Vue Multiple Files Upload with Axios, FormData and Progress Bars

bezkoder Vue.js

In this tutorial, I will show you way to build a Vue Multiple Files Upload example that uses Axios and Multipart File with FormData for making HTTP requests. You will also know how to add Bootstrap progress bar, show response message and display list of files’ information (with url) from Web API.

More Practice:
– Vue.js 2 CRUD Application with Vue Router & Axios
– Vue.js JWT Authentication with Vuex and Vue Router
– Vue Pagination with Axios and API example


Vue Multiple Files upload Overview

We’re gonna create a Vue.js Multiple Files upload application 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

vue-js-multiple-file-upload-axios-formdata-progress-bar

Technology

  • Vue 2.6
  • Axios 0.20.0
  • Bootstrap 4

Web API for File Upload & Storage

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

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 example

Setup Vue.js Multiple Files Upload Project

Open cmd at the folder you want to save Project folder, run command:
vue create vue-multiple-files-upload

You will see some options, choose default (babel, eslint).

Then we add Axios library with command: npm install axios.

Project Structure

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

vue-js-multiple-file-upload-axios-formdata-progress-bar-project-structure

– UploadFilesService provides methods to save File and get Files using Axios.
– UploadFiles component contains upload form for multiple files, progress bars, display of list files.
– App.vue is the container that we embed all Vue components.

– index.html for importing the Bootstrap.
– http-common.js initializes Axios with HTTP base Url and headers.
– We configure port for our App in vue.config.js

Add Bootstrap to the project

Open index.html and add following line into <head> tag:

<!DOCTYPE html>
<html lang="en">
  <head>
    ...
    <link type="text/css" rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" />
  </head>
  ...
</html>

Initialize Axios for Vue HTTP Client

Under src folder, we create http-common.js file like this:

import axios from "axios";

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

Remember to change the baseURL, it 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/UploadFilesService.js

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

class UploadFilesService {
  upload(file, onUploadProgress) {
    let formData = new FormData();

    formData.append("file", file);

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

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

export default new UploadFilesService();

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

– FormData is a data structure that can be used to store key-value pairs. We use it to build an object which corresponds to an HTML form with 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 the post() & get() method of Axios to send an HTTP POST & Get request to the File Upload server.

Create Component for Multiple Files Upload

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

First we create a Vue component template and import UploadFilesService:

components/UploadFiles.vue

<template>

</template>

<script>
import UploadService from "../services/UploadFilesService";

export default {
  name: "upload-files",
  data() {
    return {

    };
  },
  methods: {
  
  }
};
</script>

Then we define the some variables inside data()

export default {
  name: "upload-files",
  data() {
    return {
      selectedFiles: undefined,
      progressInfos: [],
      message: "",

      fileInfos: [],
    };
  },
};

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

export default {
  name: "upload-files",
  ...
  methods: {
    selectFile() {
      this.progressInfos = [];
      this.selectedFiles = event.target.files;
    }
  }
};

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

export default {
  name: "upload-files",
  ...
  methods: {
    ...
    uploadFiles() {
      this.message = "";

      for (let i = 0; i < this.selectedFiles.length; i++) {
        this.upload(i, this.selectedFiles[i]);
      }
    }
  }
};

We call UploadFilesService.upload() method on each file with a callback. So create following upload() method:

export default {
  name: "upload-files",
  ...
  methods: {
    ...
    upload(idx, file) {
      this.progressInfos[idx] = { percentage: 0, fileName: file.name };

      UploadService.upload(file, (event) => {
        this.progressInfos[idx].percentage = Math.round(100 * event.loaded / event.total);
      })
        .then((response) => {
          let prevMessage = this.message ? this.message + "\n" : "";
          this.message = prevMessage + response.data.message;

          return UploadService.getFiles();
        })
        .then((files) => {
          this.fileInfos = files.data;
        })
        .catch(() => {
          this.progressInfos[idx].percentage = 0;
          this.message = "Could not upload the file:" + file.name;
        });
    }
  }
};

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

We also need to do this work in mounted() method:

export default {
  name: "upload-files",
  ...
  mounted() {
    UploadService.getFiles().then((response) => {
      this.fileInfos = response.data;
    });
  }
};

Now we implement the HTML template of the Upload File UI. Add the following content to <template>:

<template>
  <div>
    <div v-if="progressInfos">
      <div class="mb-2"
        v-for="(progressInfo, index) in progressInfos"
        :key="index"
      >
        <span>{{progressInfo.fileName}}</span>
        <div class="progress">
          <div class="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>

    <label class="btn btn-default">
      <input type="file" multiple @change="selectFile" />
    </label>

    <button class="btn btn-success"
      :disabled="!selectedFiles"
      @click="uploadFiles"
    >
      Upload
    </button>

    <div v-if="message" class="alert alert-light" role="alert">
      <ul>
        <li v-for="(ms, i) in message.split('\n')" :key="i">
          {{ ms }}
        </li>
      </ul>
    </div>

    <div class="card">
      <div class="card-header">List of Files</div>
      <ul class="list-group list-group-flush">
        <li class="list-group-item"
          v-for="(file, index) in fileInfos"
          :key="index"
        >
          <a :href="file.url">{{ file.name }}</a>
        </li>
      </ul>
    </div>
  </div>
</template>

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

Add File Upload Component to App Component

Open App.vue and embed the UploadFiles Component with <upload-files> tag.

<template>
  <div id="app">
    <div class="container" style="width:600px">
      <div style="margin: 20px">
        <h3>bezkoder.com</h3>
        <h4>Vue.js multiple Files upload</h4>
      </div>

      <upload-files></upload-files>
    </div>
  </div>
</template>

<script>
import UploadFiles from "./components/UploadFiles";

export default {
  name: "App",
  components: {
    UploadFiles
  }
};
</script>

Configure Port for Vue Multiple Files 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 post or this tutorial for making Rest API Server, you need to configure the port.

In src folder, create vue.config.js file with following content:

module.exports = {
  devServer: {
    port: 8081
  }
}

We've set our app running at port 8081. vue.config.js will be automatically loaded by @vue/cli-service.

Run the App

Run this Vue.js Multiple Files Upload App with command: npm run serve.

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

Further Reading

Fullstack CRUD App:

Conclusion

Today we're learned how to build a Vue.js application for multiple Files upload using 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 MongoDB example
- Node.js Express File Upload to Google Cloud Storage example
- Spring Boot Multipart File upload (to static folder) example

Source Code

The source code for this Vue Client is uploaded to Github.