Alternative Methods for Passing Parameters in Angular Routing

Understanding the routerLink Directive:

• The routerLink directive is used to navigate between different routes in an Angular application.
• It takes a string or an array of strings as its input, representing the URL path to navigate to.

Passing Parameters:

1. Using Template Variables:

   • Create a template variable within the routerLink directive to reference the parameter.
   • Use interpolation (${}) within the URL to dynamically insert the parameter value.

   <a routerLink="/products/{{ productId }}">View Product</a>
   

2. Using the RouterLinkActive Directive:

   • For more complex scenarios, combine routerLink with routerLinkActive to conditionally add a class based on the current route.
   • Use interpolation within the routerLink to pass the parameter.

   <a routerLink="/products/{{ productId }}" routerLinkActive="active">View Product</a>
   

3. • For even more control, use routerLinkActiveOptions to customize the behavior of routerLinkActive.
   • Pass the parameter within the routerLink as usual.

   <a routerLink="/products/{{ productId }}" routerLinkActive="active" [routerLinkActiveOptions]="{ exact: true }">View Product</a>
   

Example:

<a routerLink="/products/{{ product.id }}">View Product</a>

In this example, product.id is a template variable that holds the product's ID. The routerLink directive will navigate to the URL /products/1 if product.id is 1.

Key Points:

• Use template variables or expressions to dynamically generate the parameter value within the routerLink directive.
• Combine routerLink with routerLinkActive for conditional styling based on the current route.
• Use routerLinkActiveOptions for more fine-grained control over routerLinkActive behavior.

Passing Parameters to routerLink:

• <a routerLink="/products/{{ productId }}">View Product</a>
  

  This creates a link that navigates to /products/1 if productId is 1.

• <a routerLink="/products/{{ productId }}" routerLinkActive="active">View Product</a>
  

  This adds the active class to the link if the current route matches /products/{{ productId }}.

• <a routerLink="/products/{{ productId }}" routerLinkActive="active" [routerLinkActiveOptions]="{ exact: true }">View Product</a>
  

  This ensures that the active class is only added when the exact route matches.

Angular Router Parameter Passing:

• Retrieving Parameters in the Component:

  import { ActivatedRoute } from '@angular/router';
  
  constructor(private route: ActivatedRoute) {}
  
  ngOnInit() {
    this.route.paramMap.subscribe(params    => {
      const productId = params.get('productId');
      // Use productId to fetch product data
    });
  }
  

  This retrieves the productId parameter from the URL and uses it to fetch product data.

• <a routerLink="/products/{{ product.id }}">View Product</a>
  

  This passes the product.id as a parameter to the /products route.

• import { Router } from '@angular/router';
  
  constructor(private router: Router) {}
  
  navigateToProduct(productId: number) {
    this.router.navigate(['/products',    productId]);
  }
  

  This navigates to the /products route with the specified productId.

Complete Example:

import { Component, OnInit } from '@angular/core';
import { ActivatedRoute, Router } from '@angular/router';

@Component({
  selector: 'app-product-list',   
  templateUrl: './product-list.component.html',
  styleUrls: ['./product-list.component.css']
})
export class ProductListComponent implements    OnInit {
  products: Product[] = [];

  constructor(private route: ActivatedRoute, private    router: Router) {}

  ngOnInit() {
    this.route.paramMap.subscribe(params => {
      const productId = params.get('productId');
      // Fetch product data based on productId
      this.products = [
        { id: 1, name: 'Product 1' },
        { id: 2, name: 'Product 2' }
      ];
    });
  }

  navigateToProductDetails(productId: number) {
    this.router.navigate(['/products', productId]);
  }
}

<ul>
  <li *ngFor="let product of products">
    <a routerLink="/products/{{ product.id }}">{{ product.name }}</a>
  </li>
</ul>

Alternative Methods for Passing Parameters in Angular Routing

While the methods described in previous responses are common, there are a few alternative approaches you can consider:

Using Query Parameters:

• When to use: When you need to pass multiple, optional, or key-value pairs.
• Syntax: /products?productId=1&color=red
• In routerLink:

  <a routerLink="/products?productId={{ product.id }}&color=red">View Product</a>
  

• Retrieving in component:

  this.route.queryParams.subscribe(params => {
    const productId = params.get('productId');
    const color = params.get('color');
  });
  

• When to use: For hierarchical routing or when you need to pass parameters specific to a particular route segment.

Using a Custom Router Link Strategy:

• When to use: For more complex routing scenarios or to customize the routing behavior.
• Implementation: Create a custom RouterLinkStrategy class and provide it to the RouterModule configuration.
• Example:

  import { RouterLinkStrategy } from '@angular/router';
  
  class MyCustomRouterLinkStrategy implements RouterLinkStrategy {
    // Implement methods according to your needs
  }
  
  @NgModule({
    imports: [
      RouterModule.forRoot([], {
        useHash: true,
        strategy: MyCustomRouterLinkStrategy
      })
    ]
  })
  export class AppModule {}
  

Using Angular's Data Binding:

• When to use: When you need to pass data directly from a component to a child component.
• In parent component:

  <app-product-details [productId]="product.id"></app-product-details>
  

• In child component:

  @Input() productId: number;