Olá, me chamo Gustavo

import { Injectable, Http, Headers } from "@angular/core" ;

@ Injectable ( )

export class UserProvider {

constructor ( public http : Http ) { }

getUsers ( ) {

return this .http

. get ( "https://localhost:3001/users" )

. map ( ( res ) => res. json ( ) );

}

getUser ( id : number ) {

return this .http

. get ( "https://localhost:3001/users/" + id )

. map ( ( res ) => res. json ( ) );

}

addUser ( username : string , password : string ) {

let credentials = {

username : username ,

password : password ,

};

return this .http. post (

"https://localhost:3001/users" ,

JSON . stringify (credentials)
);

}