React.js Image Upload with Preview (Functional Component)

In this tutorial, I will show you way to build React.js Image Upload with Preview (functional component) to a Rest API. The React App uses Axios and Multipart File for making HTTP requests, Bootstrap for progress bar. You also have a display list of images’ information (with download url).

More Practice:
React Multiple Images Upload with Preview example
Drag and Drop File Upload with React Hooks example
React Hooks CRUD example with Axios and Web API
React Form Validation with Hooks example
React Hooks: JWT Authentication (without Redux) example
React + Redux: JWT Authentication example
React Custom Hook

Serverless:
React Hooks + Firebase Realtime Database: CRUD App
React Hooks + Firestore example: CRUD app

Using React Components instead:
React.js Image Upload with Preview Display example


Overview

We’re gonna create a React.js Image upload with Preview example using Hooks in that user can:

  • display the preview of image before uploading
  • see the upload process (percentage) with progress bar
  • view all uploaded images
  • link to download the image when clicking on the file name

react-js-image-upload-preview-example

For multiple Images upload with preview, please visit:
React Multiple Images Upload with Preview example

multiple-image-upload-react-js-progress-bar-example

Technology

  • React 18/17/16
  • Axios 0.27.2
  • Bootstrap 4

Rest API for File Upload & Storage

Here is the API that our React App will work with:

Methods Urls Actions
POST /upload upload a File
GET /files get List of Files (name & url)
GET /files/[filename] download a File

You can find how to implement the Rest APIs Server at one of following posts:
Node.js Express File Upload Rest API example
Node.js Express File Upload to MongoDB example
Node.js Express File Upload to Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

Or: Spring Boot Multipart File upload (to database) example

React App for Image upload with preview

After building the React.js project is done, the folder structure will look like this:

react-js-image-upload-preview-project

Let me explain it briefly.

ImageUploadService provides methods to save File and get Files using Axios.
ImageUpload is a React.js functional component contains upload form, image preview, progress bar, display of list of images with download url.
App.js is the container that we embed all React components.

http-common.js initializes Axios with HTTP base Url and headers.
– We configure port for our App in .env

Setup React.js Image Upload with Preview Project

Open cmd at the folder you want to save Project folder, run command:
npx create-react-app react-js-image-upload-preview
Or: yarn create react-app react-js-image-upload-preview

After the process is done. We create additional folders and files like the following tree:


public
src
components
ImageUpload.js
services
FileUploadService.js
App.css
App.js
index.js
package.json

Import Bootstrap to React.js Image Upload App

Run command: npm install [email protected]
Or: yarn add [email protected]

Open src/App.js and modify the code inside it as following-

import React from "react";
import "./App.css";
import "bootstrap/dist/css/bootstrap.min.css";

function App() {
  return (
    ...
  );
}

export default App;

Initialize Axios for React HTTP Client

Let’s install axios with command: npm install [email protected].
Or: yarn add [email protected]

Under src folder, we create http-common.js file with following code:

import axios from "axios";

export default axios.create({
  baseURL: "http://localhost:8080",
  headers: {
    "Content-type": "application/json"
  }
});

You can change the baseURL that depends on REST APIs url that your Server configures.

Create Service for File Upload

This service will use Axios to send HTTP requests.
There are 2 functions:

  • upload(file): POST form data with a callback for tracking upload progress
  • getFiles(): GET list of Files’ information

services/FileUploadService.js

import http from "../http-common";

const upload = (file, onUploadProgress) => {
  let formData = new FormData();

  formData.append("file", file);

  return http.post("/upload", formData, {
    headers: {
      "Content-Type": "multipart/form-data",
    },
    onUploadProgress,
  });
};

const getFiles = () => {
  return http.get("/files");
};

export default {
  upload,
  getFiles,
};

– First we import Axios as http from http-common.js.

– Inside upload() method, we use FormData to store key-value pairs. It helps to build an object which corresponds to HTML form using append() method.

– We pass onUploadProgress to exposes progress events. This progress event are expensive (change detection for each event), so you should only use when you want to monitor it.

– We call Axios post() to send an HTTP POST for uploading a File to Rest APIs Server and get() method for HTTP GET request to retrieve all stored files.

Create Functional Component for Upload Images

Let’s create a Image Upload UI with Progress Bar, Card, Button and Message.

First we create a React template with React Hooks (useState, useEffect) and import FileUploadService:

components/FileUpload.js

import React, { useState, useEffect } from "react";
import UploadService from "../services/FileUploadService";

const ImageUpload = () => {
  
  return (
    
  );
};

export default ImageUpload;

Then we define the state using React Hooks:

const ImageUpload = () => {

  const [currentFile, setCurrentFile] = useState(undefined);
  const [previewImage, setPreviewImage] = useState(undefined);
  const [progress, setProgress] = useState(0);
  const [message, setMessage] = useState("");

  const [imageInfos, setImageInfos] = useState([]);

  ...
}

Next we define selectFile() method which helps us to get the selected Files from <input type="file" > element later.

const ImageUpload = () => {
  ...
  const selectFile = (event) => {
    setCurrentFile(event.target.files[0]);
    setPreviewImage(URL.createObjectURL(event.target.files[0]));
    setProgress(0);
    setMessage("");
  };

  ...
}

We use event.target.files[0] for accessing current File as the first Item.

We use URL.createObjectURL() static method to get the image preview URL as previewImage. This method produces a DOMString including a URL describing the object provided in the parameter. The URL life is tied to the document in the window on which it was created.

