Angular 6 Image Upload in Asset Folder
In this example, nosotros will use Node.js as a backend server. And then first, nosotros install Athwart using Angular CLI and and so start working on this Angular file upload demo.
Angular file upload
To upload files in Angular, employ the ng2-file-upload library. For managing the uploaded files at the backend, we use the multer library. Multer is a node.js middleware for handling multipart/form-data, primarily used for uploading files. Information technology is written on top of the busboy for maximum efficiency. Therefore, Multer will not process any form which is not multipart.
To upload from scratch, follow the below steps. Only, first, we start this project by installing Angular on our machine.
Footstep one: Install Athwart.
If you have non installedAthwart CLI globally on your motorcar, install it using the post-obit command. We are using NPM as a bundle managing director for JS development.
TodayNPM is the biggest repository for any programming language, and information technology has almost every parcel you lot need in a web or mobile development project.npm means the node package manager. If you accept previous work with any front-end development stuff, this package manager is familiar.
In January 2020, over 700,000 packages were reported to be listed in the npm registry, making it the about meaning unmarried linguistic communication code repository on the planet.
npm install -k @athwart/cli # or yarn add global @athwart/cli
At present, create a local project using the following control.
ng new fileupload
At present, start the application using the post-obit control.
ng serve --open
Pace 2: Install the rxjs-compat library.
Since tertiary-party libraries do not support the RxJS, one change inAngular at present depends on the latest TypeScript and RxJS versions. And then, if you install third-party packages right now, it is not compatible with Angular.
In the time to come, all third-party libraries might upgrade their packages, but it is non compatible with Athwart.
So, to make full the gap betweenAngular and third-party packages, nosotros need to install the following library. That is it.
npm install rxjs-compat --save
Pace 3: Install Bootstrap 4.
Go to your concluding and type the following command.
npm install bootstrap --salvage
Later that, go to the insidesrcfolder, open up the styles.cssfile, and import the bootstrap.min.css file.
@import "~bootstrap/dist/css/bootstrap.min.css"
Footstep four: Install the ng-file-upload library.
Type the following control to install the library.
npm install ng2-file-upload --save
Now, write the following lawmaking insidean app.module.tsfile.
// app.module.ts import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { FileSelectDirective } from 'ng2-file-upload'; import { FormsModule } from '@angular/forms'; import { AppComponent } from './app.component'; @NgModule({ declarations: [ AppComponent, FileSelectDirective ], imports: [ BrowserModule, FormsModule ], providers: [], bootstrap: [AppComponent] }) export form AppModule { } We are using Angular Forms, the parcel included in Angular by default project.
Okay, so we have imported FormsModule and FileSelectDirective.
At present, write the following code inside anapp.component.tsfile.
// app.component.ts import { Component, OnInit } from '@angular/core'; import { FileUploader, FileSelectDirective } from 'ng2-file-upload/ng2-file-upload'; const URL = 'http://localhost:3000/api/upload'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent implements OnInit { title = 'app'; public uploader: FileUploader = new FileUploader({url: URL, itemAlias: 'photo'}); ngOnInit() { this.uploader.onAfterAddingFile = (file) => { file.withCredentials = imitation; }; this.uploader.onCompleteItem = (detail: any, response: any, status: any, headers: whatsoever) => { console.log('ImageUpload:uploaded:', item, condition, response); alert('File uploaded successfully'); }; } } Finally, write the post-obit lawmaking inside anapp.component.htmlfile.
<input type="file" name="photo" ng2FileSelect [uploader]="uploader" /> <push type="button" class="btn btn-success btn-due south" (click)="uploader.uploadAll()" [disabled]="!uploader.getNotUploadedItems().length" > Upload an Image </button>
Stride v: Create Node.js backend.
First, install the following node modules.
npm install express multer body-parser --salve
We have installed Express as a spider web framework for Node.js development.
Install nodemon as a dev dependency.
npm install nodemon --salve-dev
Create a new directory within root calleduploads.
Okay, now create one file in the projection root binder calledserver.js.
