How to vue js 2.0 file upload and axios

How to vue js 2.0 file upload and axios

In this article, we will talk about how to handle file uploads with VueJs. vue js 2.0 file upload.. We will create an images uploader that allow user to upload single or multiple images file by drag and drop or select file dialog.

We will then upload the selected images and display them accordingly. We will also learn to filter the upload file type, for example, we only allow images, do not allow file type like PDF.

Table of Contents

File Upload UI & API

File upload consists of two parts: the UI (front-end) and the API (back-end). We will be using VueJs to handle the UI part. We need a backend application to accept the uploaded files. You may follow the backend tutorials or download and run either one of these server side application to handle file upload for your backend:-

We will be using File upload with Hapi.js as our backend throughout this articles. We will also learn the tricks to enable fake upload on the front-end.

Setup Project with Vue-Cli

We will be using vue-cli to scaffold Vue.js projects. We will be using the webpack-simple project template.

# install cli
npm install vue-cli -g

# then create project, with sass
# follow the instructions to install all necessary dependencies
vue init webpack-simple file-upload-vue

Alright, all set. Let's proceed to create our component.

File Upload Component

We will write our code in App.vue. Remove all the auto-generated code in the file.

<!-- App.vue -->

<!-- HTML Template -->
<template>
  <div id="app">
    <div class="container">
      <!--UPLOAD-->
      <form enctype="multipart/form-data" novalidate v-if="isInitial || isSaving">
        <h1>Upload images</h1>
        <div class="dropbox">
          <input type="file" multiple :name="uploadFieldName" :disabled="isSaving" @change="filesChange($event.target.name, $event.target.files); fileCount = $event.target.files.length"
            accept="image/*" class="input-file">
            <p v-if="isInitial">
              Drag your file(s) here to begin<br> or click to browse
            </p>
            <p v-if="isSaving">
              Uploading {{ fileCount }} files...
            </p>
        </div>
      </form>
  </div>
</template>

<!-- Javascript -->
<script>
</script>

<!-- SASS styling -->
<style lang="scss">
</style>

Notes:-

  1. Our App.vue component consists of 3 part: template (HTML), script (Javascript) and styles (SASS).
  2. Our template has an upload form.
  3. The form attribute enctype="multipart/form-data" is important. To enable file upload, this attribute must be set. Learn more about enctype here.
  4. We have a file input <input type="file" /> to accept file upload. The property multiple indicate it's allow multiple file upload. Remove it for single file upload.
  5. We will handle the file input change event. Whenever the file input change (someone drop or select files), we will trigger the filesChange function and pass in the control name and selected files $event.target.files, and then upload to server.
  6. We limit the file input to accept images only with the attribute accept="image/*".
  7. The file input will be disabled during upload, so user can only drop / select files again after upload complete.
  8. We capture the fileCount of the when file changes. We use the fileCount variable in displaying number of files uploading Uploading {{ fileCount }} files....
Style our File Upload Component

Now, that's the interesting part. Currently, our component look like this:

We need to transform it to look like this:

Let's style it!

<!-- App.vue -->
...

<!-- SASS styling -->
<style lang="scss">
  .dropbox {
    outline: 2px dashed grey; /* the dash box */
    outline-offset: -10px;
    background: lightcyan;
    color: dimgray;
    padding: 10px 10px;
    min-height: 200px; /* minimum height */
    position: relative;
    cursor: pointer;
  }

  .input-file {
    opacity: 0; /* invisible but it's there! */
    width: 100%;
    height: 200px;
    position: absolute;
    cursor: pointer;
  }

  .dropbox:hover {
    background: lightblue; /* when mouse over to the drop zone, change color */
  }

  .dropbox p {
    font-size: 1.2em;
    text-align: center;
    padding: 50px 0;
  }
</style>

With only few lines of scss, our component looks prettier now.

