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How to Setup Angular Code in ASP.NET Core Project

Jacques Hunt — Thu, 10 Aug 2023 03:55:42 +0000

Due to their low weight and high performance, Single-Page Applications, or SPAs, have recently become the most sought-after client facing application stacks. In this architecture, the client application renders the fetched data onto a fluid and dynamic layout while the server concentrates on data logic and provides data to the client in the form of RESTful APIs.

In addition to improving user experience, this can lessen the load placed on the webserver when rendering and serving HTML content over the network. In order to create the most effective SPAs, client-side frameworks like Angular, ReactJs, and Ionic have advanced significantly. Let’s discuss how to integrate an SPA powered by Angular inside of an existing ASP.NET Core application in this article.

Assume that the data source for an Angular application is an ASP.NET Core application. We now have two options for deployment: running two instances of both the client and server applications, with the client application configured with the server endpoint. Most of the real-world application deployments we see today are done in this manner.

A webserver like IIS or Apache must once again host an SPA, which is simply an index.html page with a few js files for runtime and client logic.

An innovative method has been developed that sandwiched an angular SPA inside an ASP.NET Core API because we would also need to require the client application to maintain the server address for communication.

With this method, both applications can be created and deployed on a single instance, and they are both local to one another. When a user calls the appropriate routes, the ASPNETCORE application also serves the client application to them. A few libraries must be added to the ASP.NET Core API, and the csproj file must be modified to allow for angular build activities.

Steps to Implement Code in ASP.NET Core

1. Start by copying the Angular application into the ClientApp subdirectory of the ASPNETCORE project. Together with the controllers and other projects, this is located in the root directory. Just keep in mind that since we’re using an ASPNETCORE API project, we don’t have a wwwroot folder or Views folder.

2. Install the package listed below, which supports SPA building and rendering, in the ASPNETCORE project.

3. To support SPA, we would need to add a few middlewares and services to the Startup class. The server application would route to an SPA when making specific requests technically because it is just a collection of static files under the ASPNETCORE project. We would also add support for the server to access these static files in order to make this possible.

The middleware functions UseStaticFiles() and UseSpa() for SPA support accomplish this.

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllersWithViews();
            
    // In production, the Angular files will be served from this directory
    services.AddSpaStaticFiles(configuration =>
    {
        configuration.RootPath = "ClientApp/dist";
    });
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseStaticFiles();
    
    // In Production Environment
    // Serve Spa static files
    if (!env.IsDevelopment())
    {
        app.UseSpaStaticFiles();
    }

    // other ASPNETCORE Routing Code
    // Spa middleware to enable
    // SPA request handling
    app.UseSpa(spa =>
    {
        // The directory from which the 
        // SPA files shall be served for
        // client requests
        spa.Options.SourcePath = "ClientApp";

        // When in Development,
        // Since the SPA app is not build
        // use npm start command to run 
        // the node server for local run
        if (env.IsDevelopment())
        {
            spa.UseAngularCliServer(npmScript: "start");
        }
    });
}

4. We make sure the angular build command configuration in the angular.json file of the client application, which is under the ClientApp directory, so that on angular build, the files are created under the /dist folder relative to the Client app path.

        "build": {
          "builder": "@angular-devkit/build-angular:browser",
          "options": {
            "progress": false,
            "extractCss": true,
            "outputPath": "dist", <-- ensure this path
            "index": "src/index.html",
            "main": "src/main.ts",
            "polyfills": "src/polyfills.ts",
            "tsConfig": "src/tsconfig.app.json",
            "assets": ["src/assets"],
            "styles": [
              "node_modules/bootstrap/dist/css/bootstrap.min.css",
              "src/styles.css"
            ],
            "scripts": []
          }
        }

This is significant because, when running, the ASPNETCORE application searches for the Spa files under the services-specified path /ClientApp/dist folder.Method AddSpaStaticFiles().

5. Finally, using the csproj and the changes listed below, we wire up the ClientApp and ASPNETCORE app together during project build.


  
    
    
    
    

    
    
      
      
      
        %(DistFiles.Identity)
        PreserveNewest
        true

In each of these configurations, we define $(SpaRoot) at the top of the csproj file as the ClientApp rootpath:


    netcoreapp3.1
    true
    Latest
    false

    
    ClientApp
    $(DefaultItemExcludes);$(SpaRoot)node_modules**
    
    false

When everything is finished, we can simply publish our project.

and run to see our changes coming into effect.

Angular Tips – Build Clean Forms Using Reactive Forms

Jacques Hunt — Thu, 25 Aug 2022 04:21:47 +0000

Reactive forms in Angular enable you to build clean forms without using too many directives. This is critical because:

JavaScript frameworks typically caution against using clustered templates
Form logic now lies in the component class

Essentially, Angular reactive forms give developers more control because every decision related to inputs and controls must be intentional and explicit.

To ensure the quality of your data, it’s always a good practice to validate reactive form input for accuracy and completeness. In this tutorial, we’ll show you how to validate reactive forms in Angular using FormBuilder.

