How to create React custom Hook with useFetch

How to create React custom Hook with useFetch

This article is about how to create custom hooks for data fetching. we'll explained and made a small demo to explain how we can declaratively fetch data and render it on screen by using the useFetch hook with the native fetch() API.

This article is about how to create custom hooks for data fetching. we'll explained and made a small demo to explain how we can declaratively fetch data and render it on screen by using the useFetch hook with the native fetch() API.

A custom hook is a JavaScript function with a unique naming convention that requires:

  1. the function name to start with use and
  2. the function may call other Hooks

Table of Contents

  • Abstracting fetch into useFetch()
  • Avoiding reference loops
  • useEffect’s return error
  • Handling errors
  • Setting loading indicators
  • Usage
  • Final thoughts 

The whole idea behind custom hooks is just so that we can extract component logic into reusable functions.

Often times as we build out React applications, we see ourselves writing almost the same exact codes in two or more different components. Ideally what we could do in such cases would be to extract that recurrent logic into a reusable piece of code (hook) and reuse it where the need be.

Before hooks, we share stateful logic between components using render props and higher order components, however, since the introduction of hooks and since we came to understand how neat they make these concepts, it no longer made sense to keep using those. Basically, when we want to share logic between two JavaScript functions, we extract it to a third function possibly because both components and hooks are equally just functions.

Abstracting fetch into useFetch()

The rationale behind this move is not different from what we have already explained above. Compared to using the native fetch API out of the box, abstracting it into the useFetch hook gives us a one-liner ability, more declarative code style, reusable logic and an overall cleaner code as we’ll see in a minute. Consider this simple useFetch example:

const useFetch = (url, options) => {
  const [response, setResponse] = React.useState(null);
  useEffect(async () => {
      const res = await fetch(url, options);
      const json = await res.json();
      setResponse(json);
  });
  return response;
};

Here, the effect hook called useEffect is used to perform to major functions —

  1. fetch the data with the native fetch API and
  2. Set the data in the local state of the component with the state hook’s update function.

Also notice that the promise resolving happens with async/await.

Avoiding reference loops

The effect hook runs on two occasions — When the component mounts and also when the component updates. What this means is, if nothing is done about the useFetch example above, we will most definitely run into a scary recurrent loop cycle. Why? Because we are setting the state after every data fetch, as a result, when we set the state, the component updates and the effect runs again.

Obviously, this will result in an infinite data fetching loop and we don’t want that. What we do want, is to only fetch data when the component mounts and we have a neat way of doing it. All we have to do is provide an empty array as second argument to the effect hook, this will stop it from activating on component updates but only when the component is mounted.

  useEffect(async () => {
      const res = await fetch(url, options);
      const json = await res.json();
      setResponse(json);
  }, []); // empty array

The second is an array containing all the variables on which the hook depends on. If any of the variables change, the hook runs again, but if the argument is an empty array, the hook doesn’t run when updating the component since there are no variables to watch.

useEffect’s return error

You may have noticed that in the effect hook above, we are using async/await to fetch data. However, according to documentation stipulations, every function annotated with async returns an implicit promise. So in our effect hook, we are returning an implicit promise whereas an effect hook should only return either nothing or a clean up function.

So by design, we are already breaking this rule because —

  1. We are not returning nothing
  2. A promise does not clean up anything

As a result, if we go ahead with the code as is, we will get a warning in the console pointing out the fact that useEffect function must return a cleanup function or nothing.

How to create React custom Hook with useEffect

Simply put, using async functions directly in the useEffect() function is frowned at. What we can do to fix this is exactly what is recommended in the warning above. Write the async function and use it inside the effect.

React.useEffect(() => {
    const fetchData = async () => {
      const res = await fetch(url, options);
      const json = await res.json();
      setResponse(json);
    };
    fetchData();
  }, []);

Instead of using the async function directly inside the effect function, we created a new async function fetchData() to perform the fetching operation and simply call the function inside useEffect. This way, we abide by the rule of returning nothing or just a cleanup function in an effect hook. And if you should check back on the console, you won’t see any more warnings.