Notes:-

  1. We make the file input invisible by applying opacity: 0 style. This doesn't hide the file input, it just make it invisible.
  2. Then, we style the file input parent element, the dropbox css class. We make it look like a drop file zone surround with dash.
  3. Then, we align the text inside dropbox to center.
File Upload Component Code

Let's proceed to code our component.

<!-- App.vue -->
...

<!-- Javascript -->
<script>
  import { upload } from './file-upload.service';

  const STATUS_INITIAL = 0, STATUS_SAVING = 1, STATUS_SUCCESS = 2, STATUS_FAILED = 3;

  export default {
    name: 'app',
    data() {
      return {
        uploadedFiles: [],
        uploadError: null,
        currentStatus: null,
        uploadFieldName: 'photos'
      }
    },
    computed: {
      isInitial() {
        return this.currentStatus === STATUS_INITIAL;
      },
      isSaving() {
        return this.currentStatus === STATUS_SAVING;
      },
      isSuccess() {
        return this.currentStatus === STATUS_SUCCESS;
      },
      isFailed() {
        return this.currentStatus === STATUS_FAILED;
      }
    },
    methods: {
      reset() {
        // reset form to initial state
        this.currentStatus = STATUS_INITIAL;
        this.uploadedFiles = [];
        this.uploadError = null;
      },
      save(formData) {
        // upload data to the server
        this.currentStatus = STATUS_SAVING;

        upload(formData)
          .then(x => {
            this.uploadedFiles = [].concat(x);
            this.currentStatus = STATUS_SUCCESS;
          })
          .catch(err => {
            this.uploadError = err.response;
            this.currentStatus = STATUS_FAILED;
          });
      },
      filesChange(fieldName, fileList) {
        // handle file changes
        const formData = new FormData();

        if (!fileList.length) return;

        // append the files to FormData
        Array
          .from(Array(fileList.length).keys())
          .map(x => {
            formData.append(fieldName, fileList[x], fileList[x].name);
          });

        // save it
        this.save(formData);
      }
    },
    mounted() {
      this.reset();
    },
  }

</script>

Notes:-

  1. Our component will have a few statuses: STATUS_INITIAL, STATUS_SAVING, STATUS_SUCCESS, STATUS_FAILED, the variable name is pretty expressive themselves.
  2. Later on, we will call the Hapi.js file upload API to upload images, the API accept a field call photos. That's our file input field name.
  3. We handle the file changes with the filesChange function. FileList is an object returned by the files property of the HTML element. It allow us to access the list of files selected with the element. Learn more [here]((https://developer.mozilla.org/en/docs/Web/API/FileList).
  4. We then create a new FormData, and append all our photos files to it. FormData interface provides a way to easily construct a set of key/value pairs representing form fields and their values. Learn more here.
  5. The save function will call our file upload service (hang on, we will create the service next!). We also set the status according to the result.
  6. mount() is the vue component life cycle hook. During that point, we will set our component status to initial state.
File Upload Service

Let's proceed to create our service. We will be using axios to make HTTP calls.

Install axios

# install axios
npm install axios --save

Service

// file-upload.service.js

import * as axios from 'axios';

const BASE_URL = 'http://localhost:3001';

function upload(formData) {
    const url = `${BASE_URL}/photos/upload`;
    return axios.post(url, formData)
        // get data
        .then(x => x.data)
        // add url field
        .then(x => x.map(img => Object.assign({},
            img, { url: `${BASE_URL}/images/${img.id}` })));
}

export { upload }

Nothing much, the code is pretty expressive itself. We upload the files, wait for the result, map it accordingly.

You may run the application now with npm run dev command. Try uploading a couple of images, and it's working! (Remember to start your backend server)

Display Success and Failed Result

We can upload the files successfully now. However, there's no indication in UI. Let's update our HTML template.

<!-- App.vue -->

<!-- HTML Template -->
<template>
  <div id="app">
    <div class="container">
      ...form...

