• Table of contents
• Introduction
• How the storage layer works
• Storage model concepts
• Model classes with ndb
• Oppia's datastore interface
• The GAE datastore interface implementation
• Model classes at Oppia
• Naming conventions and structure
• Model versioning
• Deletion policy for wipeout
• Takeout policy
• Export data
• Map property names to takeout keys
• Has reference to user ID
• Apply deletion policy
• Pseudonymizable models
• Common procedures
• Create a new model class
• Add a pseudonymizable model
• Modify a model field
• Add an index to a field
• Remove an old field from a model
• Contact