TypeScript: Describe Object of Objects

Question

Say I have an interface like this:

interface Student {
  firstName: string;
  lastName: string;
  year: number;
  id: number;
}

If I wanted to pass around an array of these objects I could simply write the type as Student[].

Instead of an array, I'm using an object where student ids are keys and students are values, for easy look-ups.

let student1: Student;
let student2: Student;
let students = {001: student1, 002: student2 }

Is there any way to describe this data structure as the type I am passing into or returning from functions?

I can define an interface like this:

interface StudentRecord {
  id: number;
  student: Student
}

But that still isn't the type I want. I need to indicate I have an object full of objects that look like this, the same way Student[] indicates I have an array full of objects that look like this.

Answer 1

you can simply make the key dynamic:

interface IStudentRecord {
   [key: string]: Student
}

Answer 2

Use the built-in Record type:

type StudentsById = Record<Student['id'], Student>;