Expiry Policy
By default, Rest Hooks cache policy can be described as stale-while-revalidate. This means that when data is available it can avoid blocking the application by using the stale data. However, in the background it will still refresh the data if old enough.
To explain these concepts we'll be faking an endpoint that gives us the current time so it is easy to tell how stale it is.
class TimedEntity extends Entity {
id = '';
updatedAt = new Date(0);
pk() {
return this.id;
}
static schema = {
updatedAt: Date,
};
}
const lastUpdated = new RestEndpoint({
path: '/api/currentTime/:id',
schema: TimedEntity,
});
Expiry status
Fresh
Data in this state is considered new enough that it doesn't need to fetch.
Stale
Data is still allowed to be shown, however Rest Hooks might attempt to revalidate by fetching again.
useSuspense() considers fetching on mount as well as when its parameters change. In these cases it will fetch if the data is considered stale.
Invalid
Data should not be shown. Any components needing this data will trigger fetch and suspense. If no components care about this data no action will be taken.
Expiry Time
Endpoint.dataExpiryLength
Endpoint.dataExpiryLength sets how long (in miliseconds) it takes for data to transition from 'fresh' to 'stale' status. Try setting it to a very low number like '50' to make it becomes stale almost instantly; or a very large number to stay around for a long time.
Toggling between 'first' and 'second' changes the parameters. If the data is still considered fresh you will continue to see the old time without any refresh.
response({id}){return{id,updatedAt:new Date().toISOString()};}
import { lastUpdated } from './api/lastUpdated';const getUpdated = lastUpdated.extend({ dataExpiryLength: 10000 });function TimePage({ id }) {const { updatedAt } = useSuspense(getUpdated, { id });return (<div>API Time:{' '}<time>{Intl.DateTimeFormat('en-US', { timeStyle: 'long' }).format(updatedAt)}</time></div>);}function Navigator() {const [id, setId] = React.useState('1');const handleChange = e => setId(e.currentTarget.value);return (<div><div><button value="1" onClick={handleChange}>First</button><button value="2" onClick={handleChange}>Second</button></div><TimePage id={id} /><div>Current Time: <CurrentTime /></div></div>);}render(<Navigator />);
@rest-hooks/rest
Examples
To apply to all of a Resource's endpoints, use getEndpointExtra
Long cache lifetime
import { RestEndpoint, RestGenerics, createResource } from '@rest-hooks/rest';
// We can now use LongLivingEndpoint to create endpoints that will be cached for one hour
class LongLivingEndpoint<O extends RestGenerics> extends RestEndpoint<O> {
dataExpiryLength = 60 * 60 * 1000; // one hour
}
const LongLivingResource = createResource({
path: '/:id',
Endpoint: LongLivingEndpoint,
});
Never retry on error
import { RestEndpoint, RestGenerics, createResource } from '@rest-hooks/rest';
// We can now use NoRetryEndpoint to create endpoints that will be cached for one hour
class NoRetryEndpoint<O extends RestGenerics> extends RestEndpoint<O> {
errorExpiryLength = Infinity;
}
const NoRetryResource = createResource({
path: '/:id',
Endpoint: NoRetryEndpoint,
});
Endpoint.invalidIfStale
Endpoint.invalidIfStale eliminates the stale
status, making data
that expires immediately be considered 'invalid'.
This is demonstrated by the component suspending once its data goes stale. If the data is still within the expiry time it just continues to display it.
response({id}){return{id,updatedAt:new Date().toISOString()};}
import { lastUpdated } from './api/lastUpdated';const getUpdated = lastUpdated.extend({invalidIfStale: true,dataExpiryLength: 5000,});function TimePage({ id }) {const { updatedAt } = useSuspense(getUpdated, { id });return (<div>API Time:{' '}<time>{Intl.DateTimeFormat('en-US', { timeStyle: 'long' }).format(updatedAt)}</time></div>);}function Navigator() {const [id, setId] = React.useState('1');const handleChange = e => setId(e.currentTarget.value);return (<div><div><button value="1" onClick={handleChange}>First</button><button value="2" onClick={handleChange}>Second</button></div><TimePage id={id} /><div>Current Time: <CurrentTime /></div></div>);}render(<Navigator />);
Force refresh
Controller.fetch can be used to trigger a fetch while still showing the previous data. This can be done even with 'fresh' data.
response({id}){return{id,updatedAt:new Date().toISOString()};}
import { lastUpdated } from './api/lastUpdated';function ShowTime() {const { updatedAt } = useSuspense(lastUpdated, { id: '1' });const ctrl = useController();return (<div><time>{Intl.DateTimeFormat('en-US', { timeStyle: 'long' }).format(updatedAt)}</time>{' '}<button onClick={() => ctrl.fetch(lastUpdated, { id: '1' })}>Refresh</button></div>);}render(<ShowTime />);
Invalidate (re-suspend)
Both endpoints and entities can be targetted to be invalidated.
