Define interface as a combination of some predefined key (id: string) and key-access types ({ [key:string]: AnotherInterface })

Question

I have a specific use case where my database record has following data

{
  id: 'user_id_1',
  '26-08-23': [{...other object}],
  '27-08-23': [{...another object}]
  ...
}

I would like to know how I can create a typescript interface to support the above case. The basic idea was to have two interfaces and see if I could extend but that doesn't work

export interface DateMappedObject {
  [date: string]: UserAttendanceDateMap
}

export interface UserAttendance extends DateMappedObject {
  id: string;
}

Can someone suggest a solution please?

---

Tldr;

Why the object is shaped this way?

• I'm using Firebase/firestore and I'm achieving two benefits with the above object The above approach allows me to get all of that data in one query
• The data is limited for each month, so the scalability issue is not a concern here)
• I'll use the dates to populate a calendar with data for a day and date-key allows quick access by index-key pattern.