that may seem complex, but doesn't require a 3rd party library

let data = {
    'file': file,
    'fileName': file.name,
};
let csrftoken = getCookie('csrftoken');
let response = fetch("/upload/", {
    method: 'POST',
    body: JSON.stringify(data),
    headers: { "X-CSRFToken": csrftoken },
})

// The below function is taken from 
// https://docs.djangoproject.com/en/dev/ref/csrf/#ajax
function getCookie(name) {
    var cookieValue = null;
    if (document.cookie && document.cookie !== '') {
        var cookies = document.cookie.split(';');
        for (var i = 0; i < cookies.length; i++) {
            var cookie = cookies[i].trim();
            // Checking if this cookie string starts with the desired name
            if (cookie.substring(0, name.length + 1) === (name + '=')) {
                cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                break;
            }
        }
    }
    return cookieValue;
}

Answer 5

Answer №3

If you're looking for a straightforward fix to this issue and don't want to rely on any external libraries, here's a solution you can implement directly in your template scripts.

fetch("your_post_url",
        {
            method: "POST",
            body: JSON.stringify(data),
            headers: { "X-CSRFToken": '{{csrf_token}}' },
        }
    ).then(res => {
        //process your response
    }

Answer 6

If you're looking for a straightforward fix to this issue and don't want to rely on any external libraries, here's a solution you can implement directly in your template scripts.

fetch("your_post_url",
        {
            method: "POST",
            body: JSON.stringify(data),
            headers: { "X-CSRFToken": '{{csrf_token}}' },
        }
    ).then(res => {
        //process your response
    }

Utilizing correct Django CSRF validation when making a fetch post request

Answer №1

Answer №2

Answer №3

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