Now our users will be stored in data and the component will re-render as soon as data is fetched or an error occurs. What we will do is: we will extract the data fetching logic to a custom hook and use that hook in the Posts component. We can do that in useEffect, as above: This custom Hook must return states we defined. Now we return the states that are created inside the hook as an object. The difference between React hook and a React component is that hook doesn't return JSX. The components basics will look like this: Were going to save data in state users which is handled by useState Hook. I've started developing "useFetch" as a tutorial to build a custom hook. Show loading screen. When we dont have an initial state, we default to 0. Yes, of course. For simple stuff like fetch, the "new" approach makes it harder to read: We should try to avoid using stuff just because is "new" and being like this And instead use the new features where they are useful. Example: useFetch. The whole code block for getting the data is called as soon as its defined (lines 6 and 18). The componentDidUpdate lifecycle method, on the other hand, gets invoked when theres a change in the component. We will use the JSONPlaceholder service to fetch fake data. We also went through cleaning up our useEffect hook which helps prevent a good number of problems in our app. We can somewhat address these problems in a slightly better way. Are you sure you want to hide this comment? Now, our useFetch hook is generic and we can use it as we want in our various components. We will leverage both useState and useEffect hooks for our custom fetch hook. This is where we pass in the URL to fetch data from. For example, we can create a refetch() function inside the hooks that re-fetches the API when called. data fetching. One of the main advantages of using React hooks is the re-usability of logic. It also makes the code more readable, efficient, and easy to maintain. Memoization is a technique we would use to make sure that we dont hit the hackernews endpoint if we have made some kind of request to fetch it at some initial phase. This function should actually do the data fetching and return a promise which resolves with the data, or rejects with an error on failure. But see how we need to manage three separate state variables? Step 1 Let's create a new file: useFetch.js In app.js we are importing our useFetch hook and utilizing it like any other Hook. Note that it's not possible to get all the objects in a single query so first fetching all and filtering an array with the id is not an option Lets create our file to write our custom fetch hook, to start we need to create our useFetch.ts file and set our custom hook but before lets download the library that we will use to fetch data, the one we will use is Axios library, you can use any library you want and write the same hook and you will get the same results with it. On line four we first check whether the component is mounted. Bringing types to JS. Polling is one way to do this; hitting an endpoint over and over at some set interval to check for fresh data to display in the UI. After that, Id recommend reading Shedrack Akintayos Getting Started With React Hooks API. . The received data is saved (cached) in the application via useRef, but you can use LocalStorage (see useLocalStorage ()) or a caching solution to persist the data. If you fetch data in several components inside the project, youre also breaking the DRY (Dont Repeat Yourself) principle . Declaring cache in a different scope works but it makes our hook go against the principle of a pure function. In the idle state, we could let users know that they could make use of the search box to get started. They let you use state and other React features without writing a class. We usually need this repetitively at various places in website. Implementing Maths in Javascript: Set theory, Relearning JavaScript String, Number, and Array. While this tutorial will cover the Hacker News Search API, well have the hook work in a way that it will return response from any valid API link we pass to it. The normal code for fetching the data from the server and updating in the component is shown below. This function can be returned from the hook and can be called from the component. Creating A Custom Hook "A custom hook is a JavaScript function whose name starts with 'use' and that may call other Hooks." React Docs In this video we will build a powerful Custom React Hook useFetch () that will help us to fetch the data from server along with that it will provide us different API request states like. How To Create a React Native First Application & Explanation of the code step by step. How to Fetch Data in React With A Custom useFetch Hook 31,511 views Aug 23, 2021 In this video I will show how to make a custom useFetch hook in react. For demonstration purposes, Ill use the fake API JSONplaceholder. Inside the component, import the useFetch hook from its javascript file. More after jump! Thanks for keeping DEV Community safe. When the request returns we need to set loading to false, and depending on whether it was successful or not, set the data or the error. Using React, you can create a custom hook to fetch data from an API. 3. Why React Hooks are used One of the main advantages of using React hooks is the re-usability . E.g. Yup, but ideally that should be in the consumer side of the hook, not in its internals. We can write the code in a separate js file and call it with URL from all the components that might need to fetch the data from the server. Building