Prvent user with the same user name to enter the same room

controllers/player.py

 from parameter_util import JSON_BODY, JSON_CONTAINS
-from http_util import FAIL, CODE_JSON, CODE_MISSING, CODE_SEMANTIC, CODE_GONE, CODE_NOTFOUND
-from room_util import ROOM_GET_CODE
+from http_util import FAIL, CODE_JSON, CODE_MISSING, CODE_SEMANTIC, CODE_GONE, CODE_NOTFOUND, CODE_CONFLICT
+from room_util import ROOM_GET_CODE, PLAYERS_GET
 
 def create():
     parameters = JSON_BODY(request)
@@ -22,5 +22,11 @@ def create():
     if not room_record:
         return(FAIL(CODE_NOTFOUND))
 
+    players = PLAYERS_GET(room_record)
+
+    for player in players:
+        if player["name"] == user_name:
+            return(FAIL(CODE_CONFLICT))
+
     db.Player.insert(name=user_name, room_id=room_record.id)
     return(200)

modules/http_util.py

 from gluon import *
 
 CODE_MISSING = 400
+CODE_NOTFOUND = 404
 CODE_JSON = 406
+CODE_CONFLICT = 409
 CODE_GONE = 410
 CODE_SEMANTIC = 422
-CODE_NOTFOUND = 404
 
 def FAIL(_code):
     current.response.status = _code

static/css/base.css

+.error {
+    color: red;
+}
+
+
+/* ============== Footer ===================== */
+
 #footer {
     position: fixed;
 

views/default/index.html

@@ -8,6 +8,7 @@
     <form id="form_login">
         <input type="text" id="room_code" placeholder="Room Code" maxlength="4"><br><br>
         <input type="text" id="user_name" placeholder="User Name" maxlength="15"><br><br>
+        <span id="form_login_error" class="error"></span><br>
         <input type="submit" value="Enter">
     </form>
 </div>
@@ -15,8 +16,27 @@
 {{block page_js}}
 <script type="text/javascript">
     $("#form_login").on("submit", function(){
+        $("#form_login_error").html();
         var payload = {"room_code": $("#room_code").val(), "user_name": $("#user_name").val()}
-        AJAX_JSON("{{=URL('player', 'create')}}", payload, function(code, data){alert(code);});
+        AJAX_JSON("{{=URL('player', 'create')}}", payload, function(_code, _data){
+
+            switch(_code){
+                case 200:
+                    break;
+                case 404:
+                    $("#form_login_error").html("Room could not be found.");
+                    break;
+                case 409:
+                    $("#form_login_error").html("Please choose a different user name.");
+                    break;
+                case 422:
+                    $("#form_login_error").html("Please provide valid values.");
+                    break;
+                default:
+                    $("#form_login_error").html("Error");
+            }
+
+        });
         return false;
     });
 </script>