rtk-query-api

Development

RTK Query createApi best practices

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RTK Query - createApi

Structure

One API slice per base URL / data source
Define API slices in state-manager/api.ts files
Export generated hooks alongside the API

// ✅ GOOD - state-manager/api.ts
import { createApi, fetchBaseQuery } from "@reduxjs/toolkit/query/react";
import { EntityTags } from "./types";

export const myApi = createApi({
  reducerPath: "myApi",
  baseQuery: fetchBaseQuery({ baseUrl: "/api" }),
  tagTypes: [EntityTags.Entity, EntityTags.Entities],
  endpoints: (build) => ({
    getEntity: build.query<Entity, string>({
      query: (id) => `entities/${id}`,
      providesTags: [EntityTags.Entity],
    }),
  }),
});

export const { useGetEntityQuery } = myApi;

Define tags as enums in state-manager/types.ts:

export enum EntityTags {
  Entity = "Entity",
  Entities = "Entities",
}

Endpoints

Use build.query for GET requests
Use build.mutation for POST/PUT/DELETE
Type both response and argument: build.query<ResponseType, ArgType>
Use void for no arguments: build.query<Data[], void>

Caching & Tags

Define tags as enums in types.ts
Use providesTags on queries for cache invalidation
Use invalidatesTags on mutations to trigger refetch
Use keepUnusedDataFor for custom cache duration

endpoints: (build) => ({
  getItems: build.query<Item[], void>({
    query: () => "items",
    providesTags: [ItemTags.Items],
    keepUnusedDataFor: 60, // seconds
  }),
  addItem: build.mutation<Item, Partial<Item>>({
    query: (body) => ({ url: "items", method: "POST", body }),
    invalidatesTags: [ItemTags.Items],
  }),
}),

Transform Responses

Use transformResponse to reshape API data
Use transformErrorResponse for custom error handling

getItems: build.query<Item[], void>({
  query: () => "items",
  transformResponse: (response: ApiResponse) => response.data.items,
}),

Error Handling

Always catch errors in custom baseQuery or queryFn
Return { data } on success, { error } on failure

// ✅ GOOD - errors are caught and returned
queryFn: async (arg) => {
  try {
    const data = await fetchData(arg);
    return { data };
  } catch (error) {
    return { error: { status: "CUSTOM_ERROR", data: error } };
  }
},

Registration

const APIs = {
  [myApi.reducerPath]: myApi,
};