implement FSA errors by setting error to true if payload is an Error obj

[ngokevin]

Noticed this spec of FSA wasn't yet implemented, and there's an issue for it.

This sets action.error to true if the payload is a direct instance of Error. This is the faintest touch of magic, but if it's documented, it makes sense.

Also fixes a possible error where we're trying to set action.meta even though action is a const.

r? @acdlite

[acdlite]

Not sure about this... Feels like it's outside the scope of the module. if the payload is an error, that means someone caught the error and placed it there. Shouldn't it be up to them to set error to true?

[ngokevin]

But there doesn't seem to be a way to set error to true with createAction. The only thing that can be set by the user is type and payload.

[acdlite]

Oh duh I see what you mean. I was thinking about handleAction() for some reason — actually I dunno what I was thinking.

This seems reasonable then.

[acdlite]

This check won't work for subclasses of Error (e.g. TypeError)

[ngokevin]

Ah thanks, updated to use instanceof.

[ngokevin]

Updated to use instanceof

[ricardofbarros]

+1

[krasnoperov]

+1

[cappslock]

+1

[tkqubo]

+1

[jonny-improbable]

+1, please can you consider releasing this, @acdlite?

[bravewick]

+1

[pbomb]

I'm running into this issue now as well. Is this issue expected to be resolved soon?

[tokenvolt]

+1

[danilotorrisi]

I've also had the same issue, I hope it's gonna be released soon!

[lukewestby]

What is the reason for changing this from const to let?

[ngokevin]

i guess i didn't have to. thought maybe i should since we modify action below, but we don't reassign.

[lukewestby]

To me it's less about the semantics of the keyword and more about consistency with the rest of the code base. const is used whenever a variable does not need to be reassigned.

[lukewestby]

@ngokevin this is awesome, thanks for submitting! Can you update the README to document your change?

Can anyone think of a scenario where this would be a breaking change? I can't think of anything but if anyone can then we will need @acdlite's input before merging.

[ngokevin]

@lukewestby thanks for checking it out, updated.

[Strate]

👍

[kpaxqin]

@ngokevin
seems we can't customize the error object by payloadCreator.
maybe we can do in this way

export default function createAction(type, actionCreator, metaCreator) {
  const finalActionCreator = typeof actionCreator === 'function'
    ? actionCreator
    : identity;

  return (...args) => {
    const payload = finalActionCreator(...args)
    const action = {
      type,
      payload,
      error: (payload instanceof Error)
    };

    if (typeof metaCreator === 'function') {
      action.meta = metaCreator(...args);
    }

    return action;
  };
}

[acdlite]

Huzzah! I finally got off my ass and merged this! Thanks!

[kpaxqin]

@acdlite
I've create a PR to set error to true when payloadCreator return Error object.
see: #43