the async aspect here is not that important, for Declarative + reflection you likely should look at DeferredReflection: https://docs.sqlalchemy.org/en/14/orm/declarative_tables.html#using-deferredreflection
for async, where it has in the example: Reflected.prepare(engine) you would instead say: await async_connection.run_sync(Reflected.prepare) On Wednesday, December 14, 2022 at 8:43:45 AM UTC-5 dcs3spp wrote: > Hi, > > I am using alembic to apply a migration for a postgresql view using an *async > *engine. > I can see this successfully applied in the database. > > I have the following declarative mapped class to the view, defined as: > > > > > > *class MailingListView(Base): """View for mailing labels. After > metata reflection from db -> model expecting columns to be available on > this class. """* > * __tablename__ = "mailing_list_view"* > > > > * # Specify the column override from the underlying view that is the > primary key id = Column(UUID(as_uuid=True), primary_key=True) * > > > > > > > > > > * # Expecting these columns below to be mapped in this class after > # metadata reflection. Currently have to uncomment these # to manually > synchronise with view! # # addressee = Column(String) # street = > Column(String) # town = Column(String) # county = Column(String) # > postcode = Column(String) # cursor = Column(String)* > > I am reflecting the views using the following: > > > > > > > > > * def use_inspector(conn): inspector = inspect(conn) > return inspector.get_view_names() views = await > connection.run_sync(use_inspector) # I can see the table columns in > __table__.c.keys() # after the reflection below has run* > * await connection.run_sync(* > * target_metadata.reflect,* > * only=views,* > * views=True,* > * extend_existing=True,* > * )* > > After performing the above reflection I can see that my mapped model has > the underlyingtable columns updated with those defined in the underlying > view. > > > > *obj = MailingListView()obj.__table__.c.keys()* > However, the properties of my mapped class are not updated after > reflection, raising an exception: > > > > *obj = MailingListView()obj.town = "town" # this raises an exception with > unavailable property* > How is it possible for a postgresql db (asyncpg) + async sqlalchemy to: > > Synchronise the columns of a declarative model with its underlying table > after metadata reflection. Currently, I have to manually specify the > columns in the declarative model. > > > -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/6cb2e213-02a3-4d9f-921f-ec6886ad68ecn%40googlegroups.com.
