feat: add mapper for student and it loads

backend/adapters/orm.py

@@ -1,9 +1,12 @@
-from sqlalchemy import Column, MetaData, String, Table
+from sqlalchemy import Column, ForeignKey, MetaData, String, Table
-from sqlalchemy.orm import mapper
+from sqlalchemy.orm import backref, registry, relationship
 
+from backend.model.assessment import Assessment
+from backend.model.student import Student
 from backend.model.tribe import Tribe
 
 metadata = MetaData()
+mapper_registry = registry()
 
 tribes_table = Table(
     "tribes",
@@ -12,6 +15,35 @@ tribes_table = Table(
     Column("level", String(255)),
 )
 
+assessments_table = Table(
+    "assessments",
+    metadata,
+    Column("id", String(255), primary_key=True),
+    Column("name", String(255)),
+    Column("tribe_name", String(255), ForeignKey("tribes.name")),
+)
+
+students_table = Table(
+    "students",
+    metadata,
+    Column("id", String(255), primary_key=True),
+    Column("name", String(255)),
+    Column("tribe_name", String(255), ForeignKey("tribes.name")),
+)
+
 
 def start_mappers():
-    tribes_mapper = mapper(Tribe, tribes_table)
+    tribes_mapper = mapper_registry.map_imperatively(
+        Tribe,
+        tribes_table,
+        properties={
+            "students": relationship(
+                Student, backref="tribes", order_by=students_table.c.id
+            ),
+            "assessments": relationship(
+                Assessment, backref="tribes", order_by=assessments_table.c.id
+            ),
+        },
+    )
+    students_mapper = mapper_registry.map_imperatively(Student, students_table)
+    assessments_mapper = mapper_registry.map_imperatively(Assessment, assessments_table)

backend/model/student.py

@@ -20,3 +20,6 @@ class Student:
         if isinstance(other, Student):
             return self.id == other.id
         return False
+
+    def __hash__(self) -> int:
+        return hash(self.id)

backend/model/tribe.py

@@ -26,8 +26,5 @@ class Tribe:
             return self.name == other.name
         return False
 
-    def __repr__(self) -> str:
-        return f"<Tribe {self.name=}>"
-
     def to_dict(self) -> dict:
         return {"name": self.name, "level": self.level}

tests/integration/test_orm.py

@@ -1,4 +1,5 @@
 from backend.adapters.orm import metadata, start_mappers
+from backend.model.student import Student
 from backend.model.tribe import Tribe
 
 
@@ -40,3 +41,25 @@ def test_tribe_mapper_can_save_and_load_tribe(session):
     session.commit()
 
     assert session.query(Tribe).all() == [tribe]
+
+
+def test_students_mapper_can_load_student(session):
+    session.execute("INSERT INTO tribes (name, level) VALUES " "('tribe1', '2nd')")
+
+    session.execute(
+        "INSERT INTO students (id, name, tribe_name) VALUES "
+        "('1', 'student1', 'tribe1'),"
+        "('2', 'student2', 'tribe1')"
+    )
+
+    tribe = session.query(Tribe).one()
+    expected = [
+        (Student("1", "student1", tribe)),
+        (Student("2", "student2", tribe)),
+    ]
+
+    with session.no_autoflush:
+        students = session.query(Student).all()
+
+    assert set(tribe.students) == set(expected)
+    assert students == expected