bs-use-fetch

A ReasonReact useFetch hook. It:

• wraps bs-fetch
• is composable
  • uses a result type
  • makes impossible state irrepresentable
  • lets you use a JSON decoding library of your choice
  • lets you compose fetch errors and decoding error via polymorphic variants

It seems workable, especially for getting data, but expect some breaking changes before v1.0.

Basic usage

[@react.component]
let make = () => {
  UseFetch.(
    // fetch the data
    useFetch(
      "https://api.github.com/search/repositories?q=language:reason&sort=stars&order=desc",
    )
    // use whichever decoding library you like
    ->mapOk(r => GhRepo.t_decode(r)->Decode.mapDecodingError)
    ->(
        // below, no distinction is made between fetching and refetching,
        // but you're free to make other UX choices
        fun
        | Fetching => ReasonReact.string("Loading...")
        | Refetching(Ok(({items}: GhRepo.t)))
        | Complete(Ok(({items}: GhRepo.t))) =>
          <ul>
            {Belt.Array.map(items, ({fullName, htmlUrl}: GhRepo.repo) =>
               <li key=fullName>
                 <a href=htmlUrl> {ReasonReact.string(fullName)} </a>
               </li>
             )
             ->React.array}
          </ul>
        | Refetching(Error(`FetchError(_)))
        | Complete(Error(`FetchError(_))) =>
          <h2> {ReasonReact.string("Fetch error!")} </h2>
        | Refetching(Error(`DecodeError((err: Decco.decodeError))))
        | Complete(Error(`DecodeError((err: Decco.decodeError)))) =>
          <h2> {ReasonReact.string("Decode error!")} </h2>
  );
};

(See the full example in /examples.)

Or, if you prefer the style prevalent in JS-land,

  let (loading, data, error) = UseFetch.(
    useFetch(
      "https://api.github.com/search/repositories?q=language:reason&sort=stars&order=desc",
    )
    ->mapOk(r => GhRepo.t_decode(r)->Decode.mapDecodingError)
    ->toLoadingDataAndError
  );

  // ...

Documentation

See UseFetch.rei.

TODOs

• Add request/init parameters
• Support submitting
• toLoadingAndResult helper
• use AbortController (bs-fetch has a stale PR for same)
• tests (will probably require bindings for something like jest-fetch-mock)
• Generate API docs (the comments in the .rei should already be odoc-compatible.
• React Suspense compatibility?