Add support for async transformRequest

Hello, I have a feature request to this project. It would be great if you could add support for async transformRequest functions.

The goal I want to achieve is to add oauth2 token to the authorization header, but this token must be fetched from external service, and sometimes must be refreshed, so the function which manages it is asynchronous.

It’d be great if that code could work:

        const instance = axios.create({
            transformRequest: [async function (data, headers) {
                headers['Authorization'] = 'Bearer ' + await loginService.getToken()
            }],
        });

[baijunjie]

interceptors.request support for async function.

axios.interceptors.request.use(async function (options) {
    options.headers['Authorization'] = await getToken();
    return options;
}, function (error) {
    console.log('Request error: ', error);
    return Promise.reject(error);
});

[amoshydra]

Looks like @baijunjie has already mentioned interceptor. Sorry, I didn’t read the thread properly…

original

Hi, I don’t think the proposed solution work. Not sure why this issue is closed though…

Looking at how transformRequest is used in transformData, returning a Promise inside transformRequest may yield incorrect result. https://github.com/axios/axios/blob/203cbc2da0ef0f68d517ba2a6176df1d48efc2fb/lib/core/transformData.js#L13-L20

I don’t think transformRequest allow async operation out of the box.

Alternative?

However, I think the requirements from both @aartek and @baijunjie can be fulfilled with Axios’ request interceptor?

axios.interceptors.request.use(async (config) => {
  config.headers['Authorization'] = 'Bearer ' + await loginService.getToken()
  return config;
})