diff --git a/src/services/collections.py b/src/services/collections.py
index fdfce148..c4033ef2 100644
--- a/src/services/collections.py
+++ b/src/services/collections.py
@@ -14,7 +14,7 @@ from datetime import datetime
 class Collection(BaseModel):
     name: str
     description: str
-    elements: List[str]
+    courses: List[str] # course_id
 
 
 class CollectionInDB(Collection):
diff --git a/src/services/courses.py b/src/services/courses.py
index a141e482..efc12b16 100644
--- a/src/services/courses.py
+++ b/src/services/courses.py
@@ -32,6 +32,8 @@ class CourseInDB(Course):
 
 class CourseElement(BaseModel):
     element_id: str
+    content: str
+    content_type: str
     position: int
 
 
@@ -52,6 +54,9 @@ class CourseChapterInDB(CourseChapter):
 
 #### Classes ####################################################
 
+# TODO : Add courses photo & cover upload and delete
+
+
 # Courses
 
 async def get_course(course_id: str, current_user: User):
diff --git a/src/services/houses.py b/src/services/houses.py
index 473b577f..d0be5fea 100644
--- a/src/services/houses.py
+++ b/src/services/houses.py
@@ -26,6 +26,7 @@ class HouseInDB(House):
 
 #### Classes ####################################################
 
+# TODO : Add house photo upload and delete
 
 async def get_house(house_id: str, current_user: User):
     await check_database()
diff --git a/src/services/users.py b/src/services/users.py
index 7296848c..e6d0895d 100644
--- a/src/services/users.py
+++ b/src/services/users.py
@@ -38,6 +38,7 @@ class UserInDB(UserWithPassword):
 #### Classes ####################################################
 
 # TODO : user actions security
+# TODO : avatar upload and update
 
 
 async def get_user(username: str):