A specific endpoint
In this example we can see invalidating the endpoint shows the loading fallback since the data is not allowed to be displayed.
response({id}){return{id,updatedAt:new Date().toISOString()};}
import { AsyncBoundary } from '@rest-hooks/react';import { lastUpdated } from './api/lastUpdated';import ShowTime from './ShowTime';import Loading from './Loading';function Demo() {const ctrl = useController();return (<div><AsyncBoundary fallback={<Loading id="1" />}><ShowTime id="1" /></AsyncBoundary><AsyncBoundary fallback={<Loading id="2" />}><ShowTime id="2" /></AsyncBoundary><AsyncBoundary fallback={<Loading id="3" />}><ShowTime id="3" /></AsyncBoundary><button onClick={() => ctrl.invalidateAll(lastUpdated)}>Invalidate All</button><button onClick={() => ctrl.invalidate(lastUpdated, { id: '1' })}>Invalidate First</button></div>);}render(<Demo />);
Any endpoint with an entity
Using Invalidate allows us to invalidate any endpoint that includes that relies on that entity in their response. If the endpoint uses the entity in an Array, it will simply be removed from that Array.
response({id}){return{id,updatedAt:new Date().toISOString()};}
response({id}){return{id};}
import { lastUpdated, TimedEntity } from './api/lastUpdated';export const deleteLastUpdated = new RestEndpoint({path: '/api/currentTime/:id',method: 'DELETE',schema: new schema.Invalidate(TimedEntity),});function ShowTime() {const { updatedAt } = useSuspense(lastUpdated, { id: '1' });const ctrl = useController();return (<div><time>{Intl.DateTimeFormat('en-US', { timeStyle: 'long' }).format(updatedAt)}</time>{' '}<button onClick={() => ctrl.fetch(deleteLastUpdated, { id: '1' })}>Delete</button><button onClick={() => ctrl.setResponse(deleteLastUpdated, { id: '1' }, { id: '1' })}>Delete (with no fetch)</button></div>);}render(<ShowTime />);
Controller.fetch() lets us update the server and store. We can use Controller.setResponse() for cases where we simply want to change the local store without updating the server.
Error policy
Endpoint.errorPolicy controls cache behavior upon a fetch rejection. It uses the rejection error to determine whether it should be treated as 'soft' or 'hard' error.
Soft
Soft errors will not invalidate a response if it is already available. However, if there is currently no data available, it will mark that endpoint as rejected, causing useSuspense() to throw an error. This can be caught with NetworkErrorBoundary
Hard
Hard errors always invalidate a response with the rejection - even when data has previously made available.
response({id}){return{id,updatedAt:new Date().toISOString()};}
import { lastUpdated } from './api/lastUpdated';let FAKE_ERROR: Error | undefined = undefined;const superFetch = lastUpdated;const mockErrorFetch = arg =>FAKE_ERROR !== undefined ? Promise.reject(FAKE_ERROR) : superFetch(arg);const getUpdated = lastUpdated.extend({fetch: mockErrorFetch,errorPolicy: error =>error.status >= 500 ? ('soft' as const) : ('hard' as const),});function createError(status) {const error: Error & { status: any } = new Error('fake error') as any;error.status = status;return error;}function ShowTime() {const { updatedAt } = useSuspense(getUpdated, { id: '1' });const ctrl = useController();React.useEffect(() => () => {FAKE_ERROR = undefined;},[updatedAt],);return (<div><time>{Intl.DateTimeFormat('en-US', { timeStyle: 'long' }).format(updatedAt)}</time>{' '}<div><buttononClick={() => {FAKE_ERROR = createError(500);ctrl.fetch(getUpdated, { id: '1' });}}>Fetch Soft</button><buttononClick={() => {FAKE_ERROR = createError(400);ctrl.fetch(getUpdated, { id: '1' });}}>Fetch Hard</button><buttononClick={() => {FAKE_ERROR = createError(500);ctrl.invalidate(getUpdated, { id: '1' });}}>Invalidate Soft</button><buttononClick={() => {FAKE_ERROR = createError(400);ctrl.invalidate(getUpdated, { id: '1' });}}>Invalidate Hard</button></div></div>);}render(<ResetableErrorBoundary><ShowTime /></ResetableErrorBoundary>,);
Policy for RestEndpoint
Since 500
s indicate a failure of the server, we want to use stale data
if it exists. On the other hand, something like a 400
indicates 'user error', which
means the error indicates something about application flow - like if a record is deleted, resulting
in 400
. Keeping the record around would be inaccurate.
Since this is the typical behavior for REST APIs, this is the default policy in @rest-hooks/rest
errorPolicy(error) {
return error.status >= 500 ? 'soft' : undefined;
}