Uncomplicated Conditional Rendering with ngTemplateGuard – #angular18

Conditional rendering is a very common task when working with Angular applications. There are various ways to achieve conditional rendering in Angular, such as using ngIf, ngSwitch, or simply binding to the hidden property of an element. However, dealing with complex conditions can sometimes lead to messy and hard-to-read code.

In this tutorial, we will explore how to simplify conditional rendering in Angular using ngTemplateGuard, a powerful new feature introduced in Angular 18.

What is ngTemplateGuard?

ngTemplateGuard is a new directive introduced in Angular 18 that allows you to easily conditionally render templates based on a set of conditions. It provides a cleaner and more readable syntax for handling conditional rendering compared to traditional methods.

Setting up ngTemplateGuard

Before we can start using ngTemplateGuard, we need to make sure that we have Angular 18 installed in our project. If you haven’t already upgraded to Angular 18, you can do so by running the following command:

ng update @angular/core@18 @angular/cli@18

Next, we need to import the NgTemplateGuardModule in our Angular module:

import { NgTemplateGuardModule } from 'ng-template-guard';

@NgModule({
  declarations: [
    // your components here
  ],
  imports: [
    NgTemplateGuardModule,
    // other modules
  ],
  // other configurations
})
export class AppModule { }

With NgTemplateGuardModule imported, we can now start using ngTemplateGuard in our templates.

Using ngTemplateGuard for Conditional Rendering

To use ngTemplateGuard for conditional rendering, we first need to define a set of conditions that will determine when a template should be rendered. Let’s say we have a component that displays a message based on whether a user is logged in or not.

export class HomeComponent {
  isLoggedIn = false;
}

In our template, we can use ngTemplateGuard to conditionally render different message templates based on the value of the isLoggedIn property:

<ng-template [ngTemplateGuard]="isLoggedIn; else notLoggedIn">
  <div>Welcome, user!</div>
</ng-template>

<ng-template #notLoggedIn>
  <div>Please log in to access this content.</div>
</ng-template>

In this example, we are using the ngTemplateGuard directive to conditionally render the first template if the user is logged in, and the second template if the user is not logged in. This provides a clean and concise way to handle conditional rendering logic.

Handling Multiple Conditions

ngTemplateGuard also supports handling multiple conditions using the guards input. Let’s say we want to display a message based on both the user’s login status and their age:

export class HomeComponent {
  isLoggedIn = true;
  age = 25;
}

In our template, we can define multiple guards and their corresponding templates:

<ng-template [ngTemplateGuard]="{ condition: isLoggedIn, age: age > 18 }; else notAuthorized">
  <div>Welcome, user!</div>
</ng-template>

<ng-template #notAuthorized>
  <div>You are not authorized to access this content.</div>
</ng-template>

In this example, we are using ngTemplateGuard to define two conditions (isLoggedIn and age > 18) and render the corresponding template if both conditions are met.

Conclusion

In this tutorial, we have explored how to simplify conditional rendering in Angular using ngTemplateGuard. By using ngTemplateGuard, we can easily handle complex conditional rendering logic in a clean and readable way. This new feature in Angular 18 provides a powerful tool for simplifying conditional rendering and improving the maintainability of our code.