Instead of then() you can use the async/await statements when fetching data in React. In your fetching lifecycle method, you would have to toggle the property from false to true and when the data is resolved from true to false. Thus you can add a loading indicator during the time of waiting. Between both render() methods the fetched data is pending due to arriving asynchronously. The loading state should be used to indicated that an asynchronous request is happening. Both will improve your user experience for end-users of your application. But what else? There are two more properties that you could store in the state: loading state and error state. Of course you need the fetched data in your local state.
React fetch how to#
Note: If you want to get to know data fetching with a feature called React Hooks, checkout this comprehensive tutorial: How to fetch data with React Hooks? What about loading spinner and error handling? The most minimal example to fetch data would be the following:Įven though the render() method already ran once before the componentDidMount() method, you don't run into any null pointer exceptions because you have initialized the hits property in the local state with an empty array.
It uses JavaScript promises to resolve the asynchronous response. For the sake of simplicity, the article will showcase it with the native fetch API that comes with the browser. But how to fetch the data after all? React's ecosystem is a flexible framework, thus you can choose your own solution to fetch data. The componentDidMount() lifecycle method is the best place to fetch data. Afterward, the local state could be used in the render() method to display it or to pass it down as props. When this method runs, the component was already rendered once with the render() method, but it would render again when the fetched data would be stored in the local state of the component with setState(). There is another lifecycle method that is a perfect match to fetch data: componentDidMount(). The render() lifecycle method is mandatory to output a React element, because after all you may want to display the fetched data at some point. React's ES6 class components have lifecycle methods. But when should the data be fetched and how should it be fetched once the common parent component is agreed on? How to fetch data in React? That's basically everything on where to fetch the data in your React component hierarchy. Where do you want to show an optional error message when the request fails? Here the same rules from the second criteria for the loading indicator apply. Who is interested in this data? The fetching component should be a common parent component for all these components.ģ. Which level in your component hierarchy, to be more precise, which specific component, should fetch the data now? Basically it depends on three criteria:ġ. Now you are about to fetch a list of items from a third-party API. Imagine you already have a component tree that has several levels of components in its hierarchy. Where to fetch in React's component tree? How to fetch data from a GraphQL API in React?.How to fetch data in Higher-Order Components?.How to fetch data with Async/Await in React?.What about loading spinner and error handling?.Where to fetch in React's component tree?.Instead you will use React's local state management.
There is no external state management solution, such as Redux or MobX, involved to store your fetched data.
The article gives you a walkthrough on how to fetch data in React. However, at some point you want to request real world data from an own or a third-party API. That's good, because data fetching adds another layer of complexity to your application while taking the first steps in React. Usually they are confronted with Counter, Todo or TicTacToe applications. Newcomers to React often start with applications that don't need data fetching at all.
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