Dynamically add meta description based on route in Angular

First create a SEOService or Something like below:

import {Injectable} from '@angular/core'; 
import { Meta, Title } from '@angular/platform-browser';

@Injectable({
  provideIn: 'root' // Add this to ensure your SEO service will be app-wide available
})
export class SEOService {
  constructor(private title: Title, private meta: Meta) { }


  updateTitle(title: string) {
    this.title.setTitle(title);
  }

  updateOgUrl(url: string) {
    this.meta.updateTag({ name: 'og:url', content: url })
  }

  updateDescription(desc: string) {
    this.meta.updateTag({ name: 'description', content: desc })
  }
}

After injecting the SEOService in your component (app.component.ts preferably), set meta tags and title in OnInit method

ngOnInit() {
    this.router.events.pipe(
       filter((event) => event instanceof NavigationEnd),
       map(() => this.activatedRoute),
       map((route) => {
         while (route.firstChild) route = route.firstChild;
         return route;
       }),
       filter((route) => route.outlet === 'primary'),
       mergeMap((route) => route.data)
      )
      .subscribe((event) => {
        this._seoService.updateTitle(event['title']);
        this._seoService.updateOgUrl(event['ogUrl']);
        //Updating Description tag dynamically with title
        this._seoService.updateDescription(event['title'] + event['description'])
      }); 
    }

Then configure your routes like

      { 
        path: 'about', 
        component: AboutComponent,
        data: {
          title: 'About',
          description:'Description Meta Tag Content',
          ogUrl: 'your og url'
        } 
      },

IMHO this is a clear way of dealing with meta tags. You can update facebook and twitter specific tags easier.

Title and Meta are providers that were introduced in Angular 4 and supposed to do this on both server and client side.

To create or update title tag and description meta tag, it is:

import { Meta, Title } from '@angular/platform-browser';

...

constructor(public meta: Meta, public title: Title, ...) { ... }

...

this.meta.updateTag({ name: 'description', content: description }); 
this.title.setTitle(title);

Angular 6+ and RxJS 6+ solution for dynamically set title on route change

If/when you upgrade to Angular 6 this is the solution there.

This service will:

• Update meta title on route change.
• Option to override title for any reasons you want that.

Create/change your SEO/meta service to the following.

import { Injectable } from '@angular/core';
import { Title, Meta } from '@angular/platform-browser';
import { Router, NavigationEnd, ActivatedRoute } from '@angular/router';
import { filter, map, mergeMap } from 'rxjs/operators';

@Injectable({
    providedIn: 'root'
})
export class MetaService {
    constructor(
        private titleService: Title,
        private meta: Meta,
        private router: Router,
        private activatedRoute: ActivatedRoute
    ) { }

    updateMetaInfo(content, author, category) {
        this.meta.updateTag({ name: 'description', content: content });
        this.meta.updateTag({ name: 'author', content: author });
        this.meta.updateTag({ name: 'keywords', content: category });
    }

    updateTitle(title?: string) {
        if (!title) {
            this.router.events
                .pipe(
                    filter((event) => event instanceof NavigationEnd),
                    map(() => this.activatedRoute),
                    map((route) => {
                        while (route.firstChild) { route = route.firstChild; }
                        return route;
                    }),
                    filter((route) => route.outlet === 'primary'),
                    mergeMap((route) => route.data)).subscribe((event) => {
                        this.titleService.setTitle(event['title'] + ' | Site name');
                    });
        } else {
            this.titleService.setTitle(title + ' | Site name');
        }
    }
}

Import your service and call it in the contructor.

app.component.ts

constructor(private meta: MetaService) {
    this.meta.updateTitle();
}

And this still requires to format routes like this.

Route file.ts

{ 
    path: 'about', 
    component: AboutComponent,
    data: {
      title: 'About',
      description:'Description Meta Tag Content'
    } 
  },

Hope this will help for you and other people looking to update the title/meta dynamically in Angular 6.