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Version: 6.5

useCache()

function useCache(
endpoint: ReadEndpoint,
...args: Parameters<typeof endpoint> | [null]
): Denormalize<typeof endpoint.schema> | null;

Excellent to use data in the normalized cache without fetching.

  • On Error (404, 500, etc):
    • Returns previously cached if exists
    • null otherwise
  • While loading:
    • Returns previously cached if exists
    • null otherwise

Example

Using a type guard to deal with null

function Post({ id }: { id: number }) {
const post = useCache(PostResource.get, { id });
// post as PostResource | null
if (!post) return null;
// post as PostResource (typeguarded)
// ...render stuff here
}

Paginated data

When entities are stored in nested structures, that structure will remain.

export class PaginatedPost extends Entity {
readonly id: number | null = null;
readonly title: string = '';
readonly content: string = '';

pk() {
return this.id;
}
}

export const getPosts = new RestEndpoint({
path: '/post\\?page=:page',
schema: { results: [PaginatedPost], nextPage: '', lastPage: '' },
});
function ArticleList({ page }: { page: string }) {
const { results: posts, nextPage, lastPage } = useCache(getPosts, { page });
// posts as PaginatedPost[] | null
if (!posts) return null;
// posts as PaginatedPost[] (typeguarded)
// ...render stuff here
}
Conditional Dependencies

Use null as the second argument on any rest hooks to indicate "do nothing."

// todo could be undefined if id is undefined
const todo = useCache(getTodo, id ? { id } : null);

Useful Endpoints to send

Resource provides these built-in:

Feel free to add your own RestEndpoint as well.

Query arbitrary Entities

Query provides programmatic access to the Rest Hooks store.

Fixtures
GET /users
[{"id":"123","name":"Jim"},{"id":"456","name":"Jane"},{"id":"777","name":"Albatras","isAdmin":true}]
api/User.ts
export class User extends Entity {
id = '';
name = '';
isAdmin = false;
pk() {
return this.id;
}
}
export const UserResource = createResource({
path: '/users/:id',
schema: User,
});
UsersPage.tsx
import { Query, schema } from '@rest-hooks/rest';
import { UserResource, User } from './api/User';
const sortedUsers = new Query(
new schema.All(User),
(entries, { asc } = { asc: false }) => {
const sorted = [...entries].sort((a, b) => a.name.localeCompare(b.name));
if (asc) return sorted;
return sorted.reverse();
}
);
function UsersPage() {
useFetch(UserResource.getList);
const users = useCache(sortedUsers, { asc: true });
if (!users) return <div>No users in cache yet</div>;
return (
<div>
{users.map(user => (
<div key={user.pk()}>{user.name}</div>
))}
</div>
);
}
render(<UsersPage />);
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