angular2 - Pass value from parent route to child route

You may use a common service to pass data like explained in the Angular Documentation

Basically you may create a Service which will have a user object, which can be updated once your parent route gets loaded or with some action on parent component.

UserService

   import { Injectable } from '@angular/core';
   import { Subject }    from 'rxjs/Subject';

   @Injectable()
   export class UserService {
     // Observable user 
     user = new Subject<string>();
   }

And then when the child route component gets loaded you may retrieve the value from the Service.

HomeComponent

 @Component({
   ... 
 })
 export class HomeComponent{
   ... 
   constructor(private userService:UserService ){}
   someMethod = () =>{
      this.userService.user.next(<pass user object>);
   }
 }

MailComponent

 @Component({
   ... 
 })
 export class HomeComponent{
   ... 
   constructor(private userService:UserService ){
     this.userService.user.subscribe(userChanged);  
   }

   userChanged = (user) => {
     // Do stuff with user
   }
 }

Service object will be same instance in child if you add the provider in the parent.

Check out :- https://angular.io/docs/ts/latest/guide/router.html#!#link-parameters-array

You can pass data while changing routes on click as :-

<a [routerLink]="['/crisis-center', { foo: myVar }]">Crisis Center</a>