To follow along, make sure you have the latest versions of Node.js (15.5.0) and Angular (11.0.5) installed, along with the Angular CLI (11.0.5). You can download the starter project on GitHub.

Form controls and form groups in Angular

Form controls are classes that can hold both the data values and the validation information of any form element, which means every form input you have in a reactive form should be bound by a form control. These are the basic units that make up reactive forms.

FormControl is a class in Angular that tracks the value and validation status of an individual form control. One of the three essential building blocks in Angular forms — along with FormGroup and FormArray — FormControl extends the AbstractControl class, which enables it to access the value, validation status, user interactions, and events.

Form groups are constructs that basically wrap a collection of form controls. Just as the control gives you access to the state of an element, the group gives the same access, but to the state of the wrapped controls. Every single form control in the form group is identified by name when initializing.

FormGroup is used with FormControl to track the value and validate the state of form control. In practice, FormGroup aggregates the values of each child FormControl into a single object, using each control name as the key. It calculates its status by reducing the status values of its children so that if one control in a group is invalid, the entire group is rendered invalid.

What is form validation in Angular?

Form validation in Angular enables you to verify that the input is accurate and complete. You can validate user input from the UI and display helpful validation messages in both template-driven and reactive forms.

When validating reactive forms in Angular, validator functions are added directly to the form control model in the component class. Angular calls these functions whenever the value of the control changes.

Validator functions can be either synchronous or asynchronous:

Synchronous validators take a control instance and return either a set of errors or null. When you create a FormControl, you can pass sync functions in as the second argument.
Asynchronous validators take a control instance and return a Promise or an Observable that later issues either a set of errors or null. You can pass async functions in as the third argument when you instantiate a FormControl.

Depending on the unique needs and goals of your project, you may choose to either write custom validator functions or use any of Angular’s built-in validators.

Without further ado, let’s get started building reactive forms.

What is `FormBuilder`?

Setting up form controls, especially for very long forms, can quickly become both monotonous and stressful. FormBuilder in Angular helps you streamline the process of building complex forms while avoiding repetition.

Put simply, FormBuilder provides syntactic sugar that eases the burden of creating instances of FormControl, FormGroup, or FormArray and reduces the amount of boilerplate required to build complex forms.

How to use `FormBuilder`

The example below shows how to build a reactive form in Angular using FormBuilder.

You should have downloaded and opened the starter project in VS Code. If you open the employee.component.ts, file it should look like this:

import { Component, OnInit } from '@angular/core';
import { FormControl, FormGroup } from '@angular/forms'
@Component({
  selector: 'app-employee',
  templateUrl: './employee.component.html',
  styleUrls: ['./employee.component.css']
})
export class EmployeeComponent implements OnInit {
  bioSection = new FormGroup({
    firstName: new FormControl(''),
    lastName: new FormControl(''),
    age: new FormControl(''),
    stackDetails: new FormGroup({
      stack: new FormControl(''),
      experience: new FormControl('')
    }),
    address: new FormGroup({
        country: new FormControl(''),
        city: new FormControl('')
    })
  });
constructor() { }
ngOnInit() {
  }
  callingFunction() {
    console.log(this.bioSection.value);
   }
}

You can see that every single form control — and even the form group that partitions it — is spelled out, so over time, you end up repeating yourself. FormBuilder helps solve this efficiency problem.

Registering `FormBuilder`

To use FormBuilder, you must first register it. To register FormBuilder in a component, import it from Angular forms:

import { FormBuilder } from ‘@angular/forms’;

The next step is to inject the form builder service, which is an injectable provider that comes with the reactive forms module. You can then use the form builder after injecting it. Navigate to the employee.component.ts file and copy in the code block below.

import { Component, OnInit } from '@angular/core';
import { FormBuilder } from '@angular/forms'
@Component({
  selector: 'app-employee',
  templateUrl: './employee.component.html',
  styleUrls: ['./employee.component.css']
})
export class EmployeeComponent implements OnInit {
  bioSection = this.fb.group({
    firstName: [''],
    lastName: [''],
    age: [''],
    stackDetails: this.fb.group({
      stack: [''],
      experience: ['']
    }),
    address: this.fb.group({
        country: [''],
        city: ['']
    })
  });
constructor(private fb: FormBuilder) { }
ngOnInit() {
  }
  callingFunction() {
    console.log(this.bioSection.value);
   }
}

This does exactly the same thing as the previous code block you saw at the start, but you can see there is a lot less code and more structure — and, thus, optimal usage of resources. Form builders not only help to make your reactive forms’ code efficient, but they are also important for form validation.

How to validate forms in Angular

Using reactive forms in Angular, you can validate your forms inside the form builders.

Run your application in development with the command:

ng serve

You will discover that the form submits even when you do not input values into the text boxes. This can easily be checked with form validators in reactive forms. The first thing to do, as with all elements of reactive forms, is to import it from Angular forms.

import { Validators } from '@angular/forms';

You can now play around with the validators by specifying the form controls that must be filled in order for the submit button to be active. Copy the code block below into the employee.component.ts file:

The last thing to do is to make sure the submit button’s active settings are set accordingly. Navigate to the employee.component.html file and make sure the submit statement looks like this:

If you run your application now, you will see that if you do not set an input for first name, you cannot submit the form — isn’t that cool?

