I have a specific object with the following structure:
{
first: (state: S, payload: boolean) => { payload: boolean, type: string },
second: (state: S) => { payload: undefined, type: string },
}
My goal is to manipulate this object by removing the state property. This modification results in the following shape:
{
first: (payload: boolean) => { payload: boolean, type: string },
second: () => { payload: undefined, type: string },
}
The output object is defined as follows:
{ [K in keyof T]: { (payload: Parameters<T[K]>[1]): { payload: Parameters<T[K]>[1]; type: K; }; name: K; } }
In this context, Parameters<T[K]>[1] can potentially hold the value undefined, such as in the case of second().
Although the implementation is mostly successful and correctly infers function names, parameters, and return types, an issue arises when dealing with scenarios where payload may be undefined. For instance:
first(true); // executes without errors
first('true'); // results in failure due to type mismatch
second(undefined) // no issues are encountered
second(); // triggers an error
The corresponding error message reads as:
(property) second: (payload: undefined) => {
payload: undefined;
type: "second";
}
Expected 1 arguments, but got 0. [ts(2554)]
Hence, the main question revolves around how to make the parameter optional only when no payload is provided. Adding
(payload?: Parameters<T[K]>[1])(payload: Parameters<T[K]>[1] | undefined)