RTK Query cache utils. Useful abstractions for creating `provides`/`invalidates` cache data tags against endpoints.

rtkQueryCacheUtils.ts

import { FetchBaseQueryError } from '@rtk-incubator/rtk-query/dist';

/**
 * Default tags used by the cacher helpers
 */
const defaultTags = ["UNAUTHORIZED", "UNKNOWN_ERROR"] as const;
type DefaultTags = typeof defaultTags[number];

function concatErrorCache<T, ID>(
  existingCache: CacheList<T, ID>,
  error: FetchBaseQueryError | undefined
): CacheList<T, ID> {
  if (error && "status" in error && error.status === 401) {
    // unauthorized error
    return [...existingCache, "UNAUTHORIZED"];
  }

  // unknown error
  return [...existingCache, "UNKNOWN_ERROR"];
}

/**
 * An individual cache item
 */
export type CacheItem<T, ID> = { type: T; id: ID };

/**
 * A list of cache items, including a LIST entity cache
 */
export type CacheList<T, ID> = (
  | CacheItem<T, "LIST">
  | CacheItem<T, ID>
  | DefaultTags
)[];

/**
 * Inner function returned by `providesList` to be passed to the `provides` property of a query
 */
type InnerProvidesList<T> = <
  Results extends { id: unknown }[],
  Error extends FetchBaseQueryError
>(
  results: Results | undefined,
  error: Error | undefined
) => CacheList<T, Results[number]["id"]>;

/**
 * HOF to create an entity cache to provide a LIST,
 * depending on the results being in a common format.
 *
 * Will not provide individual items without a result.
 *
 * @example
 * ```ts
 * const results = [
 *   { id: 1, message: 'foo' },
 *   { id: 2, message: 'bar' }
 * ]
 * providesList('Todo')(results)
 * // [
 * //   { type: 'Todo', id: 'List'},
 * //   { type: 'Todo', id: 1 },
 * //   { type: 'Todo', id: 2 },
 * // ]
 * ```
 */
export const providesList = <T extends string>(
  type: T
): InnerProvidesList<T> => (results, error) => {
  // is result available?
  if (results) {
    // successful query
    return [
      { type, id: "LIST" },
      ...results.map(({ id }) => ({ type, id } as const))
    ];
  }
  // Received an error, include an error cache item to the cache list
  return concatErrorCache([{ type, id: "LIST" }], error);
};

/**
 * HOF to create an entity cache to invalidate a LIST.
 *
 * Invalidates regardless of result.
 *
 * @example
 * ```ts
 * invalidatesList('Todo')()
 * // [{ type: 'Todo', id: 'List' }]
 * ```
 */
export const invalidatesList = <T extends string>(type: T) => (): readonly [
  CacheItem<T, "LIST">
] => [{ type, id: "LIST" }] as const;


type InnerProvidesNestedList<T> = <
  Results extends { data: { id: unknown }[] },
  Error extends FetchBaseQueryError
>(
  results: Results | undefined,
  error: Error | undefined
) => CacheList<T, Results["data"][number]["id"]>;

/**
 * Similar to `providesList`, but for data located at a nested property,
 * e.g. `results.data` in a paginated response.
 * The property is hard coded, so re-create a version of this function based
 * on a data shape your API returns for best results.
 */
export const providesNestedList = <T extends string>(
  type: T
): InnerProvidesNestedList<T> => (results, error) => {
  // is result available?
  if (results) {
    // successful query
    return [
      { type, id: "LIST" },
      ...results.data.map(({ id }) => ({ type, id } as const))
    ];
  }
  // Received an error, include an error cache item to the cache list
  return concatErrorCache([{ type, id: "LIST" }], error);
};


/**
 * HOF to create an entity cache for a single item using the query argument as the ID.
 *
 * @example
 * ```ts
 * cacheByIdArg('Todo')({ id: 5, message: 'walk the fish' }, undefined, 5)
 * // returns:
 * // [{ type: 'Todo', id: 5 }]
 * ```
 */
export const cacheByIdArg = <T extends string>(type: T) => <
  ID,
  Result = undefined,
  Error = undefined
>(
  result: Result,
  error: Error,
  id: ID
): readonly [CacheItem<T, ID>] => [{ type, id }] as const;

/**
 * HOF to create an entity cache for a single item using the id property from the query argument as the ID.
 *
 * @example
 * ```ts
 * cacheByIdArgProperty('Todo')(undefined, { id: 5, message: 'sweep up' })
 * // returns:
 * // [{ type: 'Todo', id: 5 }]
 * ```
 */
export const cacheByIdArgProperty = <T extends string>(type: T) => <
  Arg extends { id: unknown },
  Result = undefined,
  Error = undefined
>(
  result: Result,
  error: Error,
  arg: Arg
): readonly [CacheItem<T, Arg["id"]>] | [] => [{ type, id: arg.id }] as const;

/**
 * HOF to invalidate the 'UNAUTHORIZED' type cache item.
 */
export const invalidatesUnauthorized = () => <
  Arg = undefined,
  Result = undefined,
  Error = undefined
>(
  result: Result,
  error: Error,
  arg: Arg
): ["UNAUTHORIZED"] => ["UNAUTHORIZED"];

/**
 * HOF to invalidate the 'UNKNOWN_ERROR' type cache item.
 */
export const invalidatesUnknownErrors = () => <
  Arg = undefined,
  Result = undefined,
  Error = undefined
>(
  result: Result,
  error: Error,
  arg: Arg
): ["UNKNOWN_ERROR"] => ["UNKNOWN_ERROR"];

/**
 * Utility helpers for common provides/invalidates scenarios
 */
export const cacher = {
  defaultTags,
  providesList,
  invalidatesList,
  providesNestedList,
  cacheByIdArg,
  cacheByIdArgProperty,
  invalidatesUnauthorized,
  invalidatesUnknownErrors
};

Thank you @hrafnkellbaldurs, it has worked.

Now, the cacher utility is available for the server responses having the actual records/list in a "dynamic key" rather than hard-coded "data" key.

My recommendation to other developers is to keep the function providesNestedList and the type InnerProvidesNestedList as it is and to add the new function asprovidesNestedDynamicList and the new type as InnerProvidesNestedDynamicList which @hrafnkellbaldurs has provided in order to have flexibility.

Thanks again.