MappingError: Class 'YourClass' is not mapped

When working with an Object-Relational Mapping (ORM) tool like SQLAlchemy in Python, encountering a MappingError stating that a particular class is not mapped can be frustrating.

Understanding the Issue
The error message might look something like this:

sqlalchemy.orm.exc.MappingError: Class 'YourClass' is not mapped

This indicates that SQLAlchemy is unable to locate a mapping for the specified class.

Potential Causes and Solutions

1. Check Class Inheritance: Ensure that your class inherits from db.Model or the appropriate base class used for SQLAlchemy models.
2. Import Statements: Confirm that your class is imported where needed. If your class definition is in a separate module, make sure you import it correctly in the module where you're working with the database.
3. Bind Metadata to Database: SQLAlchemy relies on metadata to map classes to database tables. Ensure that the metadata is bound to the database engine.
4. Check Database Initialization: Ensure that you initialize the database before working with models. This typically involves calling db.create_all().

Conclusion
A MappingError indicating that a class is not mapped is often a result of misconfigurations or oversights in the class definition, import statements, or metadata binding