Add run.py for SQL Alchemy 1.6 to 2.0

sqlalchemy_1.6_to_2.0/README.md

@@ -1,12 +1,10 @@
 # SQLAlchemy 1.6 to 2.0 Migration Example
 
-[![Documentation](https://img.shields.io/badge/docs-docs.codegen.com-blue)](https://docs.codegen.com/tutorials/sqlalchemy-1.6-to-2.0)
+This codemod demonstrates how to use Codegen to automatically migrate SQLAlchemy 1.6 code to the new 2.0-style query interface. For a complete walkthrough, check out our [tutorial](https://docs.codegen.com/tutorials/sqlalchemy-1.6-to-2.0).
 
-This example demonstrates how to use Codegen to automatically migrate SQLAlchemy 1.6 code to the new 2.0-style query interface. For a complete walkthrough, check out our [tutorial](https://docs.codegen.com/tutorials/sqlalchemy-1.6-to-2.0).
+## How the Migration Script Works
 
-## What This Example Does
-
-The migration script handles four key transformations:
+The codemod script handles four key transformations:
 
 1. **Convert Query to Select**
    ```python
@@ -18,6 +16,7 @@ The migration script handles four key transformations:
        select(User).where(User.name == 'john')
    ).scalars().all()
    ```
+   This transformation replaces the legacy Query interface with the new Select-based API, providing better type safety and consistency.
 
 2. **Update Session Execution**
    ```python
@@ -29,6 +28,7 @@ The migration script handles four key transformations:
    users = session.execute(select(User)).scalars().all()
    first_user = session.execute(select(User)).scalars().first()
    ```
+   Session execution is updated to use the new execute() method, which provides clearer separation between SQL construction and execution.
 
 3. **Modernize ORM Relationships**
    ```python
@@ -42,6 +42,7 @@ The migration script handles four key transformations:
    class Address(Base):
        user = relationship("User", back_populates="addresses")
    ```
+   Relationships are modernized to use explicit back_populates instead of backref, making bidirectional relationships more maintainable and explicit.
 
 4. **Add Type Annotations**
    ```python
@@ -59,6 +60,7 @@ The migration script handles four key transformations:
        name: Mapped[str] = mapped_column()
        addresses: Mapped[List["Address"]] = relationship()
    ```
+   Type annotations are added using SQLAlchemy 2.0's Mapped[] syntax, enabling better IDE support and runtime type checking.
 
 ## Running the Example
 
@@ -70,13 +72,7 @@ pip install codegen
 python run.py
 ```
 
-The script will process all Python files in the `repo-before` directory and apply the transformations in the correct order.
-
-## Understanding the Code
-
-- `run.py` - The migration script
-- `repo-before/` - Sample SQLAlchemy 1.6 application to migrate
-- `guide.md` - Additional notes and explanations
+The script will process all Python files in the `input_repo` directory and apply the transformations in the correct order.
 
 ## Learn More
 

sqlalchemy_1.6_to_2.0/input_repo/database.py

@@ -3,7 +3,9 @@
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
 
-SQLALCHEMY_DATABASE_URL = "postgresql://user:password@localhost/dbname"  # Change to your database URL
+SQLALCHEMY_DATABASE_URL = (
+    "postgresql://user:password@localhost/dbname"  # Change to your database URL
+)
 
 engine = create_engine(SQLALCHEMY_DATABASE_URL)
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

sqlalchemy_1.6_to_2.0/input_repo/models.py

@@ -1,7 +1,8 @@
-from sqlalchemy import Column, Integer, String, ForeignKey, Index
-from sqlalchemy.orm import relationship, backref
+from sqlalchemy import Column, Integer, String, ForeignKey
+from sqlalchemy.orm import relationship
 from database import Base
 
+
 class Publisher(Base):
     __tablename__ = "publishers"