However, we were previously adding the read/unread fields on the client side in our notificationsSlice reducer when we received the entries, and now the notification entries are being kept in the RTK Query cache. For the getPost example, we could have transformResponse: (responseData) => responseData.post, and it would cache just the actual Post object instead of the entire body of the response. That way, we can still have a single API slice with a single middleware and cache reducer, but we can move the definition of some endpoints to other files. If Component A calls useGetPostQuery (42), that data will be fetched. Now, if we click several times on a reaction button quickly, we should see the number increment in the UI each time. Our selectUserById selector currently has to loop over the cached array of users to find the right User object. The entire component was grayed out, because we just refetched the entire list of posts in response to that one post being updated. Let's add a new addReaction mutation and use that to update the corresponding Post on the server every time the user clicks a reaction button. Here's my api definition. The example has some intentionally wonky behavior when editing the name of a post, there is a decent chance you'll get a random error. The top one will only update after a successful mutation and resync with the server. You should see a GET request to /posts as we fetch the initial data. RTK. Normally you should stick with using the hooks, but here we're going to work with the user data using just the RTK Query core API so you can see how to use it. This can be useful if you wish to determine whether the mutation succeeds/fails inline at the call-site. In , we trigger the initial notifications fetch with useGetNotificationsQuery(), and switch to reading the metadata objects from state.notificationsSlice. We've now seen three different ways that we can manage transforming responses: Each of these approaches can be useful in different situations. There are several ways to handle authentication with RTK Query. When the cache entry is removed, we clean up the Websocket subscription. Mutation endpoints may also modify the response contents before the result is cached, define "tags" to identify cache invalidation, and provide cache entry lifecycle callbacks to run additional logic as cache entries are added and removed. As we've seen, RTK Query includes some powerful options for controlling how we manage cached data. // Triggering `updatePostOne` will affect the result in this component, // but not the result in `ComponentTwo`, and vice-versa. We can use the same useGetPostQuery hook that we used in to read the Post entry from the cache in the store, and we'll use the new useEditPostMutation hook to handle saving the changes. The query callback may also return an object containing the URL, the HTTP method to use and a request body. As we go through, we'll see how to use all the major features of RTK Query, as well as how to migrate existing uses of createAsyncThunk and createSlice over to use the RTK Query APIs. In this case, we'll call the field postsForUser, and we can destructure that new field from the hook result. In the example from https://redux-toolkit.js.org/rtk-query/usage/examples#using-extrareducers a extraReducer in autSlice.ts that is called when the login mutation in services/auth.js is intially called with credentials of Type LoginRequest as its action.payload. Our similarly switches over to reading the cached data and metadata. RTK Query immediately started a "remove this post data" timer. Check out the PostDetail component for an example of Class Component usage. Both mutations make their networks calls and changes are reflected in the server. We'll export the useGetUsersQuery hook just for consistency, but for now we're not going to use it. Thanks for reading through this tutorial, and we hope you enjoy building applications with Redux! Time to get to the crux of this tutorial, which is learning how to use React - Query in a project to fetch and mutate data from an API. It's important to understand that RTK Query uses a "document cache" approach, not a "normalized cache". What happens if we want to code-split some of our endpoint definitions, or move them into another file to keep the API slice file from getting too big? javascript. /* Temporarily ignore adapter - we'll use this again shortly, const usersAdapter = createEntityAdapter(), const initialState = usersAdapter.getInitialState(), // Calling `someEndpoint.select(someArg)` generates a new selector that will return. The query hook will do a "shallow" comparison on this returned object, and only re-render the component if one of the fields has changed. But, the component mounted right away and subscribed to the same Post data with the same cache key. The UI switches over to show , but this time there's no network request for the individual post. You should now have a solid understanding of what Redux Toolkit and React-Redux are, how to write and organize Redux logic, Redux data flow and usage with React, and how to use APIs like configureStore and createSlice. When the number of subscribers goes to 0 and the cache lifetime timer expires, the cache entry will be removed, and cacheEntryRemoved will resolve. We were previously using createEntityAdapter in usersSlice to manage normalized users data. Let' see what notificationsSlice looks like after we add this logic. In short: More information about these can be found here. // the query result object for a query with those parameters. The query hooks also give us the ability to select pieces of the cached state by providing a selectFromResult option, and only re-render when the selected pieces change. Now click "Edit Post" inside the single post page. Recently I started using RTK Query and I have a problem with selecting data from the store after mutation. I trigger mutation in the first component and I need to get results in the second component. So far, all of our query endpoints have simply stored the response data from the server exactly as it was received in the body. You may have heard the term "normalized cache" in relation to other data fetching libraries like Apollo. This should be a unique string shared between each In case the request fails, we can await queryFulfilled, catch a failure, and undo the patch changes to revert the optimistic update. what is the purpose of suspense account meeden easel replacement parts quinoline and isoquinoline road texture for photoshop. The first item in the tuple is the "trigger" function and the second element contains an object with status, error, and data. Event Loop + V8 Engine + libuv threadpool. If we really want