title: Construct url step by step - Angular
body: <p>I'm trying to build a url step by step but I can not do it.
  I explain the situation: I realize an application for booking a coach online (step by step) with a angular material stepper. </p>
  
  <p>Step 1: will be to go to myapp/booking/coachs url (for a list of coaches).</p>
  
  <p>Step 2: grab the coach's id and add it to the url (myapp/booking/coachs/1). </p>
  
  <p>Step 3: choose a date (myapp/booking/coachs/1/date/2018-07-13), then choose a time available -> (myapp/booking/coachs/1/date/2018-07-13/hour/9)</p>
  
  <p>I can manage to get the id of the coach, etc., but I can not build the url step by step</p>
  
  <p>Can someone guide me in the right direction to do that, please?</p>