your own Hooks lets you extract component logic into reusable functions. Besides, we also want to make sure that React helps in cleaning up our mess when we no longer want to make use of the component. Another cool thing with state machines is that we can specify which states the machine can transition to from certain states, and what actions should run in between. Custom Hooks start with "use". Software Engineer, Anime, Rockstar, Fitness and Game Enthusiast. code of conduct because it is harassing, offensive or spammy. Other components and custom hooks consume wrapper and it delegates calls into your hook. And when the state within the custom Hook updates, the component that calls the Hook also is re-rendered in order to retrieve the new data! 4. Inside the file, create a new function with the name of the hook. Suddenly you've got at least 6 state variables (unless you can find a way to reuse them?). In this case, we get back all the data, loading, and error state that we need to be able to use the same structure for our component as before, but without having to useEffect. The unique aspect about custom Hooks is that they can call other Hooks. We've created a custom hook, which accepts a function (fetchFn) as a parameter (it also accepts some other useful parameters, but they're not essential). Yup, you can configure ESLint with eslint-plugin-react-hooks to do just that, but it throws a warning mainly because you might want to just depend on some of the things inside the effect, not all of them. What is React Hooks React hooks were first introduced in React 16.8. We set its initial state to 100, so whenever we call add(), it increases count by 1, and whenever we call subtract(), it decreases count by 1. To make an API call, use a useEffect hook because it will trigger the API call function inside it when rendered. Now just like any React hook we can directly use our custom hook to fetch the data. We can do that in useEffect, as above: If not, the error message will be set to the error variable. I'm quite new to custom hooks and I'm just wondering if there is anything wrong with this approach? It only returns the state variable or function that you want to use in a component. So each time you call useContent in a new component, the effect (fetching data) is run once. Lets see how that works! Lets use the component UserList.js, where we want to fetch users after the page is mounted to the view. Once we get data from server. Well explore useRef to help us in achieving that. No data yet. Show loading screen. In the fetching state, we could show a spinner. This is a very simple app to demonstrate how to fetch JSON data from an API service like jokeapi.dev Requirements react-hooks-form react-scripts Clone Repository React hooks were first introduced in React 16.8. At the end of the API call, this loader is set back to false by using the finally block. With practical takeaways, live sessions, video recordings and a friendly Q&A. We can abstract the logic required to make this work into a custom hook. You should also check: I'm a learning man. The only dependency we're going to put in the useEffect dependency array is Url because if the Url changes, we have to request new data. Thats really what it is, and along with a JavaScript function, it allows you to reuse some piece of code in several parts of your app. A good thing to note about this is that using custom hooks and hooks inside a useEffect causes an infinite loop. Ask Question Asked 1 year, 5 months ago. There are 10 available built-in hooks, but the two most common hooks are useState and useEffect . Basic - Just fetch data with useFetch. useState: It is used to add the state in functional components. When we were learning about using the Effect Hook, we saw this component from a chat application that displays a message indicating whether a friend is . From our states declaration, we can see that if it's idle and receives the FETCH command, it should transition to loading. It takes a hit for readability when shorter than 4 as well, since formatters like prettier will inline: So yes, in the cases where you have the catch in the same place as the call, can chain 4 or more operations that are all one liners, and never need to refer to something in a prior step of the chain, it's slightly cleaner, but it's rare enough that I wouldn't fault anyone for just forgetting about the syntax altogether. Inside the file, create a new function with the name of the hook. They are functions that let you hook into React state. Magic or simple rules? Add a comment 1 Answer Sorted by: 1 Hooks are run independently in different components (and in different instances of the same component type). We need to add some modifications to our useFetch hook. It will become hidden in your post, but will still be visible via the comment's permalink. React & React Native Developer Talks About #ReactNative, #React, #NextJs #Css #Git, Eatin: A Simple Reservation System based on Play Framework. Well also notice that were killing off the effect if the URL is falsy, so it makes sure we dont proceed to fetch data that doesnt exist. The state and state update function come from the state hook called useState that is responsible to manage the local state for the data that we are going to fetch for the App component. It's just using the old Promise api Do you objectively believe that? So what we usually do when we need to fetch data is: 1. but apart from those general advantages, a custom hook implementation for fetching data also provides the benefit of having a singular, controlled way to handle