Changed FSA type dispatched on network errors to failureType

[sgoll]

Please see issue #25 for the rationale behind this pull request.

Basically, we want to make sure that the following invariant always holds true: for each [CALL_API] action that is handled by redux-api-middleware,

• exactly one request FSA is dispatched, and
• that request FSA is followed by either:
  • nothing (when the request FSA had its error property set), or
  • either a single success FSA or a single failure FSA (when the request FSA had its error property unset).

The actual code change is literally a single line, but the accompanying documentation change is rather more elaborate and might require some review.

Also, since the third argument res might now be either present or absent from the failure type descriptor's custom payload and meta properties (when using functions), this change is not backward compatible.

[barrystaes]

I agree with your point.
There should be only 1 request and errors should be in a failure FSA.

About the implementation;

• I dont really understand the "res" sidenote you end with.
• Should we do the same for the FSA resulting from a bailout which also used the requestType?
• Are there more places requestType is used to return errors?
• There is a merge conflict in this PR. Could you rebase it to the latest version?

And since this touches functionality i'd like @agraboso to give a green light for merging.

[sgoll]

I updated the pull request.

@barrystaes:

Previously the following invariant was true: when the failure type descriptor defines custom payload and meta functions, those are called with three arguments: (action, state, res). With the changes done in this PR, this is no longer true: res might not be available when issuing a failure FSA, i.e. those functions might receive res === undefined. This may or may not be a problem.

Regarding your first question: I think it is okay to bail out with an error'd request FSA. The motivation for this issue was only that there could be multiple request FSAs. However, when the (only) request FSA received is marked as error that would be okay with me. It's only the two request FSAs (first without error, second with error) that I have a problem with and which should be fixed by this PR.

[barrystaes]

Better late than never: thank you for the PR update.
Ok i now understand this is not about the request FSA with error flag.

Since this is a breaking change, this PR should go to the next v2.0.0-beta branch (instead of v1.1.x). @sgoll what do you think? Also, i wonder i you/anyone uses these changes in production?

[johnwiseheart]

Any update on this?

[nason]

This will be changed in #175