      <!--SUCCESS-->
      <div v-if="isSuccess">
        <h2>Uploaded {{ uploadedFiles.length }} file(s) successfully.</h2>
        <p>
          <a href="javascript:void(0)" @click="reset()">Upload again</a>
        </p>
        <ul class="list-unstyled">
          <li v-for="item in uploadedFiles">
            <img :src="item.url" class="img-responsive img-thumbnail" :alt="item.originalName">
          </li>
        </ul>
      </div>
      <!--FAILED-->
      <div v-if="isFailed">
        <h2>Uploaded failed.</h2>
        <p>
          <a href="javascript:void(0)" @click="reset()">Try again</a>
        </p>
        <pre>{{ uploadError }}</pre>
      </div>
    </div>
  </div>
</template>

Notes:-

  1. Display the uploaded image when upload successfully.
  2. Display the error message when upload failed.
Fake the Upload in Front-end

If you are lazy to start the back-end application (Hapi, Express, etc) to handle file upload. Here is a fake service to replace the file upload service.

// file-upload.fake.service.js

function upload(formData) {
    const photos = formData.getAll('photos');
    const promises = photos.map((x) => getImage(x)
        .then(img => ({
            id: img,
            originalName: x.name,
            fileName: x.name,
            url: img
        })));
    return Promise.all(promises);
}

function getImage(file) {
    return new Promise((resolve, reject) => {
        const fReader = new FileReader();
        const img = document.createElement('img');

        fReader.onload = () => {
            img.src = fReader.result;
            resolve(getBase64Image(img));
        }

        fReader.readAsDataURL(file);
    })
}

function getBase64Image(img) {
    const canvas = document.createElement('canvas');
    canvas.width = img.width;
    canvas.height = img.height;

    const ctx = canvas.getContext('2d');
    ctx.drawImage(img, 0, 0);

    const dataURL = canvas.toDataURL('image/png');

    return dataURL;
}

export { upload }

Came across this solution in this Stackoverflow post. Pretty useful. My online demo is using this service.

Basically, what the code do is read the source, draw it in canvas, and save it as data url with the canvas toDataURL function. Learn more about canvas here.

Now you can swap the real service with the fake one.

<!-- App.vue -->
...

<!-- Javascript -->
<script>
  // swap as you need
  import { upload } from './file-upload.fake.service'; // fake service
  // import { upload } from './file-upload.service';   // real service
</script>

...

Done! Stop your backend API, refresh your browser, you should see our app is still working, calling fake service instead.

Bonus: Delay Your Promises

Sometimes, you may want to delay the promises to see the state changes. In our case, the file upload may complete too fast. Let's write a helper function for that.

// utils.js

// utils to delay promise
function wait(ms) {
    return (x) => {
        return new Promise(resolve => setTimeout(() => resolve(x), ms));
    };
}

export { wait }

Then, you can use it in your component

<!-- App.vue -->
...

<!-- Javascript -->
<script>
  import { wait } from './utils';
  ...

  save(formData) {
     ....

        upload(formData)
          .then(wait(1500)) // DEV ONLY: wait for 1.5s 
          .then(x => {
            this.uploadedFiles = [].concat(x);
            this.currentStatus = STATUS_SUCCESS;
          })
         ...

      },
</script>
Summary

That's it. This is how you can handle file upload without using any 3rd party libraries and plugins in Vue. It isn't that hard right?

Happy coding!

The UI (Front-end)

The API (Back-end) Tutorials and Sourcode

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What are the differences between the various JavaScript frameworks? E.g. Vue.js, Angular.js, React.js

What are the differences? Do they each have specific use contexts?

What are the differences? Do they each have specific use contexts?

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

In this article we will discuss full details and comparison of both Ember.js and Vue.js

JavaScript was initially created to work for web applications. But today they have become the favorite of mobile app developers. Most of the developers prefer to work with frameworks based on JavaScript. It simplifies coding. You can use JavaScript with almost any framework.

