Setting the User type

In order to use your own type for req.session.user (default is unknown) you can make use of declaration merging.

1. Create the typings folder

Create a folder named typings inside your src folder (or an equivalent folder).

2. Extend Gatekeeper's User Interface

Inside the typings folder create another folder called gatekeeper-authentication. Inside it create a file named index.d.ts. Inside this file you will extend Gatekeeper's User type, like this:

interface CustomUser {
    id: number;
    username: string;
    // ...
}

declare module 'gatekeeper-authentication' {
    export interface User extends CustomUser {}
}

3. Include the typings folder inside your tsconfig.json

Finally, inside your tsconfig.json file, include the route to your typings folder inside the array of the property typeRoots, like this:

{
    // ...
    "typeRoots": ["./src/typings"]
    // ...
}

Now, if you check the type of req.session.user, you'll see it is now the type you defined!