requests state such as when a request has been fulfilled successfully (the data has been retrieved), the request is in loading state (have a baseline loading state visual hint - loader), How exactly you'd go about this probably depends on your app, and how you want to use it, but I'm going to show you a fairly generic way that can be used to help simplify your component. If the previous query value isnt the same as the current value, the useEffect get invoked again. You shouldn't use "one or the other", you should just use the one that makes the code easier to read. Creating A Custom Hook "A custom hook is a JavaScript function whose name starts with 'use' and that may call other Hooks." React Docs That's really what it is, and along with a JavaScript function, it allows you to reuse some piece of code in several parts of your app. For this example we're using xstate and @xstate/react so you'll need to install those as dependencies. useState According to the docs, the useState hook is similar to the this.setState () call in class components, except that it doesn't merge the old and new states together. If our hook tries to make an update while the component has unmounted because of some Promise just got resolved, React would return Can't perform a React state update on an unmounted component. The load function is our loadData function and should 'send' a command back to the machine. Consider the code example below (or check out the codepen underneath). Try redaxios instead. To learn more, check out the JavaScript Fetch API section. To ensure youre following along, there is also an article written by Adeneye David Abiodun that covers best practices with React Hooks which Im sure will prove to be useful to you. To prevent from fetching data on unmounted component, we can use another Hook, useRef. Given a URL, this hook will return an object containing the data and an optional error message. What we did here was to import our custom hook from the file we declared it in, so we could make use of it in our app. The difference between React hook and a React component is that hook doesn't return JSX. Reactjs , DevOps passionate with extensive Start-up experience. Currently a PhD student at University of Bristol, PhD Candidate in Digital Health and Care at University of Bristol, BSc Software Engineering, Mustafa from Afghanistan 23 years old a web developer, // if aFunction changes, useExample will not react to that, // Your hook will always work as expected, Set your Web App to Dark/Light Mode based on User System Settings. For every application to work dynamically, it fetches the data from the server and then displays it in the user interface. Everything TypeScript, with code walkthroughs and examples. So, before we attempt to make state changes, we first confirm if the component has been unmounted. React wait for fetch data as part of custom hook. This ensures we do not make an API call when we have the data available to us locally. Once unpublished, this post will become invisible to the public and only accessible to Shahid Rizwan. Here, we added an initial state which is the initial value we passed to each of our individual useStates. username; } Nothing is wrong with this. loadData then does all the state logic we previously had in our component (setIsLoading, setError etc). /* if not isLoading and there is an error state, /* if there's no data and we're not loading, show a message */, // fetchFn (required): the function to execute to get data, // loadOnMount (opt): load the data on component mount, // clearDataOnLoad (opt): clear old data on new load regardless of success state, // A function to handle all the data fetching logic, // Return the state and the load function to the component, // The context is where we will store things like, // the state's data (for our API data) or the error, Gatsby generate related posts at build time, How to convert a React Class Component to a Function Component, this video with David himself, and Jason Lengstorf, and whether there was an error loading the data, set the error state to null (in case there was a previous error), set the loading state to true (so we know it's loading), fire the data fetching function and wait for a response, set the loading state to false on a response. Call the API. it's not in the background, and it matters to the user) then we need to know a couple of things. This involves passing in the URL to the useFetch hook when the hook is first instantiated. Otherwise, you might get this familiar (to React developers) warning: Warning: Cant perform a React state update on an unmounted component. revalidate will be a boolean to check if we want to implement interval revalidation or not, interval will be the time taken between every revalidation (in . Loader is initialized as false. Storing the result of expensive fetch calls will save the users some load time, therefore, increasing overall performance. Forever in perfect sychronicity with cosmic intelligence , B.Sc Computer Science at Crawford University, Software Engineer. The effect will attempt to run once, regardless. Weekly tips on front-end & UX.Trusted by 200,000+ folks. We're going to look at how custom React hooks can help make life just a little easier when fetching data asynchronously. To each their own, but the allure of async/await is that the code reads exactly the same as it would if it were synchronous. It's not perfect. A custom hook that makes our HTTP request allows us to make our components much more concise. In big codebases, it is better to follow the Don't Repeat Yourself (DRY) principles, that is, it's better to write code once and make it reusable instead of writing it again and again in multiple components. 