Add async functions utils.
This commit is contained in:
parent
334a311c9e
commit
20c36f7c8b
1 changed files with 111 additions and 0 deletions
111
src/Async.tsx
Normal file
111
src/Async.tsx
Normal file
|
@ -0,0 +1,111 @@
|
||||||
|
import React, {useMemo, useState} from "react";
|
||||||
|
|
||||||
|
/**
|
||||||
|
* Asynchronous data state.
|
||||||
|
*/
|
||||||
|
interface AsyncState<T>
|
||||||
|
{
|
||||||
|
/**
|
||||||
|
* Determine if we are waiting for the promise result or not.
|
||||||
|
*/
|
||||||
|
pending: boolean;
|
||||||
|
/**
|
||||||
|
* The promise which is retrieved (or has retrieved) data.
|
||||||
|
*/
|
||||||
|
promise: Promise<T>;
|
||||||
|
/**
|
||||||
|
* Error thrown by the promise.
|
||||||
|
*/
|
||||||
|
error: Error;
|
||||||
|
/**
|
||||||
|
* The promise result.
|
||||||
|
*/
|
||||||
|
data: T;
|
||||||
|
}
|
||||||
|
|
||||||
|
/**
|
||||||
|
* A promise production function.
|
||||||
|
*/
|
||||||
|
export type PromiseFn<T> = () => Promise<T>;
|
||||||
|
|
||||||
|
/**
|
||||||
|
* React hook for promise result retrieval.
|
||||||
|
* @param promise The promise or a function that produces a promise.
|
||||||
|
* @param deps When one of the `deps` change, it will wait for the promise again.
|
||||||
|
*/
|
||||||
|
export function useAsync<T>(promise: Promise<T>|PromiseFn<T>, deps: any[] = []): AsyncState<T>
|
||||||
|
{
|
||||||
|
// Get the actual promise from the function if there is one.
|
||||||
|
if ((promise as PromiseFn<T>)?.call)
|
||||||
|
promise = (promise as PromiseFn<T>)();
|
||||||
|
else
|
||||||
|
promise = Promise.race([promise as Promise<T>]);
|
||||||
|
|
||||||
|
// The async state.
|
||||||
|
const [state, setState] = useState<AsyncState<T>>({
|
||||||
|
pending: true,
|
||||||
|
promise: promise,
|
||||||
|
error: undefined,
|
||||||
|
data: undefined,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* Partial update of an async state.
|
||||||
|
* @param stateUpdate A partial update object.
|
||||||
|
*/
|
||||||
|
const updateState = (stateUpdate: Partial<AsyncState<T>>) => {
|
||||||
|
// Copy the original state and apply the partial state update.
|
||||||
|
setState(Object.assign({}, state, stateUpdate));
|
||||||
|
};
|
||||||
|
|
||||||
|
// Reconfigure the promise when any deps have changed.
|
||||||
|
useMemo(() => {
|
||||||
|
(promise as Promise<T>).then((result) => {
|
||||||
|
// When there is a result, disable pending state and set retrieved data, without error.
|
||||||
|
updateState({
|
||||||
|
pending: false,
|
||||||
|
error: undefined,
|
||||||
|
data: result,
|
||||||
|
})
|
||||||
|
}).catch((error) => {
|
||||||
|
// An error happened, disable pending state, reset data, and set the error.
|
||||||
|
updateState({
|
||||||
|
pending: false,
|
||||||
|
error: error,
|
||||||
|
data: undefined,
|
||||||
|
})
|
||||||
|
});
|
||||||
|
|
||||||
|
// Promise is ready: reset the state to pending with the configured promise, without data and error.
|
||||||
|
updateState({
|
||||||
|
pending: true,
|
||||||
|
promise: promise as Promise<T>,
|
||||||
|
error: undefined,
|
||||||
|
data: undefined,
|
||||||
|
});
|
||||||
|
}, deps);
|
||||||
|
|
||||||
|
return state; // Return the current async state.
|
||||||
|
}
|
||||||
|
|
||||||
|
/**
|
||||||
|
* Wait for the promise to be fulfilled to render the children.
|
||||||
|
* @param async The async state.
|
||||||
|
* @param children Renderer function of the children, takes promised data as argument.
|
||||||
|
* @param fallback Content shown when the promise is not fulfilled yet.
|
||||||
|
* @constructor
|
||||||
|
*/
|
||||||
|
export function Await<T>({ async, children, fallback }: {
|
||||||
|
async: AsyncState<T>;
|
||||||
|
children: (async: T) => React.ReactElement;
|
||||||
|
fallback?: React.ReactElement;
|
||||||
|
})
|
||||||
|
{
|
||||||
|
// Still waiting for the promised data, showing fallback content.
|
||||||
|
if (async.pending) return fallback ?? <></>;
|
||||||
|
// An error happened, throwing it.
|
||||||
|
if (async.error) throw async.error;
|
||||||
|
|
||||||
|
// Promise is fulfilled, rendering the children with result data.
|
||||||
|
return children(async.data);
|
||||||
|
}
|
Loading…
Reference in a new issue