verify existance of the service before accepting application

service/ApplicationService.js

 'use strict';
 const Application = require('../models/application');
+const Service = require('../models/service');
 
 /**
  * Submit a new application including the application documents for an administration case
@@ -10,12 +11,19 @@ const Application = require('../models/application');
 exports.postCaseApplication = function(body) {
   return new Promise(function(resolve, reject) {
     // TODO maybe remove VerfahrensId later (discuss with Peter)
-    var applicationRecord = Application.create(body).then(function(doc) {
-      doc.verfahrensId = doc.id
-      doc.save()
-      return doc
-    });
-    resolve(applicationRecord);
+    //Verify if the leikaId exists
+    const serviceRecord = Service.findOne({leikaId: body.leikaId}, function (err, result) {
+	    if (!result) {
+	        reject({error: 'The service with ID ' + body.leikaId + ' is not available here.'})
+	    } else {
+		    var applicationRecord = Application.create(body).then(function(doc) {
+		      doc.verfahrensId = doc.id
+		      doc.save()
+		      return doc
+		    });
+		    resolve(applicationRecord);
+	    }
+	});
   });
 }