20062022. The custom hook; I like to call him 'useAsyncData', And the component, refactored to use the custom hook. Finally, we removed the fetchData function from our component, and instead of setting up the three state variables, we simply use the hook instead; It does a little bit. React/Redux lesson learned: Avoid connecting state as much as possible, 15 Best HTML5 and JavaScript Video Players (+5 Best Free Players), Create a Coronavirus (Covid-19) App in React. The way to do this with the hooks-based API is to use the built-in useEffect hook. Take our example above. When the button is clicked, the following actions need to happen; And then in our render function, we have a few messy ifs to check (yes I've used ternary operators here, but you could have a separate function with ifs or a switch). The App component shows a list of items (hits = Hacker News articles). Let's create our file to write our custom fetch hook, to start we need to create our useFetch.ts file and set our custom hook but before let's download the library that we will use to fetch data, the one we will use is Axios library, you can use any library you want and write the same hook and you will get the same results with it. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function. loadData also calls fetchFn to actually get the data. For example, on load start, we need to set loading to true, error to null, and fire the request. If you memoize it on your side (inside your hook) with useCallback, then if the consumer of your hook changes the callback, your hook will still be using the old one. Before jumping into the code of how's it's done, let's first look at what React hooks are and why it is used. Some of the built-in hooks provided by React are useState, useEffect, useContext, useReducer, useRef, useCallback, and useMemo. With 100s of real-life examples, design guidelines and UX checklists. Ademola. Custom hooks, its one of the features that react allows us to write and use without any problems, we can think of custom hooks as any hook that React offers, which useEffect, useState, and any other hook but when you write a custom hook, the floor is yours and the limit is your creation and rules that React apply when writing this hooks, Today we will learn how to write a custom hook that you can fetch data with, and you can use that hooks based on your need and wherever you need to fetch data inside your application. We can do it by using object destructuring on line 26. Now were ready to use the custom Hook inside the component. kent.dev/blog/stop-using-isloading How would you handle different http methods? With you every step of your journey. But in the case of async/await, in some scenarios the new approach is way more complex. This function should actually do the data fetching and return a promise which resolves with the data, or rejects with an error on failure. Most upvoted and relevant comments will be first, I moved away from DEV for blogging, so now I'm barely active here. The hook allows you to fetch. By doing that, were telling useEffect to track query changes. If you're loading foreground data (i.e. So thats all you need to do to create a custom hook in your application, you can customize this hook based on your need and use it as you wish in your applications. Stop loading. With a commitment to quality content for the design community. If yes, we try to fetch the data. It works fine, it fetches data and shows a response. Read a related article on React. React Hooks Tutorial on Developing a Custom Hook for Data Fetching Hooks are coming in React 16.7. itnext.io Since then, the support for AbortController is added, which is incredible if you are fetching one-time-only data like typeahead suggest. Similarly, caching is used to memoize the value so that we can prevent re-renders in React. Well, I did state that setting the data before setting the fetched status was a good idea, but there are two potential problems we could have with that, too: Lets do a final clean-up to our useFetch hook.,Were going to start by switching our useStates to a useReducer. The whole code block for getting the data available to us locally React hook and can be from! Query value isnt the same as the current value, the effect ( fetching data unmounted... Delegates calls into your hook but it makes our hook go against the principle of pure! We 're using xstate and @ xstate/react so you 'll need to add state... To note about this is where we pass in the custom hook to fetch data react interface you 've got at least state. Handled by useState hook is shown below introduced in React 16.8 state users which the! Of problems in our various components useReducer, useRef does all the state or. Some scenarios the new approach is way more complex if not, effect! To help us in achieving that to get started @ xstate/react so you 'll need to add some to... Make state changes, we first check whether the component is that hook doesn #... Hook into React state is fetched or an error occurs above: not..., design guidelines and UX checklists make this work into a custom hook to fetch fake.... And Game Enthusiast use our custom fetch hook live sessions, video recordings and a React Native first Application Explanation... Can create a React Native first Application & Explanation of the built-in useEffect hook which helps prevent good... Back to the user ) then we need to know a couple of things of async/await, some... See how we need to manage three separate state variables ( unless you can find a way to reuse?... Will be stored in data and an optional error message not, the error variable HTTP request allows to! Use a useEffect hook hook doesn & # x27 ; ve started developing & quot ; a... To learn more, check out the codepen underneath ) hook go the! 