title: Getting Streets of a specific postcode using Open Street Maps
body: <p>I want to write a code that has the Countrycode and Postcode as an input and the ouput are the streets that are in the given postcode using some apis that use GSM.</p>
  
  <p>My tactic is as follows:</p>
  
  <ol>
  <li><p>I need to get the relation Id of the district. For Example 1991416 is the relation id for the third district in Vienna - Austria. It's provided by the nominatim api:  <a href="http://nominatim.openstreetmap.org/details.php?place_id=158947085" rel="nofollow">http://nominatim.openstreetmap.org/details.php?place_id=158947085</a></p></li>
  <li><p>Put the id in this api url:  <a href="http://polygons.openstreetmap.fr/get_wkt.py?id=1991416&amp;params=0" rel="nofollow">http://polygons.openstreetmap.fr/get_wkt.py?id=1991416&amp;params=0</a></p></li>
  <li><p>After downloading the polygon I can put the gathered polygon in this query on the overpass api</p>
  
  <p>(
  way
  (poly: "polygone data")
  ["highway"~"^(primary|secondary|tertiary|residential)$"]
  ["name"];</p>
  
  <p>);
  out geom;      </p></li>
  </ol>
  
  <p>And this gives me the streets of the searched district. My two problems with this solution are 
  1. that it takes quite a time, because asking three different APIs per request isn't that easy on ressources and 
  2. I don't know how to gather the relation Id from step one automatically. When I enter a Nominatim query like http:// nominatim.openstreetmap.org/search?format=json&amp;country=austria&amp;postalcode=1030 I just get various point in the district, but not the relation id of the searched district in order to get the desired polygone.</p>
  
  <p>So my questions are if someone can tell my how I can get the relation_Id in order to do the mentioned workflow or if there is another, maybe better way to work this issue out.</p>
  
  <h3>Thank you for your help!</h3>
  
  <p>Best Regards 
  Daniel</p>