Resource Status

Defines the ResourceStatusT type and utilities operating on this type.

Install

yarn add @freckle/resource-status

Versioning and release process

See RELEASE.md.

ResourceStatusT<R>

Wraps data from a resource R with metadata to describe the status of accessing and updating the data. The status field can be used to react accordingly:

type Props = {resource: ResourceStatusT<{username: string}>}
const UserView = ({resource}: Props) => {
  switch (resource.status) {
    case 'idle':
      return <p>User has not been loaded</p>
    case 'loading':
      return <p>Loading user</p>
    case 'reloading':
      return <p>User: {resource.data.username} (reloading)</p>
    case 'error':
      return (
        <p>
          Error loading user: <pre>{JSON.stringify(resource.error)}</pre>
        </p>
      )
    case 'complete':
      return <p>User: {resource.data.username}</p>
    case 'updating':
      return <p>User: {resource.data.username} (pending update)</p>
    case 'updating-error':
      return (
        <p>
          Error updating user {resource.data.username}: <pre>{JSON.stringify(resource.error)}</pre>
        </p>
      )
    default:
      return exhaustive(resource)
  }
}

Utilities

Utilities are defined to make operating on a resource status.

maybeResourceData(resource)

Returns the underlying resource.data if it exists.

fromMaybeResourceData(resource, default)

Returns the underlying resource.data if it exists, or default otherwise.

isFetching(resource)

Returns true when a resource is loading or reloading.

updateResource(resource, updateFn)

Performs updateFn(resource.data) if there exists data in the resource, and returns a new resource. This is convenient for reducer-style updates:

type State = ResourceStatusT<{username: string; token: string}>
type Action =
  | {type: 'USER_UPDATE_REQUEST'}
  | {type: 'USER_UPDATE_RESPONSE'; data: {username: string}}

const reducer = (state: State, action: Action) => {
  switch (action.type) {
    case 'USER_UPDATE_REQUEST':
    // ...
    case 'USER_UPDATE_RESPONSE':
      return updateResource(state, user => ({
        ...user,
        username: action.data.username
      }))
  }
}

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LICENSE