Skip to main content

Viewer

Viewer represents who's viewing the content in your product or app. Every time data is loaded or changed, the Viewer is required to determine if that action can be performed.

Viewer is just an interface that can easily be implemented by any object and is not tied to any implementation or authentication mechanism.

Here's what the Viewer interface looks like:

export interface Viewer<
  TEnt extends any = Ent<any> | null,
  TID extends any = ID | null,
> {
  viewerID: TID;
  viewer: () => Promise<TEnt>;
  instanceKey: () => string;
  context?: Context<any>;
}

viewerID​

The viewerID indicates a unique identifier, usually the id in the database of the User or Account that's associated with whoever's logged in.

viewer​

The viewer method returns the Ent associated with the logged in user or null if there's no logged in viewer.

instanceKey​

The instanceKey returns a unique identifier associated with this Viewer. It may be used to perform caching to save requests to the database.

context​

The context returns the Context associated with the "request".

LoggedOutViewer​

The framework comes with a simple Viewer to represent the logged out viewer. It's the default Viewer used if none is provided. It can be instantiated as follows:

const vc1 = new LoggedOutViewer();
const vc2 = new LoggedOutViewer(context);

IDViewer​

There's also a simple IDViewer which takes the viewerID and can be used for simple projects. It can be instantiated as follows:

const vc1 = new IDViewer(id);
// both context and ent are optional below:
// if provided, context satisfies the `context` requirement in the Viewer interface
// if provided, ent satisfies the `viewer` requirement in the Viewer interface
const vc2 = new IDViewer(id, {context: context, ent: user});
const vc3 = new IDViewer({viewerID: id, context: context, ent: user});

It exists as an example of what a simple implementation of Viewer looks like. It probably doesn't suffice for complex applications so feel free to implement Viewer that works for your use-case.