How to insert the ng-template into dynamically added external element in Angular?

To insert an ng-template into a dynamically added external element in Angular, you would typically use Angular directives to control where and how the template is rendered. However, for dynamically added external elements (elements that are added to the DOM outside of Angular’s normal rendering process), you will need to interact with Angular’s rendering engine at a lower level. Here’s a step-by-step approach to achieve this:

Angular17 came and if you are new then you must check below two links:

1. Angular 17 Basic Tutorials
2. Angular Free Templates

1. Define Your ng-template

First, ensure your ng-template is defined in your component’s template. Use a template reference variable to easily access it from your component class.

<ng-template #myTemplate>
  <!-- Your template content goes here -->
  <div>Hello from ng-template!</div>
</ng-template>

2. Access the Template in Component

Use ViewChild to access the ng-template in your component class. You’ll also need ViewContainerRef and TemplateRef from @angular/core to manipulate the template.

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
})
export class AppComponent {
  @ViewChild('myTemplate') myTemplate!: TemplateRef<any>;

  constructor(private viewContainerRef: ViewContainerRef) {}

  // Method to dynamically insert the template
  insertTemplateDynamically() {
    // Your logic to insert the template goes here
  }
}

3. Dynamically Add the External Element

Before you can insert the ng-template into the dynamically added element, you must first add this element to the DOM. You can do this by manipulating the DOM directly or by using Angular’s Renderer2 for a more Angular-friendly approach.

import { Renderer2, ElementRef, OnInit } from '@angular/core';

constructor(private renderer: Renderer2, private el: ElementRef) {}

ngOnInit() {
  const externalElement = this.renderer.createElement('div');
  this.renderer.appendChild(this.el.nativeElement, externalElement);
}

4. Insert the ng-template into the External Element

To insert the ng-template into this dynamically added external element, use the ViewContainerRef associated with the element where you want to insert the template. You might need to create a ViewContainerRef for the external element manually since it’s outside Angular’s component hierarchy.

insertTemplateIntoExternalElement(externalElement: HTMLElement) {
  const embeddedView = this.viewContainerRef.createEmbeddedView(this.myTemplate);
  this.renderer.appendChild(externalElement, embeddedView.rootNodes[0]);
}

Important Note: Direct DOM manipulations like these can lead to security vulnerabilities, such as XSS attacks. Always sanitize any user input or content that gets inserted into your templates or DOM. Angular provides the DomSanitizer service for sanitizing content.

Final Thoughts

Manipulating the DOM directly and inserting Angular templates into dynamically added external elements is an advanced technique that should be used judiciously. Always consider Angular’s data-binding and component-based architecture first for manipulating the DOM, as direct DOM access and manipulation can lead to less maintainable code and potential security issues.

Second Approach:

Inserting an ng-template into a dynamically added external element in Angular requires a multi-step approach. You have to first define your template, then use Angular’s rendering and view manipulation APIs to insert it dynamically. Here’s a step-by-step guide:

1. Define Your ng-template

First, you’ll need an ng-template that you wish to insert. Define it in your component’s template (HTML file) with a template reference variable that you can refer to in your TypeScript code.

<ng-template #myTemplate>
  <div>Dynamic content here!</div>
</ng-template>

2. Access the Template in Component

Use ViewChild to access the template within your component’s TypeScript file. You’ll also need to import TemplateRef and ViewContainerRef for manipulating this template.

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

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
})
export class MyComponent {
  @ViewChild('myTemplate') myTemplate!: TemplateRef<any>;

  constructor(private viewContainerRef: ViewContainerRef) {}
}

3. Insert the Template Dynamically

Now, to insert the ng-template dynamically into an external element, you’ll likely need a method that handles the insertion logic. If this external element is part of your component, you can directly access it. However, for truly external elements, you may need a different approach, like using Angular’s Renderer2 or directly manipulating the DOM (which is generally not recommended).

Here’s an example using Renderer2 to append the template to a body element:

import { Renderer2, RendererFactory2 } from '@angular/core';

private renderer: Renderer2;

constructor(rendererFactory: RendererFactory2, private viewContainerRef: ViewContainerRef) {
  this.renderer = rendererFactory.createRenderer(null, null);
}

insertTemplate() {
  const embeddedView = this.myTemplate.createEmbeddedView(null);
  this.viewContainerRef.insert(embeddedView);
  const element = (embeddedView.rootNodes[0] as HTMLElement);

  // Assuming you want to append to the body. Replace 'document.body' with your target element.
  this.renderer.appendChild(document.body, element);
}

Considerations

• Direct DOM Manipulation: Direct manipulation of the DOM is not recommended in Angular for most cases because it bypasses Angular’s change detection and sanitization. Prefer Angular’s Renderer2 or similar Angular-approved methods when possible.
• Dynamic Content Context: If your ng-template needs context (like variables passed into it), you can provide a context object when creating the embedded view. Replace null in createEmbeddedView(null) with your context object.

This approach uses Angular’s built-in mechanisms for template and view manipulation, ensuring compatibility with Angular’s change detection and security features. Always test these dynamic manipulations thoroughly to ensure they work as expected in your specific application context.