That particular idea is a convenience but is never necessary to get a multiple-level inheritance model to work. You simply have the polymorphic_on in the base-most table be the place where the discriminator is stored, and each descendant class defines its discriminator value fully.
On Thu, Aug 22, 2019, at 10:39 AM, Javier Martínez wrote: > In deed I am trying to follow this idea: > https://groups.google.com/d/msg/sqlalchemy/ij10zJ4hOv8/5YQDDkwJ2wUJ > > On Thursday, August 22, 2019 at 3:28:34 PM UTC+2, Javier Martínez wrote: >> Hi everyone, >> >> here again to look for some advice and wise suggestions. >> >> I am facing a situation that I thought I have already covered, but during >> the testing phase (with real data) was not the case. So I have the >> relationship between entities that you can see in the diagram below. I have >> started using the next hierarchy: >> >> Base ->Page->(Tag and Product)-> (TravelPass and Travel) -> (Event, >> Privatebooking) >> >> In each one of this extends I have used the 'polymorphic_on' to work with a >> Joined Inheritance format. So reading more carefully the docs I realized >> that this is not possible and in deed I had problems when querying the >> TravelPass entity getting the results of >> the Travel entity. So right now I am looking for alternatives to implement >> this but I am a bit lost. I think the single table format will not solve it. >> I am thinking about using regular relationships for making it works, but so >> far no great >> ideas come to my mind. I would like to ask for your advice in this topic. >> Thanks in advance. >> >> >> Screenshot 2019-08-22 at 15.16.39.png > > -- > 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/143c780c-2e3a-4634-84fb-537363f95051%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/143c780c-2e3a-4634-84fb-537363f95051%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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/3233e42d-0374-4ca7-a442-7e456831d86c%40www.fastmail.com.
