diff --git a/src/api_data/account_export_api.rs b/src/api_data/account_export_api.rs
index 2fd47fe..fee458a 100644
--- a/src/api_data/account_export_api.rs
+++ b/src/api_data/account_export_api.rs
@@ -8,6 +8,7 @@ use serde::Serialize;
 use crate::api_data::comment_api::CommentAPI;
 use crate::api_data::conversation_api::ConversationAPI;
 use crate::api_data::conversation_message_api::ConversationMessageAPI;
+use crate::api_data::entities_constructor::EntitiesConstructor;
 use crate::api_data::friend_api::FriendAPI;
 use crate::api_data::group_api::GroupApi;
 use crate::api_data::movie_api::MovieAPI;
diff --git a/src/api_data/entities_constructor.rs b/src/api_data/entities_constructor.rs
new file mode 100644
index 0000000..ac92df6
--- /dev/null
+++ b/src/api_data/entities_constructor.rs
@@ -0,0 +1,16 @@
+//! # Entities constructor
+//!
+//! This trait simplify the construction of new items
+
+pub trait EntitiesConstructor {
+    type Item;
+
+    /// Turn a server item into an API entry
+    fn new(i: &Self::Item) -> Self;
+
+    /// Parse a list of it
+    fn for_list(l: &Vec<Self::Item>) -> Vec<Self>
+        where Self: std::marker::Sized {
+        l.iter().map(Self::new).collect()
+    }
+}
\ No newline at end of file
diff --git a/src/api_data/mod.rs b/src/api_data/mod.rs
index 4d25b0c..fc7039d 100644
--- a/src/api_data/mod.rs
+++ b/src/api_data/mod.rs
@@ -49,4 +49,5 @@ pub mod res_get_security_questions;
 pub mod res_check_security_answers;
 pub mod account_export_api;
 pub mod user_like_api;
-pub mod survey_response_api;
\ No newline at end of file
+pub mod survey_response_api;
+pub mod entities_constructor;
\ No newline at end of file
diff --git a/src/api_data/survey_response_api.rs b/src/api_data/survey_response_api.rs
index 930eb9c..abd1fc6 100644
--- a/src/api_data/survey_response_api.rs
+++ b/src/api_data/survey_response_api.rs
@@ -3,6 +3,7 @@
 //! @author Pierre Hubert
 use serde::Serialize;
 
+use crate::api_data::entities_constructor::EntitiesConstructor;
 use crate::data::survey_response::SurveyResponse;
 
 #[derive(Serialize)]
@@ -15,8 +16,10 @@ pub struct SurveyResponseAPI {
     choiceID: u64,
 }
 
-impl SurveyResponseAPI {
-    pub fn new(r: &SurveyResponse) -> SurveyResponseAPI {
+impl EntitiesConstructor for SurveyResponseAPI {
+    type Item = SurveyResponse;
+
+    fn new(r: &Self::Item) -> Self {
         SurveyResponseAPI {
             id: r.id,
             time_sent: r.time_sent,
@@ -25,8 +28,4 @@ impl SurveyResponseAPI {
             choiceID: r.choice_id,
         }
     }
-
-    pub fn for_list(l: &Vec<SurveyResponse>) -> Vec<Self> {
-        l.iter().map(Self::new).collect()
-    }
 }
\ No newline at end of file