Handling errors

One thing we haven’t mentioned or covered so far is how we can handle error boundaries in this concept. Well, it’s not complicated, when using async/await, it is common practice to use the good old try/catch construct for error handling and thankfully it will also work for us here.

const useFetch = (url, options) => {
  const [response, setResponse] = React.useState(null);
  const [error, setError] = React.useState(null);
  React.useEffect(() => {
    const fetchData = async () => {
      try {
        const res = await fetch(url, options);
        const json = await res.json();
        setResponse(json);
      } catch (error) {
        setError(error);
      }
    };
    fetchData();
  }, []);
  return { response, error };
};

Here, we used the very popular JavaScript try/catch syntax to set and handle error boundaries. The error itself is just another state initialized with a state hook so whenever the hook runs, the error state resets. However, whenever there is an error state, the component renders feedback to the user or practically you can perform any desired operation with it.

Setting loading indicators

You may already know this, but i still feel that it’ll be helpful to point out that you can use hooks to handle loading states for your fetching operations. The good thing is, It’s just another state variable managed by a state hook so if we wanted to implement a loading state in our last example, we’ll set the state variable and update our useFetch() function accordingly.

const useFetch = (url, options) => {
  const [response, setResponse] = React.useState(null);
  const [error, setError] = React.useState(null);
  const [isLoading, setIsLoading] = React.useState(false);
  React.useEffect(() => {
    const fetchData = async () => {
      setIsLoading(true);
      try {
        const res = await fetch(url, options);
        const json = await res.json();
        setResponse(json);
        setIsLoading(false)
      } catch (error) {
        setError(error);
      }
    };
    fetchData();
  }, []);
  return { response, error, isLoading };
    };

Usage

We cannot complete this tutorial without working on a hands-on demonstration to put everything we’ve talked about in practice. Let’s build a mini app that will fetch a bunch of dog images and their names. We’ll use useFetch to call the very good dog API for the data we’ll need for this app.

First we define our useFetch() function which is exactly the same as what we did before. We will simply reuse the one we created while demonstrating error handling above to explain the data fetching concept in practice since it already has most of the things we’ll need.

const useFetch = (url, options) => {
  const [response, setResponse] = React.useState(null);
  const [error, setError] = React.useState(null);
  React.useEffect(() => {
    const fetchData = async () => {
      try {
        const res = await fetch(url, options);
        const json = await res.json();
        setResponse(json);
      } catch (error) {
        setError(error);
      }
    };
    fetchData();
  }, []);
  return { response, error };
};

Next, we create the App() function that will actually use our useFetch() function to request for the dog data that we need and display it on screen.

function App() {
  const res = useFetch("https://dog.ceo/api/breeds/image/random", {});
  if (!res.response) {
    return Loading...

  }
  const dogName = res.response.status
  const imageUrl = res.response.message
  return (


        ### {dogName}






  );
}

Here, we just passed the url into the useFetch() function with an empty options object to fetch the data for the cat. It’s really that simple, nothing elaborate or complex. Once we’ve fetched the data, we just extract it from the response object and display it on screen. Here’s a demo on Codesandbox:

Final thoughts

Data fetching has always been an issue to contend with when building frontend-end applications, this is usually because of all the edge cases that you will need to account for. In this post, we have explained and made a small demo to explain how we can declaratively fetch data and render it on screen by using the useFetch hook with the native fetch() API.

reactjs

Bootstrap 5 Complete Course with Examples

Bootstrap 5 Tutorial - Bootstrap 5 Crash Course for Beginners

Nest.JS Tutorial for Beginners

Hello Vue 3: A First Look at Vue 3 and the Composition API

Building a simple Applications with Vue 3

Deno Crash Course: Explore Deno and Create a full REST API with Deno

How to Build a Real-time Chat App with Deno and WebSockets

Convert HTML to Markdown Online

HTML entity encoder decoder Online

Why ReactJS is better for Web Application Development?

Web Application Development is the point of contact for a business in today's digital era. It is important to choose the right platform for Web Application Development to build a high end Web

ReactJs Course | How to build a YouTube Clone using ReactJS

Hello, this is a new tutorial series about ReactJs. In this series, I will teach you two important topics. First, I will be teaching you what is ReactJs library and why this is so powerful and expandable. We will see what are the important...

Top Reasons to Choose ReactJS for Front-End Development - Prismetric

Why ReactJS is perfect choice for your next web application? Get to know all about ReactJS development and its benefits in detail for frontend development.

ReactJS Web App Development Services

We provide top-notch ReactJS development services to global clients. Hire expert ReactJS developers from top React JS development company, Skenix Infotech.

Highcharts with Reactjs

#reactjs #highcharts #therichpost https://therichpost.com/highcharts-with-reactjs-working-tutorial/ Highcharts with Reactjs Please like, share and subscribe....