React Hooks Multiple File upload example with Axios & Progress Bar

In this React tutorial, I will show you way to build React Hooks Multiple Files upload example using Axios and Multipart File for making HTTP requests, Bootstrap for progress bar and display list of files’ information (with download url).

More Practice:
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

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


React Hooks Multiple Files upload Overview

We’re gonna create a React Multiple Files upload application using Hooks, in that user can:

  • see the upload process (percentage) of each file with progress bars
  • view all uploaded files
  • download link to file when clicking on the file name

react-hooks-multiple-files-upload-example

When there is an error on uploading file:

react-hooks-multiple-files-upload-example-with-error-message

Technology

  • React 16/17
  • Axios 0.21.1
  • Bootstrap 4

Web API for File Upload & Storage

Here are APIs that we will use Axios to make HTTP requests:

MethodsUrlsActions
POST/uploadupload a File
GET/filesget 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 Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

Project Structure

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

react-hooks-multiple-files-upload-example-project-structure

Let me explain it briefly.

FileUploadService provides functions to save File and get Files using Axios.
FilesUpload contains multiple files upload form, progress bar, display of list files.
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 Hooks Multiple File Upload Project

Open cmd at the folder you want to save Project folder, run command:
npx create-react-app react-hooks-multiple-file-upload

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


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

Import Bootstrap to React Hooks Multiple File Upload App

Run command: npm install bootstrap.

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

import React from "react";
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 axios.
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");
};

const FileUploadService = {
  upload,
  getFiles,
};

export default FileUploadService; 

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

– Inside upload() function, 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 Page for Upload Multiple Files

Let’s create a File 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, useRef } from "react";
import UploadService from "../services/FileUploadService";

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

export default UploadFiles;

Then we define the state using React Hooks:

const UploadFiles = () => {

  const [selectedFiles, setSelectedFiles] = useState(undefined);
  const [progressInfos, setProgressInfos] = useState({ val: [] });
  const [message, setMessage] = useState([]);
  const [fileInfos, setFileInfos] = useState([]);
  const progressInfosRef = useRef(null)

  ...
}

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

const UploadFiles = () => {
  ...
  const selectFiles = (event) => {
    setSelectedFiles(event.target.files);
    setProgressInfos({ val: [] });
  };
  ...
}

We use selectedFiles array for accessing current selected Files. Every file has a corresponding progress Info (percentage, file name) and index in progressInfos array.

const UploadFiles = () => {
  ...
  const uploadFiles = () => {
    const files = Array.from(selectedFiles);

    let _progressInfos = files.map(file => ({ percentage: 0, fileName: file.name }));

    progressInfosRef.current = {
      val: _progressInfos,
    }

    const uploadPromises = files.map((file, i) => upload(i, file));

    Promise.all(uploadPromises)
      .then(() => UploadService.getFiles())
      .then((files) => {
        setFileInfos(files.data);
      });

    setMessage([]);
  };
  ...
}

In the code above, for each file, we invoke upload() function which call UploadService.upload() method with an index (i) parameter and return a Promise.

After all the processes are done, we call UploadService.getFiles() to get the files’ information and assign the result to fileInfos state, which is an array of {name, url} objects.

So create following upload() function like this:

const UploadFiles = () => {
  ...

  const upload = (idx, file) => {
    let _progressInfos = [...progressInfosRef.current.val];
    return UploadService.upload(file, (event) => {
      _progressInfos[idx].percentage = Math.round(
        (100 * event.loaded) / event.total
      );
      setProgressInfos({ val: _progressInfos });
    })
      .then(() => {
        setMessage((prevMessage) => ([
          ...prevMessage,
          "Uploaded the file successfully: " + file.name,
        ]));
      })
      .catch(() => {
        _progressInfos[idx].percentage = 0;
        setProgressInfos({ val: _progressInfos });

        setMessage((prevMessage) => ([
          ...prevMessage,
          "Could not upload the file: " + file.name,
        ]));
      });
  };
  ...
}

The progress will be calculated basing on event.loaded and event.total and percentage value is assigned to specific item of progressInfos by the index.

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

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

  ...
}

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

const UploadFiles = () => {
  ...

  return (
    <div>
      {progressInfos && progressInfos.val.length > 0 &&
        progressInfos.val.map((progressInfo, index) => (
          <div className="mb-2" key={index}>
            <span>{progressInfo.fileName}</span>
            <div className="progress">
              <div
                className="progress-bar progress-bar-info"
                role="progressbar"
                aria-valuenow={progressInfo.percentage}
                aria-valuemin="0"
                aria-valuemax="100"
                style={{ width: progressInfo.percentage + "%" }}
              >
                {progressInfo.percentage}%
              </div>
            </div>
          </div>
        ))}

      <div className="row my-3">
        <div className="col-8">
          <label className="btn btn-default p-0">
            <input type="file" multiple onChange={selectFiles} />
          </label>
        </div>

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

      {message.length > 0 && (
        <div className="alert alert-secondary" role="alert">
          <ul>
            {message.map((item, i) => {
              return <li key={i}>{item}</li>;
            })}
          </ul>
        </div>
      )}

      <div className="card">
        <div className="card-header">List of Files</div>
        <ul className="list-group list-group-flush">
          {fileInfos &&
            fileInfos.map((file, index) => (
              <li className="list-group-item" key={index}>
                <a href={file.url}>{file.name}</a>
              </li>
            ))}
        </ul>
      </div>
    </div>
  );
};

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

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

Don’t forget to export the function component:

const UploadFiles = () => {
  ...
}

export default UploadFiles;

Add Files Upload Page to App Component

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

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

import FilesUpload from "./components/FilesUpload";

function App() {
  return (
    <div className="container" style={{ width: "600px" }}>
      <div className="my-3">
        <h3>bezkoder.com</h3>
        <h4>React Hooks Multiple Files Upload</h4>
      </div>

      <FilesUpload />
    </div>
  );
}

export default App;

Configure Port for React File Upload App

Because most of HTTP Server use CORS configuration that accepts resource sharing retricted to some sites or ports, and if you use the Project in this Spring Boot Server or this Node.js Server, 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

Run this React File Upload Axios App with command: npm start.

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

Conclusion

Today we’re learned how to build an React.js application for multiple Files upload using Hooks, Axios, Bootstrap with Progress Bars. We also provide the ability to show list of files, upload progress percentage, and to download file from the server.

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 Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

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

react-js-multiple-image-upload-with-preview-example

Happy Learning! See you again.

Further Reading

Fullstack:
Spring Boot + React Redux example: Build a CRUD App
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 Redux + Node.js + Express + MySQL: CRUD example
React + Node.js + Express + PostgreSQL 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.

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