The use of a particular framework will decide how easy and fast it is to create the app. So, you must choose the best one suited for the app that you are planning to build. You must make a wise choice so that you benefit in the end. Among the crowded market, two of the frameworks stand out. We will make a comparison between Ember.js and Vue.js.

Why Do You Select A Particular Framework?

Before we start comparing the two frameworks, we should understand the factors that lead to the choice of a framework. Each developer chooses a framework before he or she goes to work on an app. Let us see the reasons for the selection.

● The codes must be easy to understand and transparent.

● The framework should give the maximum power with the least amount of coding.

● The framework should provide a well laid out structure to work on.

● Does the framework support an in-built router or an external plug-in router?

● The framework should be able to transfer more data on a full page-load so that it becomes a single-page app. A single-page app is more beneficial for the application.

● In single page architectures if there is a need for users to share links to sub-screens within the interface, then the framework should have the capacity to route based on the URL.

● A tighter template option can help in enabling two-way binding.

● The framework should not conflict any third-party library.

● Testing the codes inside the framework should be easy.

● The framework should provide the HTTP client service for AJAX calls

● The documentation is essential. It should be complete and up-to-date.

● The framework should be compatible with the latest version of the browser.

● The framework has to fulfill the above conditions for easy construction of the app. You must ensure that the framework you choose meets the conditions.

Vue.js Explained

Developers are always looking at new frameworks to build their apps. The main requirements are speed and low cost. The framework should be easy to use by even new developers. You should be able to use it at low cost. Other considerations are about simple coding, proper documentation, etc.

Vue.js combines a lot of good when it comes to software language for web app development. The architecture of Vue.js is easy to put in use. The apps developed using Vue.js are easy to integrate with new apps.

Vue.js is a very lightweight framework. It makes it fast to download. It is also much faster than other frameworks. The single-file component nature of the framework is also beneficial. The size has made it very popular.

You can further decrease weight. With Vue.js you can separate the template-to-virtual DOM and compiler. You can only deploy the minified and zipped interpreter which is only 12 KB. You can compile the templates in your machine.

Another significant advantage of Vue.js is that it can integrate easily with existing applications created with JavaScript. It will make it easy for using this framework to make changes to applications already present.

Vue.js also integrates easily with other front-end libraries. You can plug in another library and make up for any deficiency in this framework. This feature makes this tool a versatile one.

Vue.js uses the method of rendering on the streaming-side server. You can render your component and get a readable stream. You can then send this to the HTTP server. It makes the server highly responsive. Your users will get the rendered content very quickly.

Vue.js is very SEO friendly. As the framework supports server-side rendering, the views are rendered directly on the server. The search engines list these.

But the most important thing for you is the ease with which you can learn Vue.js. The structure is elementary. Even new developers will find it easy to use it to build their apps. This framework helps in developing both small and large templates. It helps to save a lot of time.

You can go back and check your errors very easily. You can travel back and inspect all the states apart from testing your components. It is another important feature as far as any developer is concerned.

Vue.js also has very detailed documentation. It helps in writing your applications very quickly. You can build a web page or app with the basic knowledge of HTML or JavaScript.

● Vue.js has pure architecture. It helps in integration with other apps

● Vue.js is lightweight and fast. It can be made lighter by deploying only the interpreter

● You can separate the compiler and the template-to-virtual DOM.

● Due to smooth integration, you can use this to make changes to existing apps

● To make up for any shortfall, you can plug-in any library and makeup.

● As Vue.js uses streaming-side server rendering, your users can get quick responses.

● The server-side rendering also helps in being ranked higher by search engines.

● It has a simple structure. Easy to use for any new developer

● You can go back and check and correct your errors.

● You can check all the existing states.

● Detail documentation also helps build the web page or application very quickly.

Ember.js Decoded

Ember.js is an MVVM model framework. It is open-source software. This platform is mostly used for creating complex multi-page applications. It maintains up-to-date features without discarding any of the old features.

With this framework, you have to follow the architecture of the framework strictly. The JS framework is very tightly organized. It reduces the flexibility that other frameworks might offer.

