web: hosts: Add Host ID validation

src/rouse/web/hosts.py

@@ -63,19 +63,26 @@ class HostListController(controllers.BaseController):
 
 class HostController(controllers.BaseController):
 
-    def GET(self, request, host_id):
-        host = request.db.query(model.Host).get(host_id)
+    @staticmethod
+    def get_host(db, host_id):
+        try:
+            int(host_id)
+        except ValueError:
+            raise milla.HTTPNotFound
+        host = db.query(model.Host).get(host_id)
         if not host:
             raise milla.HTTPNotFound
+        return host
+
+    def GET(self, request, host_id):
+        host = self.get_host(request.db, host_id)
 
         response = request.ResponseClass()
         response.set_payload(None, host)
         return response
 
     def PUT(self, request, host_id):
-        host = request.db.query(model.Host).get(host_id)
-        if not host:
-            raise milla.HTTPNotFound
+        host = self.get_host(request.db, host_id)
 
         if request.content_type == 'application/json':
             data = request.json
@@ -95,9 +102,7 @@ class HostController(controllers.BaseController):
         return response
 
     def DELETE(self, request, host_id):
-        host = request.db.query(model.Host).get(host_id)
-        if not host:
-            raise milla.HTTPNotFound
+        host = self.get_host(request.db, host_id)
 
         request.db.delete(host)
         request.db.commit()