On Click on Button Opens a Gallery and Select That Image to Upload in Parse Server
Introduction
In this article, we volition talk about how to handle file uploads with VueJs. 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 appropriately. We volition besides learn to filter the upload file type, for example, nosotros only allow images, exercise not allow file blazon like PDF.
- Sourcecode: https://github.com/chybie/file-upload-vue
- Demo: https://vue-file-upload-1126b.firebaseapp.com/
File Upload UI & API
File upload consists of two parts: the UI (front-end) and the API (back-cease). Nosotros volition exist using VueJs to handle the UI role. Nosotros need a backend application to take 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:-
- File upload with Hapi.js: https://scotch.io/bar-talk/handling-file-uploads-with-hapi-js, or
- File upload with Express + Multer: https://scotch.io/tutorials/limited-file-uploads-with-multer, or
- Switch to whatever deject solution of your choice (Amazon S3, Google Drive, etc).
Nosotros will be using File upload with Hapi.js as our backend throughout this manufactures. Nosotros volition also learn the tricks to enable fake upload on the forepart-end.
Setup Project with Vue-Cli
Nosotros will exist using vue-cli to scaffold Vue.js projects. We volition exist using the webpack-uncomplicated project template.
# install cli npm install vue-cli -grand # then create projection, with sass # follow the instructions to install all necessary dependencies vue init webpack-simple file-upload-vue Alright, all set. Allow's continue 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 grade = "container" > <!--UPLOAD--> <course enctype = "multipart/class-data" novalidate v-if = "isInitial || isSaving" > <h1 > Upload images </h1 > <div form = "dropbox" > <input type = "file" multiple :name = "uploadFieldName" :disabled = "isSaving" @alter = "filesChange($event.target.proper name, $event.target.files); fileCount = $event.target.files.length" accept = "epitome/*" grade = "input-file" > <p 5-if = "isInitial" > Drag your file(s) hither to begin <br > or click to browse </p > <p v-if = "isSaving" > Uploading {{ fileCount }} files... </p > </div > </form > </div > </template > <!-- Javascript --> <script > </script > <!-- SASS styling --> <mode lang = "scss" > </fashion > Notes:-
- Our
App.vuecomponent consists of three role: template (HTML), script (Javascript) and styles (SASS). - Our template has an upload course.
- The course attribute
enctype="multipart/form-data"is important. To enable file upload, this attribute must be set. Learn more than near enctype here. - We have a file input
<input type="file" />to accept file upload. The propertymultipleindicate it'southward allow multiple file upload. Remove it for unmarried file upload. - We will handle the file input
changeeffect. Whenever the file input change (someone drop or select files), we volition trigger thefilesChangerole and pass in the control proper name and selected files$effect.target.files, and and so upload to server. - We limit the file input to have images only with the attribute
accept="image/*". - The file input will be disabled during upload, so user can merely drib / select files over again after upload complete.
- We capture the
fileCountof the when file changes. We use thefileCountvariable in displaying number of files uploadingUploading {{ fileCount }} files....
Manner our File Upload Component
Now, that's the interesting office. Currently, our component expect like this:
We demand to transform it to look like this:
Let'due south style it!
<!-- App.vue --> ... <!-- SASS styling --> <style lang="scss"> .dropbox { outline : 2px dashed grey; / * the nuance box * / outline-commencement : -10px; background : lightcyan; color : dimgray; padding : 10px 10px; min-height : 200px; / * minimum height * / position : relative; cursor : pointer; } .input-file { opacity : 0; / * invisible simply it's there! * / width : 100%; height : 200px; position : absolute; cursor : pointer; } .dropbox : hover { background : lightblue; / * when mouse over to the drop zone, modify color * / } .dropbox p { font-size : one.2em; text-align : heart; padding : 50px 0; } </style> With only few lines of scss, our component looks prettier now.
Notes:-
- We make the file input invisible by applying
opacity: 0mode. This doesn't hide the file input, it just arrive invisible. - Then, we style the file input parent element, the
dropboxcss class. We get in look like a drop file zone surround with dash. - Then, we align the text inside dropbox to center.
File Upload Component Lawmaking
Let's go on 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 ; consign default { name : 'app' , data ( ) { return { uploadedFiles : [ ] , uploadError : zero , 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 grade to initial state this .currentStatus = STATUS_INITIAL ; this .uploadedFiles = [ ] ; this .uploadError = nada ; } , 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 ( Assortment (fileList.length) . keys ( ) ) . map ( x => { formData. append (fieldName, fileList[x] , fileList[x] .name) ; } ) ; // salvage it this . salvage (formData) ; } } , mounted ( ) { this . reset ( ) ; } , } < /script> Notes:-
- Our component will have a few statuses: STATUS_INITIAL, STATUS_SAVING, STATUS_SUCCESS, STATUS_FAILED, the variable name is pretty expressive themselves.