// server.js const path = crave('path'); const fs = require('fs'); const express = crave('express'); const multer = require('multer'); const bodyParser = require('torso-parser') const app = express(); const router = limited.Router(); const DIR = './uploads'; allow storage = multer.diskStorage({ destination: (req, file, cb) => { cb(cypher, DIR); }, filename: (req, file, cb) => { cb(null, file.fieldname + '-' + Engagement.now() + '.' + path.extname(file.originalname)); } }); let upload = multer({storage: storage}); app.use(bodyParser.json()); app.employ(bodyParser.urlencoded({extended: true})); app.use(role (req, res, next) { res.setHeader('Access-Control-Allow-Origin', 'http://localhost:4200'); res.setHeader('Admission-Control-Permit-Methods', 'Postal service'); res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type'); res.setHeader('Admission-Control-Allow-Credentials', truthful); next(); }); app.get('/api', part (req, res) { res.end('file catcher example'); }); app.mail service('/api/upload',upload.single('photograph'), function (req, res) { if (!req.file) { console.log("No file received"); render res.send({ success: false }); } else { console.log('file received'); return res.send({ success: true }) } }); const PORT = process.env.PORT || 3000; app.mind(PORT, part () { panel.log('Node.js server is running on port ' + PORT); }); In the above code, we accept defined the express router. Routing refers to how an application's endpoints (URIs) answer to customer requests.
The Limited Router class helps in the cosmos of route handlers.
Express apps utilize routers that are necessarily containers for a set of middleware. Nosotros can put this middleware holder but on a specific road, which allows u.s. to keep our logic in split files and bring them together on our terms.
Then, I have used a multermodule to store the file.
Multer adds the body object and the file or files object to a asking object. The body object contains the values of text fields of a class; a file or files object contains the files uploaded via the HTML form. Don't forget the enctype="multipart/form-information" in your HTML class.
Now, boot upwards the server using the following command.
nodemon server
Step 6: Run the projection.
Get-go both the server, if not started.
- ng server –open
- nodemon server
Get to thehttp://localhost:4200/
Until you have selected whatsoever file, the upload an prototype push button will remain disabled.
Upload an image, and come across the response yous get in the browser console.
I take too written an Angular 8 Image Upload Example in this blog.
You can change and resize the image on the node.js backend every bit well. I accept also written a tutorial on resizing image using node.js and Express.
Multer API
File data
Each file contains the following information:
| Fundamental | Description | Note |
|---|---|---|
fieldname | Field proper name specified in the form | |
originalname | Name of a file on the user's computer | |
encoding | Encoding blazon of the file | |
mimetype | The mime type of the file | |
size | Size of the file in bytes | |
destination | The folder to which a file has been saved | DiskStorage |
filename | The name of the file within thedestination | DiskStorage |
path | The full path to the uploaded file | DiskStorage |
buffer | ABuffer of the entire file | MemoryStorage |
#multer(opts)
Multer accepts the options object, the most basic of which is a dest property, which tells Multer where to upload the files on the server. If you omit the options object, the files will be kept in the memory and never written on the disk.
Past default, Multer will rename the files to avoid naming conflicts. However, the renaming part can be modified according to your needs.
The following are the main options that can exist passed to Multer.
| Key | Description |
|---|---|
dest orstorage | Where to shop the files |
fileFilter | Office to command which files are accepted |
limits | Limits of the uploaded data |
preservePath | Continue the full path of the files instead of just a base name |
An average web app might only be required and configured, every bit shown in the following example.
let upload=
If yous need more than control over your uploads procedure, you need to employ the storage pick instead of the dest option. Multer ships with storage enginesDiskStorage and the MemoryStorage; More than engines are available from third parties.
.single(fieldname)
Accept a single file with the name called fieldname. The single file will be stored inreq.file.
.array(fieldname[, maxCount])
Have the array of files, all with the proper nounfieldname. Optionally error out if more than files are uploaded. An array of files will be stored inreq.files.
.fields(fields)
Accept a mix of files, specified pastfields. An object with arrays of files will be stored inreq.files.
fields should be an assortment of objects withproper name and optionally amaxCount. Case:
name: 'avatar' maxCount:1
name: 'gallery' maxCount:viii
.none()
Accept only text fields. If any file upload is made, an error with code "LIMIT_UNEXPECTED_FILE" will be issued.
.whatever()
Accepts all files that come over the wire. An array of files will be stored in req.files.
Alarm: Ensure that you ever handle the files that a user uploads. Never add multer every bit a global middleware since a malicious user could upload files to a route you lot didn't anticipate. But use this office on routes where you are handling the uploaded files.
storage
DiskStorage
The disk storage engine gives you total control over storing files on a disk.
// server.js let storage = multer.diskStorage({ destination: function (req, file, cb) { cb(aught, '/tmp/my-uploads') }, filename: office (req, file, cb) { cb(null, file.fieldname + '-' + Date.now()) } }) let upload = multer({ storage: storage }) There are ii options bachelor,destination andfilename. They are both functions that determine where the file should be stored.
destination is used to determine within which folder the uploaded files should be stored. This can also be given as astring (e.thou.'/tmp/uploads'). If nodestination is given, the operating arrangement'south default directory for temporary files is used.
Annotation: Y'all are responsible for creating the directory when providing a destination as a function. When passing a string, multer volition ensure that the directory is created for you.
filename is used to determine what the file should be named inside the folder. Each file will be given a random proper name that doesn't include whatever file extension if no one is given.
Note: Multer volition not append any file extension for y'all; your function should return a filename complete with a file extension.
Each role gets passed both the asking (req) and some information about the file (file) to aid with the determination.
Note thatreq.trunk It might not have been fully populated all the same. It depends on how the customer transmits fields and files to the server.
#MemoryStorage
The memory storage engine stores the files in retention equallyBuffer objects. It doesn't have whatsoever options.
var storage=multer
var upload=
When using retention storage, the file info will contain a field calledbuffer that includes the unabridged file.
WARNING: Uploading huge files, or relatively small files in large numbers very speedily, can cause your application to run out of memory when retention storage is used.
#limits
An object specifying the size limits of the following optional properties. Multer passes this object into the busboy straight, and the details of the properties can be found on the busboy's page.
The following integer values are available:
| Fundamental | Description | Default |
|---|---|---|
fieldNameSize | Max field name size | 100 bytes |
fieldSize | Max field value size | 1MB |
fields | Max number of non-file fields | Infinity |
fileSize | For multipart forms, the max file size (in bytes) | Infinity |
files | For multipart forms, the max number of file fields | Infinity |
parts | For multipart forms, the max number of parts (fields + files) | Infinity |
headerPairs | For multipart forms, the max number of header key=>value pairs to parse | 2000 |
Specifying the limits can help protect your site against deprival of service (DoS) attacks.
#fileFilter
Set this to a role to command which files should be uploaded and skipped. The function should expect similar this:
// server.js function fileFilter (req, file, cb) { // The office should telephone call `cb` with a boolean // to indicate if the file should exist accepted // To reject this file laissez passer `imitation`, like so: cb(zilch, imitation) // To accept the file laissez passer `true`, like so: cb(null, true) // You lot tin can always laissez passer an error if something goes incorrect: cb(new Fault('I don\'t take a clue!')) } #Mistake handling
When encountering an error, Multer volition delegate the error to Limited. Thus, yous tin display a prissy error folio using the standard expressway.
If you desire to catch errors specifically from Multer, you can call the middleware office yourself. As well, if you're going to take hold of only the Multer errors, you can utilise the MulterError class that is attached to the multer object itself (e.thousand. err instanceof multer.MulterError).
// server.js var multer = crave('multer') var upload = multer().single('avatar') app.mail service('/profile', function (req, res) { upload(req, res, part (err) { if (err instanceof multer.MulterError) { // A Multer error occurred when uploading. } else if (err) { // An unknown fault occurred when uploading. } // Everything went fine. }) }) That'southward information technology for this tutorial. Thank you for taking it.
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Source: https://appdividend.com/2022/01/03/angular-file-upload/
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