adapt to code comments

Author: MoSchmidt

backend/app/core/database.py

@@ -2,7 +2,6 @@
 
 import logging
 from importlib import import_module
-from typing import Tuple
 
 from sqlalchemy import create_engine, inspect, text
 from sqlalchemy.orm import declarative_base, sessionmaker
@@ -21,53 +20,9 @@
 SESSION_LOCAL = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
 
-def _timestamp_sql(dialect_name: str) -> Tuple[str, str]:
-    """Return dialect-specific SQL fragments for timestamp columns."""
-
-    if dialect_name == "postgresql":
-        return "TIMESTAMPTZ", "NOW()"
-    if dialect_name == "sqlite":
-        return "TIMESTAMP", "CURRENT_TIMESTAMP"
-    return "TIMESTAMP", "CURRENT_TIMESTAMP"
-
-
-def _migrate_legacy_users_table() -> None:
-    """Rename and backfill the legacy ``users`` table if it exists."""
-
-    with engine.begin() as connection:
-        inspector = inspect(connection)
-        existing_tables = set(inspector.get_table_names())
-        if "user" in existing_tables or "users" not in existing_tables:
-            return
-
-        logger.info("🚚 Migrating legacy users table to new schema...")
-        connection.execute(text('ALTER TABLE "users" RENAME TO "user"'))
-
-        inspector = inspect(connection)
-        columns = {column["name"] for column in inspector.get_columns("user")}
-
-        if "id" in columns:
-            connection.execute(text('ALTER TABLE "user" RENAME COLUMN id TO user_id'))
-
-        if "created_at" not in columns:
-            column_type, default_expr = _timestamp_sql(connection.dialect.name)
-            connection.execute(
-                text(
-                    f'ALTER TABLE "user" ADD COLUMN created_at {column_type} DEFAULT {default_expr}'
-                )
-            )
-            connection.execute(
-                text(f'UPDATE "user" SET created_at = {default_expr} WHERE created_at IS NULL')
-            )
-
-        logger.info("✅ Legacy users table migrated.")
-
-
 def init_db() -> None:
     """Automatically create or update tables based on SQLAlchemy models."""
 
-    _migrate_legacy_users_table()
-
     for module in (
             "app.models.user",
             "app.models.project",

backend/app/models/project_paper.py

@@ -14,21 +14,40 @@ class ProjectPaper(Base):
     """Associative entity connecting projects with papers."""
 
     __tablename__ = "project_paper"
-    __table_args__ = (UniqueConstraint("project_id", "paper_id", name="uq_project_paper"),)
 
-    project_paper_id: Mapped[int] = mapped_column(BigInteger, primary_key=True, index=True)
+    # Ensure a paper can only be linked once to the same project.
+    __table_args__ = (
+        UniqueConstraint(
+            "project_id",
+            "paper_id",
+            name="uq_project_paper_project_id_paper_id",
+        ),
+    )
+
+    project_paper_id: Mapped[int] = mapped_column(
+        BigInteger, primary_key=True, index=True
+    )
+
     project_id: Mapped[int] = mapped_column(
         BigInteger, ForeignKey("project.project_id"), nullable=False, index=True
     )
+
     paper_id: Mapped[int] = mapped_column(
         BigInteger, ForeignKey("paper.paper_id"), nullable=False, index=True
     )
+
     added_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), nullable=False, server_default=func.now()
+        DateTime(timezone=True),
+        nullable=False,
+        server_default=func.now(),
     )
 
-    project: Mapped["Project"] = relationship("Project", back_populates="project_papers")
-    paper: Mapped["Paper"] = relationship("Paper", back_populates="project_links")
+    project: Mapped["Project"] = relationship(
+        "Project", back_populates="project_papers"
+    )
+    paper: Mapped["Paper"] = relationship(
+        "Paper", back_populates="project_links"
+    )
 
 
 if TYPE_CHECKING:

backend/app/routes/auth_routes.py

@@ -14,7 +14,7 @@
     status_code=status.HTTP_200_OK,
     summary="Authenticate a user and return JWT tokens"
 )
-def login(request: LoginRequest, db: Session = Depends(get_db)):
+def login(request: LoginRequest, db: Session = Depends(get_db)) -> LoginResponse:
     """Authenticate a user and return access plus refresh tokens."""
 
     user, access_token, refresh_token = AuthService.login(db, request.username)
@@ -32,7 +32,7 @@ def login(request: LoginRequest, db: Session = Depends(get_db)):
     status_code=status.HTTP_200_OK,
     summary="Generate a new access token using a refresh token"
 )
-def refresh_access_token(request: RefreshRequest):
+def refresh_access_token(request: RefreshRequest) -> RefreshResponse:
     """Validate a refresh token and return a new access token."""
 
     new_access_token = AuthService.refresh(request.refresh_token)

backend/app/routes/user_routes.py

@@ -15,7 +15,7 @@
     status_code=status.HTTP_201_CREATED,
     summary="Create a new user"
 )
-def create_user(request: UserCreate, db: Session = Depends(get_db)):
+def create_user(request: UserCreate, db: Session = Depends(get_db)) -> UserResponse:
     """Create a new user."""
 
     user = UserService.create_user(db, request.username)
@@ -31,7 +31,7 @@ def create_user(request: UserCreate, db: Session = Depends(get_db)):
 def get_current_user_profile(
         current_username: str = Depends(get_current_user),
         db: Session = Depends(get_db),
-):
+) -> UserResponse:
     """Return the authenticated user's profile."""
 
     user = UserService.get_user_by_username(db, current_username)