With version 0.27.1 the request header will be lost, while 0.27.0 will not

[yangqixin123]

When sending a post request using version 0.27.1, the request header will be lost, but 0.27.0 will not
It is written as follows:

class Header {};
let myHeaders = new Header();
myHeaders["X-Foo"] = "bar";
myHeaders["X-Test"] = "test";
myHeaders["X-Time"] = Date.now();
  
axios.post('http://cors-test.appspot.com/test', { name: 'foo' }, { headers: myHeaders })
.then((res) => {
       console.log('res---',res.config.headers);
 })

See test.zip for details.

Environment

• Axios Version [0.27.1]
• Browser [Chrome]
• Browser Version [103.0.5060.114]
• Node.js Version [14.14]
• OS: [iOS 12.4]

test.zip

[techbirds]

You can use plain objects for parameter definitions, like this:

const myHeaders = {}
myHeaders["X-Foo"] = "bar";
myHeaders["X-Test"] = "test";
myHeaders["X-Time"] = Date.now();

axios.post('http://cors-test.appspot.com/test', {
    name: 'foo'
  }, {
    headers: myHeaders
  })
  .then((res) => {
    console.log('res---', res.config.headers);
  })

[yangqixin123]

But my project has been using the new Class writing method before. The official does not seem to mention that this writing method cannot be used in the new update.

[WillianAgostini]

Hello @yangqixin123

In this commit 910fdc1b1018, the method generateHTTPMethod

axios/lib/core/Axios.js

Lines 142 to 149 in 6b9b05b

	return this.request(mergeConfig(config || {}, {
	method: method,
	headers: isForm ? {
	'Content-Type': 'multipart/form-data'
	} : {},
	url: url,
	data: data
	}));

modified the behavior of this method, I believe that was not the intention.

I can commit by changing the way this merge happens and solving this problem.

[yangqixin123]

Hello @yangqixin123

In this commit 910fdc1b1018, the method generateHTTPMethod

axios/lib/core/Axios.js

Lines 142 to 149 in 6b9b05b

	return this.request(mergeConfig(config || {}, {
	method: method,
	headers: isForm ? {
	'Content-Type': 'multipart/form-data'
	} : {},
	url: url,
	data: data
	}));

modified the behavior of this method, I believe that was not the intention.
I can commit by changing the way this merge happens and solving this problem.

@WillianAgostini WillianAgostini ok i will be very grateful

[WillianAgostini]

@yangqixin123 , you can workaround returning casting variable myHeaders like a generic object.

  myHeaders = {...myHeaders};

[yangqixin123]

@WillianAgostini I tried this and it's ok, but the company's previous production environment project does not want to be changed because of the upgrade of axios, I hope the official modification can be compatible with the previous usage

[WillianAgostini]

@yangqixin123, I created an PR #4871.

[yangqixin123]

@WillianAgostini ok i will be very grateful

[jasonsaayman]

Closing as it merged