We call UploadService.upload() method on the currentFile with a callback. So create following upload() method:

const ImageUpload = () => {
  ...
  const upload = () => {
    setProgress(0);

    UploadService.upload(currentFile, (event) => {
      setProgress(Math.round((100 * event.loaded) / event.total));
    })
      .then((response) => {
        setMessage(response.data.message);
        return UploadService.getFiles();
      })
      .then((files) => {
        setImageInfos(files.data);
      })
      .catch((err) => {
        setProgress(0);

        if (err.response && err.response.data && err.response.data.message) {
          setMessage(err.response.data.message);
        } else {
          setMessage("Could not upload the Image!");
        }

        setCurrentFile(undefined);
      });
  };

  ...
}

The progress will be calculated basing on event.loaded and event.total.
If the transmission is done, we call UploadService.getFiles() to get the images’ information and assign the result to imageInfos state, which is an array of {name, url} objects.

We also need to do this work in the Effect Hook useEffect() method which serves the same purpose as componentDidMount():

const ImageUpload = () => {
  ...
  useEffect(() => {
    UploadService.getFiles().then((response) => {
      setImageInfos(response.data);
    });
  }, []);

}

Now we return the Upload File UI. Add the following code inside return() block:

const ImageUpload = () => {
  ...
  return (
    <div>
      <div className="row">
        <div className="col-8">
          <label className="btn btn-default p-0">
            <input type="file" accept="image/*" onChange={selectFile} />
          </label>
        </div>

        <div className="col-4">
          <button
            className="btn btn-success btn-sm"
            disabled={!currentFile}
            onClick={upload}
          >
            Upload
          </button>
        </div>
      </div>

      {currentFile && (
        <div className="progress my-3">
          <div
            className="progress-bar progress-bar-info"
            role="progressbar"
            aria-valuenow={progress}
            aria-valuemin="0"
            aria-valuemax="100"
            style={{ width: progress + "%" }}
          >
            {progress}%
          </div>
        </div>
      )}

      {previewImage && (
        <div>
          <img className="preview" src={previewImage} alt="" />
        </div>
      )}

      {message && (
        <div className="alert alert-secondary mt-3" role="alert">
          {message}
        </div>
      )}

      <div className="card mt-3">
        <div className="card-header">List of Images</div>
        <ul className="list-group list-group-flush">
          {imageInfos &&
            imageInfos.map((img, index) => (
              <li className="list-group-item" key={index}>
                <p>
                  <a href={img.url}>{img.name}</a>
                </p>
                <img src={img.url} alt={img.name} height="80px" />
              </li>
            ))}
        </ul>
      </div>
    </div>
  );
};

export default ImageUpload;

We allow only image format, so the input element will have accept="image/*" attribute.

In the code above, we use Bootstrap Progress Bar:

  • .progress as a wrapper
  • inner .progress-bar to indicate the progress
  • .progress-bar requires style to set the width by percentage
  • .progress-bar also requires role and some aria attributes to make it accessible
  • label of the progress bar is the text within it

The preview of uploading image is shown: <img className="preview" src={previewImage} alt="" />

To display List of uploaded images, we iterate over imageInfos array using map() function. On each image item, we use img.url as href attribute and img.name for showing text.

Add Image Upload Functional Component to App Component

Open App.js, import and embed the ImageUpload Component tag.

import React from "react";
import "./App.css";
import "bootstrap/dist/css/bootstrap.min.css";

import ImageUpload from "./components/ImageUpload";

function App() {
  return (
    <div className="container">
      <h3>bezkoder.com</h3>
      <h4>React.js Image Upload with Preview</h4>

      <div className="content">
        <ImageUpload />
      </div>
    </div>
  );
}

export default App;

App.css

.container{
  width: 600px !important;
  margin: 20px;
}

.content {
  margin: 20px 0;
}

.preview {
  max-width: 200px;
}

Configure Port for React Image Upload App

Because most of HTTP Server use CORS configuration that accepts resource sharing restricted to some sites or ports, and if you use the following Project for making Server:
Node.js Express File Upload Rest API example
Node.js Express File Upload to MongoDB example
Node.js Express File Upload to Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example
Or: Spring Boot Multipart File upload (to database) example

You need to configure port for our App.

In project folder, create .env file with following content:

PORT=8081

So our app will run at port 8081.

Run the App

You can find how to implement the Rest APIs Server at one of following posts:
Node.js Express File Upload Rest API example
Node.js Express File Upload to MongoDB example
Node.js Express File Upload to Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

Or: Spring Boot Multipart File upload (to database) example

Run this React File Upload Axios: npm start.
Or: yarn start.

Open Browser with url http://localhost:8081/ and check the result.

Conclusion

Today we’re learned how to build a React functional component application (React Hooks) for upload Images with Preview using Axios, Bootstrap with Progress Bar. We also provide the ability to show list of images, upload progress percentage, and to download Image from the server.

For Multiple Images Upload like this:
multiple-image-upload-react-js-progress-bar-example

Please visit:
React.js Multiple Images Upload with Preview example

Using React Components instead:
React.js Image Upload with Preview Display example

Happy Learning! See you again.

Further Reading

Fullstack:
React + Spring Boot + MySQL: CRUD example
React + Spring Boot + PostgreSQL: CRUD example
React + Spring Boot + MongoDB: CRUD example
React + Node.js + Express + MySQL: CRUD example
React + Node.js + Express + PostgreSQL example
React Redux + Node.js + Express + MySQL: CRUD example
React + Node.js + Express + MongoDB example
React + Django + Rest Framework example

Serverless:
React Hooks + Firebase Realtime Database: CRUD App
React Hooks + Firestore example: CRUD app

Source Code

You can find the complete source code for this tutorial at Github.

More Practice: Drag and Drop File Upload with React Hooks example