to just refetch the list of posts for the getPost endpoint, you can include an additional tag with an arbitrary ID, like {type: 'Post', id: 'LIST'}, and invalidate that tag instead. Here's some suggestions for when you should consider using them: We've completed updating our posts and users data, so all that's left is working with reactions and notifications. Compared to popular alternatives like React-Query, the main strength of RTK Query is its default integration with the redux store. We've added a transformResponse option to the getUsers endpoint. If we call patchResult.undo(), it automatically dispatches an action that reverses the patch diff changes. We can integrate createEntityAdapter into our extendedApiSlice, and actually use createEntityAdapter to transform the data before it's cached. Its most helpful when dealing with resources that have both query endpoints and mutation endpoints (e.g. Clicking the "Refresh" button now triggers the mock Websocket server to push out another set of notifications. Copyright 20152022 Dan Abramov and the Redux documentation authors. Calling the "mutation trigger" returns a promise with an unwrap property, which can be called to unwrap the mutation call and provide the raw response/error. RTK Query allows multiple components to subscribe to the same data, and will ensure that each unique set of data is only fetched once. In this app, the notifications cache entry will never be removed because we never unsubscribe from the data, but it's important to see how the cleanup would work for a real app. With those changes in place, we can update our UI components to fetch and display notifications. Endpoints can define a transformResponse handler that can extract or modify the data received from the server before it's cached. When the number of active subscriptions goes down to 0, RTK Query starts an internal timer. The is still using the cached Post entry that was fetched earlier. In this case, our getUsers endpoint doesn't need any parameters - we always fetch the entire list of users. You should also see how RTK Query can simplify the process of fetching and using cached data. There is one caveat here. Since this example app is small, we'll just give the name of the reaction, and let the server increment the counter for that reaction type on this post. const [getUser, { isLoading: isUserLoading }] = useGetUserQuery (resultFromLoginMutation); And I don't know how to do that. In a fully normalized de-duplicating cache, only a single copy of this Todo object would be stored. Mutation endpoints are defined by returning an object inside the endpoints section of createApi, and defining the fields using the build.mutation() method. In this scenario, a post is fetched with useQuery, and then an EditablePostName component is rendered that allows us to edit the name of the post. The "mutation trigger" is a function that when called, will fire off the mutation request for that endpoint. Normally, selectors expect the entire Redux state as their first argument, and extract or derive a value from state. These specific tags look like {type: 'Post', id: 123}. If you need to pass in multiple parameters, pass them formatted as a single "options object". In a real app, this could be any kind of external subscription or polling connection you need to receive ongoing updates. You can look at the examples from this repository. Copyright 20152022 Dan Abramov and the Redux documentation authors. Since result is being kept in the Redux store, we can't mutate it - we need to return a new object. Endpoints can define an onQueryStarted function that will be called when a request starts, and we can run additional logic in that handler. RTK Query is responsible for: Fetching data and keeping cached data on the client-side. If we reload the page, all of our user-related display is broken because the state.users slice has no data. Internally, RTK Query keeps a reference counter of active "subscriptions" to each endpoint + cache key combination. We can use selectFromResult to have read just a filtered list of posts from the cache. // Example: `updatePost().unwrap().then(fulfilled => console.log(fulfilled)).catch(rejected => console.error(rejected)), // Execute the trigger with the `id` and updated `name`, // Or from '@reduxjs/toolkit/query' if not using the auto-generated hooks. We can do that same process using RTK Query. For a small update like adding a reaction, we probably don't need to re-fetch the entire list of posts. That depends on knowing the most recent notification timestamp, so we add a thunk we can dispatch that reads the latest timestamp from the cache state and tells the mock server to generate newer notifications. Once we call a mutation endpoint that is defined to invalidate this tag, all of the query endpoints that have this tag will automatically refetch and update the cache (the store). So, we can create a cache selector with no argument, and the cache key becomes undefined. The first is the cache key arg that was passed when the request started. This should be a unique string shared between each mutation hook instance you wish to share results. If we inspect the API slice object, it includes an endpoints field, with one endpoint object inside for each endpoint we've defined. It takes three arguments: the name of the endpoint to update, the same cache key value used to identify the specific cached data, and a callback that updates the cached data. // Include a field called `postsForUser` in the hook result object, // which will be a filtered list of posts, // In a real app, we'd probably need to base this on user ID somehow, // so that a user can't do the same reaction more than once. This is an example of a CRUD service for Posts. In the example below you'll notice a few things. These examples are not meant to be what you base your application on, but exist to show very specific behaviors that you may not actually want or need in your application. Hot reloading, CSB service workers and msw sometimes have trouble getting on the right page -- when that happens, just refresh in the CSB browser pane. // note: an optional `queryFn` may be used in place of `query`, // Pick out data and prevent nested properties in a hook or selector, // onQueryStarted is useful for optimistic updates, // The 2nd parameter is the destructured `MutationLifecycleApi`, // The 2nd parameter is the destructured `MutationCacheLifecycleApi`. There has to be one API slice per app for RTKQ to work best. It's common for apps to make an initial request to fetch data from the server, and then open up a Websocket connection to receive additional updates over time.
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