#11 Added enrollment table and relationship between user/couse

backend/app/models.py

@@ -5,6 +5,13 @@ from datetime import datetime
 from werkzeug.security import generate_password_hash, check_password_hash
 
 
+enrollment = db.Table(
+    "enrollment",
+    sa.Column("user_id", sa.ForeignKey("user.id"), primary_key=True),
+    sa.Column("course_id", sa.ForeignKey("course.id"), primary_key=True),
+)
+
+
 class User(UserMixin, db.Model):
     id = sa.Column(sa.Integer, primary_key=True)
     username = sa.Column(sa.String(64), index=True, unique=True)
@@ -13,24 +20,39 @@ class User(UserMixin, db.Model):
     password_hash = sa.Column(sa.String(128))
     last_seen = sa.Column(sa.DateTime, default=datetime.utcnow)
     token = sa.Column(sa.String(32), index=True, unique=True)
+    enrolled_courses = db.relationship(
+        "Course",
+        secondary=enrollment,
+        backref=db.backref("students", lazy="dynamic"),
+        lazy="dynamic",
+    )
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return f"<User {self.username}>"
 
-    def set_password(self, password):
+    def set_password(self, password) -> None:
         self.password_hash = generate_password_hash(password)
 
-    def check_password(self, password):
+    def check_password(self, password) -> bool:
         return check_password_hash(self.password_hash, password)
 
-    def to_dict(self):
+    def is_enrolled(self, c) -> bool:
+        return self.enrolled_courses.filter(enrollment.c.course_id == c.id).count() > 0
+
+    def enroll(self, c) -> bool:
+        if not self.is_enrolled(c):
+            self.enrolled_courses.append(c)
+            return True
+        return False
+
+    def to_dict(self) -> dict:
         return {
             "id": self.id,
             "username": self.username,
             "email": self.email,
         }
 
-    def from_dict(self, data, new_user=False):
+    def from_dict(self, data, new_user=False) -> None:
         for field in ["role", "username", "email"]:
             if field in data:
                 setattr(self, field, data[field])
@@ -45,7 +67,10 @@ class Course(db.Model):
     instructor = sa.Column(sa.ForeignKey(User.id), index=True)
     created_at = sa.Column(sa.DateTime)
 
-    def from_dict(self, data):
+    def __repr__(self) -> str:
+        return f"<Course {self.name}>"
+
+    def from_dict(self, data) -> None:
         for field in ["name", "description", "instructor"]:
             if field in data:
                 setattr(self, field, data[field])
@@ -53,7 +78,7 @@ class Course(db.Model):
         if not self.created_at:
             self.created_at = datetime.now()
 
-    def to_dict(self):
+    def to_dict(self) -> dict:
         d = {}
         for f in ["id", "name", "description", "instructor", "created_at"]:
             d[f] = getattr(self, f)