Configuration options
These can be passed in an object to
useAsync(options), or as props to <Async {...options}> and custom instances.useFetch additionally takes these options:Promise
A Promise instance which has already started. It will simply add the necessary resolve/reject callbacks and set
startedAt to the time promise was first provided. Changing the value of promise will cancel any pending promise and listen to the new one. If promise is initially undefined, the React Async state will be pending.Note thatreloadwill not do anything when usingpromise. UsepromiseFninstead.
function(props: Object, controller: AbortController): Promise
A function that returns a promise. It is automatically invoked in
componentDidMount and componentDidUpdate. The function receives all component props (or options) and an AbortController instance as arguments.Be aware that updatingpromiseFnwill trigger it to cancel any pending promise and load the new promise. Passing an inline (arrow) function will cause it to change and reload on every render of the parent component. You can avoid this by defining thepromiseFnvalue outside of the render method. If you need to pass variables to thepromiseFn, pass them as additional props to<Async>, aspromiseFnwill be invoked with these props. Alternatively you can useuseCallbackor memoize-one to avoid unnecessary updates.
function(args: any[], props: Object, controller: AbortController): Promise
A function that returns a promise. This is invoked only by manually calling
run(...args). Any arguments to run are passed-through as an array via args, so you can pass data through either args or props, as needed. The deferFn is commonly used to send data to the server following a user action, such as submitting a form. You can use this in conjunction with promiseFn to fill the form with existing data, then updating it on submit with deferFn.Be aware that when using bothpromiseFnanddeferFn, the shape of their fulfilled value should match, because they both update the samedata.
any
Watches this property through
componentDidUpdate and re-runs the promiseFn when the value changes, using a simple reference check (oldValue !== newValue). If you need a more complex update check, use watchFn instead.function(props: Object, prevProps: Object): boolean | any
Re-runs the
promiseFn when this callback returns truthy (called on every update). Any default props specified by createInstance are available too.any | Error
Initial state for
data or error (if instance of Error); useful for server-side rendering. When an initialValue is provided, the promiseFn will not be invoked on first render. Instead, status will be immediately set to fulfilled or rejected and your components will render accordingly. If you want to trigger the promiseFn regardless, you can call reload() or use the watch or watchFn option.Note thatonResolveoronRejectis not invoked in this case and nopromiseprop will be created.
function(data: any): void
Callback function invoked when a promise resolves, receives data as argument.
function(reason: Error): void
Callback function invoked when a promise rejects, receives rejection reason (error) as argument.
function(): void
Callback function invoked when a promise is cancelled, either manually using
cancel() or automatically due to props changes or unmounting.function(state: any, action: Object, internalReducer: function(state: any, action: Object))
State reducer to take full control over state updates by wrapping the internal reducer. It receives the current state, the dispatched action and the internal reducer. You probably want to invoke the internal reducer at some point.
This is a power feature which loosely follows the state reducer pattern. It allows you to control state changes by intercepting actions before they are handled, or by overriding or enhancing the reducer itself.
function(action: Object, internalDispatch: function(action: Object), props: Object)
Action dispatcher to take full control over action dispatching by wrapping the internal dispatcher. It receives the original action, the internal dispatcher and all component props (or options). You probably want to invoke the internal dispatcher at some point.
This is a power feature similar to the state reducer pattern. It allows you to control state changes by intercepting actions before they are dispatched, to dispatch additional actions, possibly later in time.
string
A unique label to describe this React Async instance, used in React DevTools (through
useDebugValue) and React Async DevTools.boolean
Enables experimental Suspense integration. This will make React Async throw a promise while loading, so you can use Suspense to render a fallback UI, instead of using
<IfPending>. Suspense differs in 2 main ways:<Suspense>should be an ancestor of your Async component, instead of a descendant. It can be anywhere up in thecomponent hierarchy.- You can have a single
<Suspense>wrap multiple Async components, in which case it will render the fallback UI untilall promises are settled.
Note that the way Suspense is integrated right now may change. Until Suspense for data fetching is officially released, we may make breaking changes to its integration in React Async in a minor or patch release. Among other things, we'll probably add a cache of sorts.
boolean
Enables the use of
deferFn if true, or enables the use of promiseFn if false. By default this is automatically chosen based on the request method (deferFn for POST / PUT / PATCH / DELETE, promiseFn otherwise).boolean
Enables or disables JSON parsing of the response body. By default this is automatically enabled if the
Accept header is set to "application/json".Last modified 2yr ago