There is a very refined and developed control system for its platforms and tools. You can integrate it with the new version with the tools provided. There is strict guidance about avoiding outdated APIs.

You can understand Ember’s APIs easily. They are also easy to work. You can make use of highly complex functionalities simply and straightforwardly.

The performance is better as similar jobs are processed together. It creates batches of similar bindings and DOM updates to improve the performance. It means that the browser needs to process them in one go. It will avoid recomputing for each task, wasting a lot of time.

You can write the codes in a simple manner and modules. You can use any of Ember’s APIs. It is possible due to the presence of Promises everywhere.

Ember comes with a well-written guide. The API is recorded in a useful manner. It is a front-end framework that is loaded. Ember has a router, pipeline, services, etc. of its own.

The basis for views, controllers, models, and framework is the Ember Object Model. All components come from the same objects. The framework is firm and steady. The reason is that all elements have similar jobs and characteristics.

Ember has made the general application, organization, and structure clear so that you don’t make any mistakes. You will have no chance to complicate the application unnecessarily. If you have to go out of the defined limits, you will have to force your way out.

The language used for templating in Embers is Handlebars. This language helps Embers to keep its logic out of view. The clean syntax of Handlebars makes it easy for you to read and understand the templates. Handlebar templates are faster to load.

Another advantage you gain from Handlebar is that you don’t have to update your template every time you add or remove data from the page. It will be done automatically by the language itself.

A community that is continually improving the framework supports Ember. They are updating the framework with the latest technology. They also make sure that backward compatibility is possible.

● Ember.js is an open-source MVVM model framework suitable for complex multiple-page applications.

● It offers both the latest and old features.

● It has a very tightly structured framework which doesn’t offer much flexibility

● A very refined control system helps you to integrate with new versions without any problem.

● There is strict guidance about avoiding outdated API versions.

● Ember’s APIs help you to use complex functionalities in a simple manner

● There is no recomputing for each task as the framework allows the browser to do similar functions together.

● Promises allow you to write modular and straightforward code using any API of Ember.js.

● Ember.js is a fully loaded, front-end framework.

● The framework is stable because all components have the same functionalities and properties.

● It has well-defined limitations which will prevent your complicating your application

● Handlebars, the language used by Ember.js allows you to read and understand templates easily. It also helps to load the templates faster.

● Handlebars will ensure to update the template every time you add or remove data.

● Ember.js has an active community that updates the framework regularly and facilitates backward compatibility.

A Comparison Between Ember.js And Vue.js

This article intends to compare the features of both frameworks. Let us see how the characteristics of these frameworks compare. It will help you to make use of the right framework for your web application.

When you need a modern engine for an old application, it is Vue.js which will help you. It combines the best properties of other frameworks. Vue.js is a developing framework. A ready-to-use library of interface elements does not exist. However, many third-party libraries can help you.

Ember.js offers you a well-organized and trustworthy framework. When the development team is big, this is the framework that suits best. It allows everyone to understand the written code and contribute to a common project. The technology will be up-to-date, and the platform will be stable.

Vue.js can help you use the syntax of different kinds. It helps in writing the codes with ease. It is also an SEO friendly framework. Ember is a fully loaded front-end framework and can help you develop the applications very fast. But it is not suitable for developing small projects.

It is not easy to say this is better than that. It will depend on what kind of project you have undertaken. Both have their pluses and minuses. The below table will help in a better comparison.

Final Thoughts

It is not easy to conclude as to which is better. It all depends on the application that you want to develop. Both frameworks are developing. Both are getting updates. Both the communities are working on the frameworks.

While Vue.js is more comfortable for writing codes, Ember is a full-stack framework allowing the development of apps very fast. It is suitable for big projects. It is too complicated to be used for smaller projects.

We hope you had a great time reading this article. If you’ve any questions or suggestions related to this blog, then feel free to ask them in the comment section. Thank You.!