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Experimental WebAPI

SafeFetch

Types

bodyError

Describes a rejected native response body reader.

Function results expose [> bodyError] so body errors can compose with fetch and application errors.

type bodyError = [#BodyReadRejected(readError)]

fetchError

Describes an expected failure while producing or classifying a response.

  • #FetchRejected(cause) means the native Fetch operation threw or its promise rejected. Fetch does not expose a reliable browser-independent distinction between network, abort, permission, and other request failures. The exn preserves the original JavaScript rejection value; use JsExn.fromException to retrieve it. A custom abort reason can be any JavaScript value, so the cause is not restricted to JsError.t.
  • #ResponseNotOk({response}) means Fetch fulfilled with a response whose ok field is false. The response remains available for inspection and body reading.

Function results expose [> fetchError] so these errors can compose with errors from body readers and application decoders.

type fetchError = [
  | #FetchRejected(exn)
  | #ResponseNotOk(httpError)
]

httpError

Describes a response whose ok field is false.

The original response is retained so callers can inspect its status, headers, and body.

type httpError = {response: WebAPI.Response.t}

Record fields

response
WebAPI.Response.t

readError

Describes a rejected response body reader.

The record retains both the response whose body was being consumed and the original rejection cause.

type readError = {response: WebAPI.Response.t, cause: exn}

Record fields

response
WebAPI.Response.t
cause
exn

response

A successfully read body paired with its original response.

The response body has been consumed. Clone the response before reading when another consumer also needs the body.

type response<'body> = {
  response: WebAPI.Response.t,
  body: 'body,
}

Record fields

response
WebAPI.Response.t
body
'body

Values

arrayBuffer

Reads the response body as an ArrayBuffer.t.

Returns the body with the original response, or a bodyError when the native reader rejects.

let arrayBuffer: WebAPI.Response.t => promise<
  result<response<ArrayBuffer.t>, [> bodyError]>,
>

Parameters

WebAPI.Response.t

Return type

promise<result<response<Stdlib.ArrayBuffer.t>>>

blob

Reads the response body as a Blob.t.

Returns the body with the original response, or a bodyError when the native reader rejects.

let blob: WebAPI.Response.t => promise<
  result<response<WebAPI.Blob.t>, [> bodyError]>,
>

Parameters

WebAPI.Response.t

Return type

promise<result<response<WebAPI.Blob.t>>>

bytes

Reads the response body as an array of bytes.

Returns the body with the original response, or a bodyError when the native reader rejects.

let bytes: WebAPI.Response.t => promise<
  result<response<array<int>>, [> bodyError]>,
>

Parameters

WebAPI.Response.t

Return type

promise<result<response<array<int>>>>

checkOk

Classifies an existing response using its native ok field.

Returns Ok(response) for successful responses and Error(#ResponseNotOk({response})) otherwise. This function does not read the body and is useful with responses obtained from the raw Fetch API.

let checkOk: WebAPI.Response.t => result<
  WebAPI.Response.t,
  [> #ResponseNotOk(httpError)],
>

Parameters

WebAPI.Response.t

Return type

result<WebAPI.Response.t>

fetch

Fetches a URL and returns expected request and HTTP status failures as values.

The returned promise fulfills with Error(#FetchRejected(cause)) when the native operation throws or rejects, Error(#ResponseNotOk({response})) when the response is not OK, or Ok(response) for an OK response.

let fetch: (
  string,
  ~init: WebAPI.Request.requestInit=?,
) => promise<result<WebAPI.Response.t, [> fetchError]>>

Parameters

stringoption<WebAPI.Request.requestInit>

Return type

promise<result<WebAPI.Response.t>>

fetchWithRequest

Fetches an existing Request.t and returns expected request and HTTP status failures as values.

This has the same result contract as fetch and accepts an optional request initializer that is passed to the native Fetch operation.

let fetchWithRequest: (
  WebAPI.Request.t,
  ~init: WebAPI.Request.requestInit=?,
) => promise<result<WebAPI.Response.t, [> fetchError]>>

Parameters

WebAPI.Request.toption<WebAPI.Request.requestInit>

Return type

promise<result<WebAPI.Response.t>>

formData

Reads the response body as FormData.t.

Returns the body with the original response, or a bodyError when the native reader rejects.

let formData: WebAPI.Response.t => promise<
  result<response<WebAPI.FormData.t>, [> bodyError]>,
>

Parameters

WebAPI.Response.t

Return type

promise<result<response<WebAPI.FormData.t>>>

json

Parses the response body as JSON.t.

Malformed JSON and other native reader rejections become bodyError values. This function does not validate the parsed JSON against an application domain type.

let json: WebAPI.Response.t => promise<
  result<response<JSON.t>, [> bodyError]>,
>

Parameters

WebAPI.Response.t

Return type

promise<result<response<Stdlib.JSON.t>>>

text

Reads the response body as a string.

Returns the body with the original response, or a bodyError when the native reader rejects.

let text: WebAPI.Response.t => promise<
  result<response<string>, [> bodyError]>,
>

Parameters

WebAPI.Response.t

Return type

promise<result<response<string>>>