Sharing functionality

⚠️ Available starting with v10.3.0

Often, multiple documents have a shared shape, and it’s convenient to share functionality across them. For example, you might want a function that renames a user or a profile. For that purpose, Typesaurus provides a set of types and methods that enable sharing of functionality across the refs and docs in a type-safe way.

export interface NameFields {
  firstName: string;
  lastName: string;
}

function rename(entity: Typesaurus.SharedEntity<NameFields>, name: string) {
  const [firstName = "", lastName = ""] = name.split(" ");
  return entity.update({ firstName, lastName });
}

rename(user.as<NameFields>());

In this example, the as method checks that the user extends NameField. It would resolve unknown if the user model weren’t compatible with NameFields, triggering a type error:

rename(post.as<NameFields>());
// Argument of type 'unknown' is not assignable to parameter of type 'SharedEntity<NameFields>'.ts(2345)

On the function side, we use Typesaurus.SharedEntity type that unions Typesaurus.SharedRef and Typesaurus.SharedDoc. These shared types narrow the data type to the given shape (i.e. NameFields) and limit the available methods to the ones that don’t depend on the full type of the model. The set, upset, and as methods are stripped to prevent data inconsistencies.

→ Read more about the as method

→ Read the architecture decision record (ADR-2)