Help - How to create select for RTKQ endpoint with arguments?

[nouman91]

Hi,
I have a use case where I want to create a selector for the RTKQ endpoint. The idea is to have an error selector for the endpoints and use that in the components.
I have looked everywhere so far I have not found any example of how to create a selector with arguments.
Example code:

export const myApi = apiSlice.injectEndpoints({
  endpoints: (builder) => ({
    getSomeData: builder.query<Type[], string[]>({
      query: (params) => ({
        params: { uuids: params.join(',') },
        url: 'url,
      }),
      transformResponse: (res: { results: Type[] }) => res.results,
          }),
  }),
});


const apiInfo = apiSlice.endpoints.getThreats.select(???? how to pass argument here)
export const apiErrorSelector = createSelector(apiInfo, state=>state.error);

[EskiMojo14]

the typical pattern is to make a new selector each time:

export const apiErrorSelector = createSelector(
  (state, arg) => apiSlice.endpoints.getThreats.select(arg)(state), 
  state=>state.error
);

apiErrorSelector(state, arg)

this however will suffer from incorrect memoisation. on the other hand, you could wrap your own selector creator:

const makeApiErrorSelector = (arg) => {
  const selectApiInfo = apiSlice.endpoints.getThreats.select(arg)
  return createSelector(selectApiInfo, state=>state.error);
}

This would allow for proper memoisation as long as you hold onto the selector instance.

To offer a completely different approach, have you considered using selectFromResult?

[phryneas]

Also, with some memoization:

const createApiSelector = createSelector(
  arg => arg,
  apiSlice.endpoints.getThreats.select
>

export const apiErrorSelector = createSelector(
  state => state,
  (state, arg) => createApiSelector(arg), 
  (state, selector) =>selector(state).error
);

[nouman91]

Thank you! While these solutions work, I will go with a different approach as my idea was to show errors without much for business logic since this will require to know arguments it will not work for my use cases.

[andreisocaciu]

I think this solution should be included in the documentation. I searched a bit to find a solution, and I really think it would be easier if it was included in the section about using RTK Query without hooks. Right now it only talks about simple queries that don't have any parameters.

[EskiMojo14]

yeah, in general that section is a little neglected - I'll see if I can add a bit to it today

[EskiMojo14]

@andreisocaciu thoughts on #3963?

[andreisocaciu]

@EskiMojo14 That is perfect.