feat: Add optimistic updates

[ntucker]

Closes #191, closes #179.

Motivation

Make sites faster.

Solution

class ArticleResource extends Resource {
  static partialUpdateShape<T extends typeof Resource>(
    this: T,
  ): MutateShape<
    SchemaDetail<Readonly<AbstractInstanceType<T>>>,
    Readonly<object>,
    Partial<AbstractInstanceType<T>>
  > {
    return {
      ...super.partialUpdateShape(),
      options: {
        ...this.getFetchOptions(),
        optimisticUpdate: (params: any, body: any) => ({
          id: params.id,
          ...body,
        }),
      },
    };
  }
  static createShape<T extends typeof Resource>(this: T) {
    return {
      ...super.createShape(),
      options: {
        ...this.getFetchOptions(),
        optimisticUpdate: (
          params: Readonly<object>,
          body: Readonly<object | string> | void,
        ) => body,
      },
    };
  }
}

const appendUpdater = (
  newArticleID: string,
  articleIDs: string[] | undefined,
) => [...(articleIDs || []), newArticleID];

Partial updates

const update = useFetcher(ArticleResource.partialUpdateShape());

update({ id: '5' }, { isStaff: true });

Optimistic create with eager updates

This lets you eagerly insert into a list.

You'll need to make a fake id that won't collide so it can put it in the cache somewhere.

const create = useFetcher(ArticleResource.createShape());

create({}, { id: 'made up temp id', content: 'fun times' }, [
  [ArticleResource.listShape(), {}, appendUpdater],
]);

Race conditions

Since optimistic updates are applied after all realized updates, all optimistic updates with a date equal to or before the currently realizing update should be removed. Note: this still potentially creates a problem when multiple endpoints interact on the same entity, but there is no clear way to realize that solution and this problem is far less likely. Mostly the expected issue is toggling a single control over quickly.

Update NetworkManager detection mechanism

Since we're now passing fetch actions through to the reducer to handle, we need a new mechanism to detect if NetworkManager isn't setup. This is a common error for those attempting to use redux.

We will add a flag to the meta named nm that is set to true when the action passes through NetworkManager.