does anyone know how history mapper works in python?

Question

does anyone know how history mapper works in python? Why are NOT all fields of the main table written to the history table?

example:

class TableNameOrm(DbNameMetaBase, MixinLocked, MixinCreatedAt, Versioned):
    __tablename__ = 'table_name'
    id = Column(Integer, primary_key=True, autoincrement=True)
    title = Column(String(80), nullable=False)
    image_type_code = Column(String(100), nullable=True)  
TableNameHistoryOrm = TableNameOrm.__history_mapper__.class\_

when you update table TableNameOrm, all fields except image_type_code are written to history table TableNameHistoryOrm, it writes null. What should I do so that image_type_code is also updated in the history?

Answer 1

In short, the project had routers to another project, which updated the history table by events