Displaying input values and status

Let’s say you want to use the value and status properties to display, in real-time, the input values of your reactive form and whether it can be submitted or not.

The reactive forms API lets you use the value and status properties on your form group or form controls in the template section. Open your employee.component.html file and copy in the code block below:


    Bio Details


  
    First Name:
    
   


    Last Name:
    
   


    Age:
    
  

    Stack Details

    
      Stack:
      
     


    
      Experience:
      
    
  

    Address

    
      Country:
      
     


    
      City:
      
    
  

  
    Real-time data: {{ bioSection.value | json }}
  
  
    Your form status is : {{ bioSection.status }}

This displays both the value and the status for submission for you in the interface as you use the form. The complete code to this tutorial can be found here on GitHub.

Conclusion

This article gives an overview of the form builder and how it is a great efficiency enabler for form controls and form groups. It also shows how important it can be for handling form validation easily with reactive forms.

Angular InjectionToken Feature

Jacques Hunt — Fri, 19 Aug 2022 04:21:33 +0000

In this article, I want to talk about a feature which Angular provides, that isn’t particularly well known or used by many developers. When using Angular InjectionToken, we can specify a factory function which returns a default value of the parameterized type T. For example:

const WINDOW = new InjectionToken('A reference to the window object', {
  factory: () => window,
});

This sets up the InjectionToken using this factory as a provider, as if it was defined explicitly in the application’s root injector. Now we can use it anywhere in our application:

@Component({
  selector: 'my-app'
})
export class AppComponent {
  constructor(@Inject(WINDOW) window: Window) {}
}

But that’s not all. We can use the inject function to obtain a reference to other providers inside our factory function. Let’s see another real-world example:

import { inject, InjectionToken } from '@angular/core';
import { ActivatedRoute } from '@angular/router';

export type TimespanProvider = Observable;

export const TIMESPAN = new InjectionToken('Subscribe to timespan query param', {
  factory() {
    const activatedRoute = inject(ActivatedRoute);

    return activatedRoute.queryParams.pipe(
      pluck('timespan'),
      filterNil(),
      distinctUntilChanged()
    );
  },
});

In the above example, we inject the ActivatedRoute provider and return an observable for the timespan query param. Now we can use it in our components:

@Component({
  selector: 'app-home'
})
export class HomeComponent implements OnInit {
  constructor(@Inject(TIMESPAN) private timespan$: TimespanProvider) {}

  ngOnInit() {
    this.timespan$.pipe(untilDestroyed(this)).subscribe(console.log);
  }
}

We can also pass InjectionFlags to the inject function. For example, we can say that the requested provider is optional:

import { inject, InjectionToken, InjectFlags } from '@angular/core';

const MY_PROVIDER = new InjectionToken('', {
  factory: () => {
    const optional = inject(SomeProvider, InjectFlags.Optional);
    
    return optional ?? fallback;
  },
});

Here’s another real-world example — let’s say you have a theme service, which exposes the current user’s theme:

@Injectable({ providedIn: 'root' })
export class ThemeService {
  private theme = new Subject();
  theme$ = this.theme.asObservable();

  setTheme(theme: string) {
    this.theme.next(theme);
  }
}

The only data that most components need is the current theme. So instead of doing the following in each component:

@Component({
  selector: 'app-hello',
  template: `{{ theme$ | async }}`
})
export class HelloComponent {
  theme$: Observable;

  constructor(private themeService: ThemeService) {}

  ngOnInit() {
    this.theme$ = this.themeService.theme$;
  } 

}

We can create a provider with the sole purpose of providing the current user’s theme:

export type ActiveThemeProvider = Observable;
export const ACTIVE_THEME = new InjectionToken('Active theme', {
  factory() {
    return inject(ThemeService).theme$;
  }
});

@Component({
  template: `{{ theme$ | async }}`
})
export class HelloComponent {
  constructor(@Inject(ACTIVE_THEME) public theme$: ActiveThemeProvider) {}
}

In summary, the benefits of using the InjectionToken factory function are:

The provider is tree-shakeable, since we don’t need to inject it in our app module as we’d do with the useFactory provider.
Using inject() to request a provider is faster and more type-safe than providing an additional array of dependencies (which is the common usage of useFactory providers).
The provider has a single responsibility, and our components are injected only with the data they need.
It makes testing more straightforward because we don’t need to mock everything. We can return a mock value from the factory, and that’s all.

angular tutorial – ASP.NET Hosting Reviews and Guides

How to Setup Angular Code in ASP.NET Core Project

Steps to Implement Code in ASP.NET Core

Angular Tips – Build Clean Forms Using Reactive Forms

Form controls and form groups in Angular

What is form validation in Angular?

What is FormBuilder?

How to use FormBuilder

Registering FormBuilder

How to validate forms in Angular

Displaying input values and status

Bio Details

Stack Details

Address