diff --git a/WebApi/Model/Answer.cs b/WebApi/Model/Answer.cs
index 6e10e70..e3705b8 100644
--- a/WebApi/Model/Answer.cs
+++ b/WebApi/Model/Answer.cs
@@ -9,14 +9,12 @@ namespace Model
     ///     id : identifier in the database
     ///     content : content of the answer
     ///     idQuestion : the id of the question which it answer to
-    ///     question : the question which it answer to
     /// </summary>
     public class Answer
     {
         private uint id;
         private string? content;
-        private uint idQuestion;
-        public Question? question;
+        private uint? idQuestion;
 
         //      getters and setters for attributes
         public uint Id
@@ -29,28 +27,23 @@ namespace Model
             get => content == null ? "" : content;
             set { content = value == "" ? null : value; }
         }
-        public uint IdQuestion
+        public uint? IdQuestion
         {
             get => idQuestion; // null = no idQuestion
-            private set { idQuestion = value; }
+            set { idQuestion = value; }
         }
 
-        public Question? Question
-        {
-            get => question;
-            private set { question = value; IdQuestion = value == null ? 0 : value.Id; }
-        }
         /// <summary>
         /// constructor of an answer
         /// </summary>
         /// <param name="content">the content of the answer</param>
+        /// <param name="idQuestion">the id of the question which it answer to</param>
         /// <param name="id">the id in the database</param>
-        /// <param name="question">the question which it answer to</param>
-        public Answer(string content, Question? question = null, uint id = 0)
+        public Answer(string content, uint? idQuestion = null, uint id = 0)
         {
             Content = content;
+            IdQuestion = idQuestion;
             Id = id;
-            Question = question;
         }
 
     }
diff --git a/WebApi/Model/Lobby.cs b/WebApi/Model/Lobby.cs
index c475cd6..b399a18 100644
--- a/WebApi/Model/Lobby.cs
+++ b/WebApi/Model/Lobby.cs
@@ -15,7 +15,6 @@ namespace Model
     ///     name : name of the lobby
     ///     password : password require to access at the lobby
     ///     idCreator : identifier of the creator player
-    ///     creator : the creator player
     /// </summary>
     public class Lobby
     {
@@ -24,7 +23,6 @@ namespace Model
         private string? password;
         private uint nbPlayers;
         private uint? idCreator;
-        private Player creator;
         //      getters and setters of attributes
         public uint Id
         {
@@ -51,11 +49,6 @@ namespace Model
             get => idCreator;
             private set { idCreator = value; }
         }
-        public Player Creator
-        {
-            get => creator;
-            set { creator = value; idCreator = value.Id; }
-        }
 
         /// <summary>
         /// constructor of a lobby
@@ -63,12 +56,12 @@ namespace Model
         /// <param name="name">the name of the lobby</param>
         /// <param name="creator">the creator</param>
         /// <param name="password">the password require to access to the lobby</param>
-        /// <param name="nbPlayer">the number of players in the lobby</param>
+        /// <param name="nbPlayers">the number of players in the lobby</param>
         /// <param name="id">the id of the lobby</param>
-        public Lobby(string name, Player creator, string password = "", uint nbPlayers = 0, uint id = 0)
+        public Lobby(string name, uint? idCreator, string password = "", uint nbPlayers = 0, uint id = 0)
         {
             Name = name;
-            Creator = creator;
+            IdCreator = idCreator;
             Password = password;
             NbPlayers = nbPlayers;
             Id = id;
diff --git a/WebApi/Model/Question.cs b/WebApi/Model/Question.cs
index cec0bec..c84c4c6 100644
--- a/WebApi/Model/Question.cs
+++ b/WebApi/Model/Question.cs
@@ -17,8 +17,6 @@ namespace Model
     ///     nbFails : number of time that people fail on this question
     ///     idChapter : identifier of the chapter of the question
     ///     idAnswerGood : identifier of the right answer to this question
-    ///     chapter : the chapter of the question
-    ///     answerGood : the right answer to this question
     /// </summary>
     public class Question
     {
@@ -27,9 +25,7 @@ namespace Model
         private byte difficulty;
         private uint nbFalls;
         private uint idChapter;
-        private uint idAnswerGood;
-        private Chapter? chapter;
-        private Answer? answerGood;
+        private uint? idAnswerGood;
 
         public uint Id
         {
@@ -56,32 +52,20 @@ namespace Model
             get => idChapter;
             private set { idChapter = value; }
         }
-        public uint IdAnswerGood
+        public uint? IdAnswerGood
         {
             get => idAnswerGood;
             set { idAnswerGood = value; }
         }
 
-        public Chapter? Chapter
-        {
-            get => chapter;
-            set { chapter = value; IdChapter = value == null ? 0 : value.Id; }
-        }
-
-        public Answer? AnswerGood
-        {
-            get => answerGood;
-            set { answerGood = value; IdAnswerGood = value == null ? 0 : value.Id; }
-        }
-
-        public Question(string content, Chapter? chapter = null, uint id = 0, Answer? answerGood = null)
+        public Question(string content, uint idChapter, uint id = 0, uint? idAnswerGood = null)
         {
             Id = id;
             Content = content;
             Difficulty = 1;
             NbFalls = 0;
-            Chapter = chapter;
-            AnswerGood = answerGood;
+            IdChapter = idChapter;
+            IdAnswerGood = idAnswerGood;
         }
     }
 }