I want to do something like this:

document("post").insert({ ... } /* TYPE SHOULD BE AUTOMATICALLY DETERMINED BY TYPESCRIPT */ ); 

The document() function returns an object containing functions such as insert, the object also contains a document property which is assigned the value of the argument passed to document() function. The object has a type of DocumentObject and functions like insert can access document propery using this.document. Everything is working fine but I want insert to accept an argument of a certain type determined by the value of this.document.

How can I have parameters that have types that vary based on the value of another variable. This is the declaration of insert:

export default async function (this: DocumentObject, record: ???): Promise<...> {...}

The variable this.document (which can be accessed from the function body) can contain the following values: post, user, comment. I also have respective types for each possible value: Post, User, Comment. This is howthis.document is defined:

document: "post" | "comment" | "user" = ...;

My Question Is: How can I use Typescript to map each value to its respective type, so I can assign that type to record parameter? Is this even possible in Typescript?

Note: Not a duplicate of Conditional parameter type based on another parameters’ value, and Conditional type based on the value of another key; They suggested I use function overloads, is there another way to do that?