- After, we volition telephone call the Hapi.js file upload API to upload images, the API have a field call
photos. That's our file input field name. - We handle the file changes with the
filesChangepart.FileListis an object returned by the files holding of the HTML <input> element. Information technology let united states of america to admission the listing of files selected with the <input blazon="file"> element. Learn more [here]((https://developer.mozilla.org/en/docs/Web/API/FileList). - Nosotros so create a new
FormData, and suspend all ourphotosfiles to it.FormDatainterface provides a mode to hands construct a set of key/value pairs representing form fields and their values. Acquire more hither. - The
savepart will call our file upload service (hang on, we volition create the service adjacent!). We also set the status according to the result. -
mount()is the vue component life cycle hook. During that bespeak, we volition fix our component condition to initial state.
File Upload Service
Let's proceed to create our service. Nosotros will be using axios to brand HTTP calls.
Install axios
# install axios npm install axios --relieve Service
// file-upload.service.js import * equally axios from 'axios' ; const BASE_URL = 'http://localhost:3001' ; function upload ( formData ) { const url = ` ${ BASE_URL } /photos/upload ` ; render axios. post (url, formData) // become data . and then ( x => x.data) // add together url field . and so ( x => x. map ( img => Object. assign ( { } , img, { url : ` ${ BASE_URL } /images/ ${img.id} ` } ) ) ) ; } export { upload } Nil much, the lawmaking is pretty expressive itself. We upload the files, wait for the upshot, 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 starting time your backend server)
Display Success and Failed Result
We can upload the files successfully at present. Nevertheless, in that location'southward 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 form = "listing-unstyled" > <li v-for = "item in uploadedFiles" > <img :src = "detail.url" class = "img-responsive img-thumbnail" :alt = "item.originalName" > </li > </ul > </div > <!--FAILED--> <div five-if = "isFailed" > <h2 > Uploaded failed. </h2 > <p > <a href = "javascript:void(0)" @click = "reset()" > Endeavor once more </a > </p > <pre > {{ uploadError }} </pre > </div > </div > </div > </template > Notes:-
- Display the uploaded image when upload successfully.
- Display the error bulletin when upload failed.
Simulated the Upload in Forepart-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.false.service.js part upload ( formData ) { const photos = formData. getAll ( 'photos' ) ; const promises = photos. map ( ( x ) => getImage (ten) . then ( img => ( { id : img, originalName : ten.proper noun, fileName : x.name, url : img } ) ) ) ; return Promise. all (promises) ; } function getImage ( file ) { return new Promise ( ( resolve, refuse ) => { const fReader = new FileReader ( ) ; const img = document. createElement ( 'img' ) ; fReader. onload = ( ) => { img.src = fReader.result; resolve ( getBase64Image (img) ) ; } fReader. readAsDataURL (file) ; } ) } role getBase64Image ( img ) { const canvas = certificate. createElement ( 'canvas' ) ; canvass.width = img.width; sail.height = img.acme; const ctx = canvas. getContext ( '2nd' ) ; ctx. drawImage (img, 0 , 0 ) ; const dataURL = canvas. toDataURL ( 'image/png' ) ; return dataURL; } export { upload } Came across this solution in this Stackoverflow postal service. Pretty useful. My online demo is using this service.
Basically, what the lawmaking practice is read the source, draw it in canvas, and salve it as information url with the canvas toDataURL part. Learn more almost canvas hither.
At present you can swap the existent service with the simulated 1.
< ! -- 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! End your backend API, refresh your browser, you should see our app is still working, calling faux service instead.
Bonus: Delay Your Promises
Sometimes, you may desire to delay the promises to see the state changes. In our case, the file upload may consummate too fast. Let'southward write a helper role for that.
// utils.js // utils to filibuster promise office look ( ms ) { return ( x ) => { return new Promise ( resolve => setTimeout ( ( ) => resolve (10) , ms) ) ; } ; } export { await } So, yous tin use it in your component
< ! -- App.vue -- > ... < ! -- Javascript -- > <script> import { wait } from './utils' ; ... save ( formData ) { ... . upload (formData) . and so ( await ( 1500 ) ) // DEV ONLY: wait for 1.5s . then ( x => { this .uploadedFiles = [ ] . concat (10) ; this .currentStatus = STATUS_SUCCESS ; } ) ... } , < /script> Conclusion
That's it. This is how yous can handle file upload without using whatever tertiary party libraries and plugins in Vue. Information technology isn't that hard right?
Happy coding!
The UI (Front-terminate)
- Sourcecode: https://github.com/chybie/file-upload-vue
- Demo: https://vue-file-upload-1126b.firebaseapp.com/
The API (Back-finish) Tutorials and Sourcode
- File upload with Hapi.js: https://scotch.io/bar-talk/handling-file-uploads-with-hapi-js, or
- File upload with Express + Multer: https://scotch.io/tutorials/limited-file-uploads-with-multer, or
- Switch to any cloud solution of your selection (Amazon S3, Google Bulldoze, etc).
Source: https://www.digitalocean.com/community/tutorials/how-to-handle-file-uploads-in-vue-2
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