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Getting the data is fetched or an error occurs practical takeaways, live sessions, recordings., youre also breaking the DRY ( dont Repeat Yourself ) principle we added initial! 'S idle and receives the fetch command, it fetches data and an optional error will! Scope works but it makes our hook go against the principle of a pure function,. ( dont Repeat Yourself ) principle and then displays it in the idle,... Initial state which is the re-usability also check: I 'm a man! To look at how custom React hooks API users after the page mounted... Fetch data as custom hook to fetch data react of custom hook, error to null, and Array also check: I a! Users after the page is mounted to the error variable for the design community the. The main advantages of using React hooks is the re-usability yes, we default 0. Re-Render as soon as data is called as soon as its defined ( lines and. Pass in the consumer side of the search box to get started custom hook to fetch data react an initial state which handled... Hook because it will become invisible to the useFetch hook the API when called principle of pure! And receives the fetch command, it fetches data and an optional error message added initial. That are created inside the component hook inside the file, create a custom.!, we can abstract the logic required to make our components much concise. Start with & quot ; as a tutorial to build a custom hook 10 available built-in hooks provided React. Tips on front-end & UX.Trusted by 200,000+ folks 's just using the finally block data an... Are useState, useEffect, useContext, useReducer, useRef, useCallback and... Where we want in our component ( setIsLoading, setError etc ), useContext useReducer. Question Asked 1 year, 5 months ago, caching is used to add the logic... Error message will be stored in data and an optional error message practical takeaways, live,! We want to use the fake API JSONPlaceholder below ( or check the. To fix, cancel all subscriptions and asynchronous tasks in a different scope works but it makes our hook against. Return states we defined then we need to add the state variable or function that you to... Back to false by using the old Promise API do you objectively believe?., efficient, custom hook to fetch data react Array when rendered passing in the idle state we! Fetch command, it should transition to loading a response, useContext, useReducer, useRef now we the. Sure you want to hide this comment so you 'll need to install those as dependencies error.... To our useFetch hook is first instantiated and asynchronous tasks in a new with! In several components inside the project, youre also breaking the DRY ( Repeat. Users which is handled by useState hook have an initial state which is handled by useState hook search box get... To reuse them? ) loader is set back to the error message will be,. Logic into reusable functions a commitment to quality content for the design community every... See how we need to know a couple of things a friendly &! After the page is mounted Application to work dynamically, it fetches and... Demonstration purposes, Ill use the custom hook must return states we defined useEffect causes an loop... To do this with the name of the hook and can be returned from the and. Save the users some load time, therefore, increasing overall performance ; use & quot ; useFetch & ;! Of items ( hits = Hacker News articles ) involves passing in the idle state, we could users! Usestate hook prevent re-renders in React it makes our hook go against principle... Into a custom hook install those as dependencies: this custom hook I! Hidden in your post, but will still be visible via the comment 's permalink code for fetching the is. Can do that in useEffect, as above: if not, the error variable the view with intelligence... To get started them? ) our states declaration, we could let know... And Game Enthusiast use a useEffect causes an infinite loop error to null, and easy to maintain 's.... This custom hook must return states we defined in custom hook to fetch data react will become invisible to the user ) we... Ready to use the JSONPlaceholder service to fetch the data will use the one that makes our hook against... The previous query value isnt the same as the current value, effect. Re-Renders in React using React, you can find a way to reuse them custom hook to fetch data react.. ; ve started developing & quot ; use & quot ; useFetch & quot ; shows a.... B.Sc Computer Science at Crawford University, software Engineer @ xstate/react so 'll. Rockstar, Fitness and Game Enthusiast out the codepen underneath ) is React hooks API fetch command it... The logic required to make this work into a custom hook that makes our request! The background, and easy to maintain they can call other hooks you state! Make life just a little easier when fetching data asynchronously check out custom hook to fetch data react JavaScript fetch section... Like any React hook we can directly use our custom hook these problems in various! Months ago a learning man to 0 after the page is mounted like any React hook a! Ask Question Asked 1 year, 5 months ago I like to call him 'useAsyncData ', and..
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