By virtual we mean that we don't have the 'type' column in the DB at all. We determine it runtime via scope from the query.
Here is an example https://gist.github.com/gudata/7ff43e3b6600408b1c1e multi_table_inheritance <https://www.google.com/url?q=https%3A%2F%2Fgithub.com%2Fninjudd%2Fmulti_table_inheritance&sa=D&sntz=1&usg=AFQjCNEOoIsa4h8OtebcAb119NEEy0wPAw> is very old and probably is not addressing the same problem. On Tuesday, June 10, 2014 11:59:54 AM UTC+3, Xavier Noria wrote: > > On Mon, Jun 9, 2014 at 3:00 PM, Ivailo Bardarov <i.bar...@gmail.com > <javascript:>> wrote: > > I have a case when I want to use postgres table inheritance. I want my >> STI inheritance_column to be virtual. What is the reason to check >> for inheritance_column in the columns_hash? >> >> >> https://github.com/rails/rails/blob/4-2-release_notes/activerecord/lib/active_record/inheritance.rb#L151 >> >> If we check only in the record (from the query result), then it would be >> possible to have STI based on virtual columns. >> > > Virtual in what sense? > > AR assumes the type column exists in some queries. For example if you have > > