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RemoteData and WebData to use with bs-fetch for BuckleScript

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RemoteData and WebData to use with bs-fetch and bs-json for BuckleScript

Test status

RemoteData.t is a simple variant type that allows you to store a data that can have 4 potential states:

  • Success('a): your data has been successfully retrieved and stored
  • Failure('e): your data could not be retrieved
  • Loading: your data is beeing fetched
  • NotAsked: you didn't fetch your data yet

This type provides you many usefull functions to handle your data: map, andThen, withDefault, fromOption, fromResult, fromPromise, ...

The main goal for this type is to be used for HTTP requests. That's where WebData comes into play. WebData.t is a RemoteData.t type but with the error type specified as a WebData.error. The WebData module provides some usefull functions to fetch data from API and convert it to a WebData.t. You can even provide your own Json decoder to convert the result of your API call to a WebData.t of any type you want/need.


type person = {
  age: int,
  name: string

module Decode = {
  let personDecoderExn = json =>
      age: json |> field("age", int),
      name: json |> field("name", string)
  let personDecoder = json =>
    try (Belt.Result.Ok(personDecoderExn(json))) {
    | Json.Decode.DecodeError(err) => Belt.Result.Error(err)

/* At app launch say you set your data state to `NotAsked` */
let data: WebData.t(person) = RemoteData.NotAsked;

/* You received an event and you need to retrieve your data */
let data: WebData.t(person) = RemoteData.Loading;

|> WebData.fromResponse(Decode.personDecoder)
|> Js.Promise.then_(data => {
  /* Here your data is still a WebData.t(person) and will be
    either Success(person), or Failure(httpError) */


npm install --save bs-remotedata

Then add bs-remotedata to bs-dependencies in your bsconfig.json:

  "bs-dependencies": ["bs-remotedata"]


For the moment, please see the interface files: