Uploading files is an integral part of most projects. However, when considering a file upload method, you should carefully assess the needs of your project. You can manually upload files using Angular components, like FormData, HttpClientModule, and reactive forms. Each of these components will serve different purposes.
In this article, you will learn about popular Angular components for file upload, including a quick tutorial on how to implement file upload in Angular 9.
What Is Angular?
The basic structure of Angular is based on NgModules, collections of components organized into functional sets. These modules enable you to define your Angular applications and integrate various components. Each application you create in Angular has a root module, which enables bootstrapping, and however many feature modules you need.
Within each module are components. These components define the views that are available for use in your application. Views are sets of screen elements that you can apply code to. Additionally, components include services. Services are classes that provide functionality and enable you to create efficient modular applications.
When you use components and the services inside, you are reliant on metadata to define types and usage. The metadata is what associates components with view templates, combining HTML with Angular directives and markup. This then enables you to modify HTML before rendering. Metadata is also how Angular makes services available via dependency injection.
Angular Components for File Upload
Within Angular, there are several components that you can use to achieve file uploads manually. Depending on how you want to use uploads, you may need to modify your use of these methods or you may be able to simply adopt pre-built file upload methods. For example, if you are using a digital asset management tool, many solutions provide methods you can add easily.
Below are the elements commonly used to accomplish file uploads with Angular.
FormData is an object you can use to store key-value pairs. It enables you to build an object that aligns with an HTML form. This functionality allows you to send data, such as file uploads, to REST API endpoints via HTTP client libraries or the XMLHttpRequest interface.
To create a FormData object you can use the following:
This method enables you to directly add key-values or to collect data from your existing HTML form.
HttpClientModule is a module that contains an API you can use to send and obtain data for your application from HTTP servers. It is based on the XMLHttpRequest interface. It includes features that enable you to avoid having to extract JSON data, use interceptors to modify request headers, and add interceptors to provider headers.
You can import this module by adding the following to your JSON package file:
Reactive forms enable you to use a model-driven approach for handling form inputs with changing values. With these forms, you can use multiple controls in a form group, validate form values, and construct forms in which you can dynamically modify controls. This is possible because form data is returned as an immutable, observable stream rather than a mutable data point as with template-driven forms.
You can import this module with the following:
How to Implement File Upload in Angular 9: Quick Tutorial
If you’re ready to try implementing file uploads with your Angular application you can try the following tutorial which uses the FormData and the HttpClientModule. This tutorial is adapted from a longer tutorial by Ahmed Bouchefra.
To get started with this tutorial, you’ll need the following:
1. Create New App and Start Development Server
To get started, you need to first create an application to handle uploads with. You can create a new application by entering the following into your terminal:
When you create this, you need to specify whether to add Angular routing (yes) and your stylesheet format (CSS).
Next, you need to start a local development server from your terminal:
This will start a server and return the local host address. Open the returned site in your browser to see your application.
2. Set up HttpClientModule
Initialize your project through the Angular CLI and import the HttpClientModule. To do this, you need to open your src/app/app.module.ts file. You can do this with the following:
3. Add Control Components and UI
To add UI control components you need to create a home and about components. You can add these in the terminal with the following:
To finish the UI, you can either create components manually or use additional modules like Angular Material. Whichever method you choose, you need to at least define your uploadFile() method and provide a button or submission method for your user.
You then need to add your components to your router via the following: src/app/app-routing.module.ts file.
4. Create Your Upload Service
First, you need to create your service with:
In the src/app/upload.service.ts file, add your imports and inject your HTTP client:
You also need to add your upload method which allows you to call the post method and send data to your upload server.
5. Define Your Upload Method
Once your service is created you need to define your upload method and add error handling. This is also where you can add progress bar elements and change your UI styling if you wish.
In the src/app/home/home.component.ts file, add your imports.
Now you can define your method and variables, and inject your upload service.
To enable users to submit files, you should also define an onClick() method to be tied to your submit button.
You can now test your application via the local browser to ensure that it functions as expected.
Hopefully, you now have enough information to experiment with Angular file upload components. If you’re new to the process, make sure to experiment in a test environment, or any place where you can safely learn from your mistakes. Continue experimenting and learning different types of approaches, until you’ll find a mix of methods that work best for you.