Add AxiosException class

[ruscon]

Is your feature request related to a problem? Please describe.
I use typescript.
How to verify that I received exactly axios error?

Describe the solution you'd like
Add custom error class: AxiosException, which is inherited from the standard Error class

Example

try {
  axios.get('...')
}
catch(err) {
  if (err instanceof AxiosException) {
      console.error(err.response);
  }
}

[chinesedfan]

How about checking error.isAxiosError directly?

[ruscon]

@chinesedfan
Typescript needs typing.
The typification of the class Error does not know anything about this property.
and the interface in this case also does not work normally.
Those, the only option is a class

[chinesedfan]

@ruscon I think you can use type assertion.

import axios, {AxiosError} from 'axios';

try {
  axios.get('...')
}
catch(err) {
  if ((<any>err).isAxiosError) { // check to make sure type assertion is right
      const e = <AxiosError>error;
      console.error(e.response);
  }
}

[ruscon]

@chinesedfan So you can do something like this:

import axios, {AxiosError} from 'axios';

try {
    axios.get('...')
}
catch(err) {
    if (err.isAxiosError) { // no types
        const e: AxiosError = error;
        console.error(e.response);
    }
}

But this is a bad approach for both js and ts.

[ruscon]

@chinesedfan https://medium.com/@xjamundx/custom-javascript-errors-in-es6-aa891b173f87

[chinesedfan]

But this is a bad approach for both js and ts.

@ruscon I agree a bit in ts, but not in js. There are so many duck types in js. I think that's why ts designs type assertion. Your AxiosException approach is a standard but heavy way. If someday axios were totally refactored, I will stand in your side. Good luck!

[ruscon]

@chinesedfan heavy way ?

[chinesedfan]

@ruscon heavy means extra changes. I am not a native speaker and don't know whether it has strange meanings in English.

[ruscon]

@chinesedfan, me too, no problems.

I made all the changes, as you can see, is nothing heavy there.
If classes can be used, then I would even more logic here
e8ddb60#diff-c08f94705d80a1dab0bdb72bbdd83daa

It will be something like this

module.exports = class AxiosException extends Error {   
    constructor(error) {
        var json = error.toJSON();
        json.name = AxiosException.name;

        super(JSON.stringify(json, undefined, 2));

        Object.assign(this, error);
    }
}

[AyushG3112]

I think this was sorted with #1415 but a release is pending

[Kunamatata]

What's the state of having AxiosError be a class as well as an interface in order to be able to use instanceof ?

[sammy007]

OMG. 1 year of jerking with it.

[fubar]

Is there any progress on this? AxiosError is useless as it is in Typescript.

[Klemensas]

Having a specific exception would be nice but AxiosError is definitely not useless.
You can write a helper around it, something like:

export function isAxiosError<T>(error: AxiosError | any): error is AxiosError<T> {
  return error && error.isAxiosError
}

And then use it like this:

  catch (exception) {
    if (isAxiosError<apiTypes.ResponseError>(exception) && exception.response) {
       ...
    }
  }

[jasonsaayman]

Resolved in #2014

[darkbasic]

@jasonsaayman did it land in any currently released version?

[aeharding]

@darkbasic I don't think so. I have to add the sha to my package.json:

"axios": "https://github.com/axios/axios.git#58112e137e316c7154e77a3b3777d6788de869b9",

I ran into this issue because Typescript 4.4 defaults catch {} error type to unknown instead of any now, and checking error instanceof AxiosException is the cleanest way to fix it.

[darkbasic]

Me either.

[CatsMiaow]

You can apply type guards with the isAxiosError helper function.

axios/index.d.ts

Line 168 in f3ca637

isAxiosError(payload: any): payload is AxiosError;

axios/test/typescript/axios.ts

Lines 369 to 372 in f3ca637

	.catch((error) => {
	if (axios.isAxiosError(error)) {
	const axiosError: AxiosError = error;
	}

import axios from 'axios';

if (axios.isAxiosError(error)) {
  // error.response?.data ...
}

[darkbasic]

That's what I did, but having to write your own type guard sucks :)