enchanceEndpoints -> transformResponse TS error

[bogdan0083]

Hello guys! I'm trying to enhance the generated api and add transformResponse function to have normalized response:

import type {EntityState} from '@reduxjs/toolkit';
import {createEntityAdapter} from '@reduxjs/toolkit';
import type {
  GetTodosApiResponse,
  Todo as GeneratedTodo,
  TodosGetApiResponse,
} from '@shared/api/generatedApi';
import {generatedApi} from '@shared/api/generatedApi';

const todosAdapter = createEntityAdapter<Todo>();
const initialState = todosAdapter.getInitialState();

export type Todo = GeneratedTodo;

export const todosApiSlice = generatedApi.enhanceEndpoints<string>({
  addTagTypes: ['Todos'],
  endpoints: {
    getTodos: {
      // This property shows TypeScript error:
      // TS2322: Type '(response: Todo[]) => EntityState ' is not assignable to type 'undefined'.
      transformResponse(response: Todo[]): EntityState<Todo> {
        return todosAdapter.setAll(initialState, response);
      },
  },
});

The code works. The response get transformed but for some reason the ts compiler is not happy. Is there a way to fix ts error?

Thanks!

[phryneas]

export const todosApiSlice = generatedApi.enhanceEndpoints<string>({

you should definitely not be putting that <string> there.

Apart from that, unfortunately currently enhanceEndpoints cannot change the type of the returned value. It will work in runtime code, but they types will not accept it.
I'll see if I can change that somehow soon.

[bogdan0083]

you should definitely not be putting that there.

Yeah, that was not necessary.

I'll see if I can change that somehow soon.

Thank you! That would help to use transformed data types. Right now it's impossible to use selectFromResult as well:

  const {data, error, isLoading} = useGetTodosQuery({_page: page}, {
    selectFromResult: (result) => ({
      ...result,
      // doesn't know about 'entities' property, obviously :)
      data: result.data ? Object.values(result.data.entities) : emptyArr,
    }),
  });

But that will be fixed automatically when we will have the ability to change the type of the returned value I guess.

[phryneas]

You can watch this in #2730