Angular 10/9 ngTemplate & ngTemplateOutlet Example: Dynamic and Reusable Templates

In this tutorial, we'll see how to use ng-template and ngTemplateOutlet for creating dynamic and reusable template partials in Angular 10/9.

We'll see how to build a reusable component with an Angular 10 example using <ng-template> and we'll see what a template partial is.

We'll also see how to pass properties to our Angular 10 partial templates using the let- syntax.

Next, we'll see how to render a template partial using Angular ngtemplateoutlet in our Angular 10 example.

Build Reusable Components With Angular <ng-template>

In development, code reuse is essential for building complex apps. You can reuse something if it's appropriatly decoupled from the rest of your code. Angular provides many components that make building reusable code possible, among them it's <ng-template>.

Angular 10 Example with <ng-template>

Let's see a quick Angular 10 example that makes use of <ng-template>.

ng-template allows you to declare template partials. If you are familiar with template engines like Handlebars, you may have used template partials before.

What's an Template Partial?

A template partial refers to an Angular/HTML template that can be declared once and re-used in many places in your application. We can use template reference variables (#reference) to identify the template so we can reference it from other places.

Rendering of a Template Partial with Angular ngtemplateoutlet

This is an example template:

<ng-template #mytempate>  
  This is a partial template  
</ng-template>

You can render this template in your app using ngtemplateoutlet:

<ng-template #myTemplateRef>  
  This is a partial template  
</ng-template>

<div *ngTemplateOutlet="myTemplateRef">
</div> 

Passing Properties to Angular Partial Templates

We can also pass properties to our template using the let- syntax. First, let's change our ngTemplate to accept a message property:

<ng-template let-message="myMessage" #myTemplateRef>  

</ng-template>

Our template now is dynamic. It simply takes a message and renders it using interpolation.

In the same way, we can render the template using ngTemplateOutlet but this time we also need to pass a value for the message property. That's why we also need to use the context object which needs to contain the key-value pairs of all properties in your template:

<div *ngTemplateOutlet="myTemplateRef; context:{message: 'This is a partial template'}">
</div> 

Accessing Angular Template Partials in the DOM Using ViewChild

You can also access your template from the component class like you would access any DOM element using ViewChild:

import { Component, AfterViewInit, ViewChild  } from '@angular/core';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  implements AfterViewInit{
  @ViewChild('myTemplateRef') myTemplate; 

  ngAfterViewInit(){
    console.log(this.myTemplate)
  }
}

Conclusion

As a wrap-up, we've seen how to create template partials using ngTemplate and ngTemplateOutlet in a simple Angular 10 example.

We have leraned how to create a reusable component with an Angular 10 example using <ng-template> and seen what a template partial is.

We' learned to pass properties to our Angular 10 partial templates using the let- syntax and how to render a template partial using Angular ngtemplateoutlet in our Angular 10 example.

• Author: Ahmed Bouchefra Follow @ahmedbouchefra

• Date: 04 Aug 2020