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AsyncCollectionLoaderT

import { type AsyncCollectionLoaderT } from '@dr.pogodin/react-global-state';

The AsyncCollectionLoaderT type is the signature of a valid data loader function for the useAsyncCollection() hook.

It is defined as a generic type:

type AsyncCollectionLoaderT<
  DataT,
  IdT extends number | string = number | string,
> = (id: IdT, oldData: DataT | null, meta: {
  abortSignal: AbortSignal;
  oldDataTimestamp: number;
}) => DataT | Promise<DataT | null> | null;
info
  • Prior to the library v0.22.0 the meta object passed into the loader included isAborted(), and setAbortCallback() methods. They have been removed in favor of the new abortSignal field.

Generic Parameters​

  • DataT — The type of data loaded by the loader function.
  • IdT — number | string — The type of collection item's index.

Arguments​

The data loader function receives two arguments:

  • id — IdT — The identifier of collection item to load.

  • oldData — DataT | null — The item previously loaded for this id, if any; or null.

  • meta — Holds additional information about the loading opeartion:

    • abortSignal — AbortSignal — Triggered if the loading operation has been aborted, and the return value of the current loader invokation will be ignored. For the optimal performance, the loader should react on this signal by terminating any asynchronous work early, and resolving null (or any other value).

    • oldDataTimestamp — number — Unix timestamp (milliseconds) of the given oldData, if any, or 0.

Result​

The data loader function, for the given ID, must return either DataT value, or null, or a Promise of DataT value or null. When a Promise is returned, the corresponding envelope in the global state is put into the (re-)loading state while the promise settlement is awaited; otherwise the value (DataT or null) is written into the envelope synchronously, without visiting the intermediate (re-)loading state.