Refactoring file structure, not tested yet

app/db/base.py

@@ -0,0 +1,6 @@
+# app/db/base.py
+
+from sqlalchemy.orm import DeclarativeBase
+
+class Base(DeclarativeBase):
+    pass

app/db/models.py

@@ -0,0 +1,57 @@
+# app/db/models.py
+
+from sqlalchemy import String, Integer, DateTime, func, Index
+from sqlalchemy.orm import Mapped, mapped_column
+from datetime import datetime
+from app.db.base import Base
+
+
+class URL(Base):
+    __tablename__ = "urls"
+
+    id: Mapped[int] = mapped_column(
+        Integer,
+        primary_key=True,
+        index=True
+    )
+
+    short_code: Mapped[str] = mapped_column(
+        String(10),
+        unique=True,
+        nullable=False,
+        index=True
+    )
+
+    original_url: Mapped[str] = mapped_column(
+        String(2048),
+        nullable=False,
+        index=True
+    )
+
+    clicks: Mapped[int] = mapped_column(
+        Integer,
+        default=0,
+        nullable=False
+    )
+
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False
+    )
+
+    last_accessed: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True
+    )
+
+    # Additional compound index for faster lookups
+    __table_args__ = (
+        Index("idx_short_original", "short_code", "original_url"),
+    )
+
+    def __repr__(self) -> str:
+        return (
+            f"<URL(id={self.id}, short_code='{self.short_code}', "
+            f"original_url='{self.original_url}', clicks={self.clicks})>"
+        )

app/db/session.py

@@ -0,0 +1,26 @@
+# app/db/session.py
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+from app.core.config import settings
+
+# Create SQLAlchemy engine
+engine = create_engine(
+    settings.database_url,
+    pool_pre_ping=True,  # helps prevent stale connections
+)
+
+# Session factory
+SessionLocal = sessionmaker(
+    autocommit=False,
+    autoflush=False,
+    bind=engine,
+)
+
+# Dependency for FastAPI
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()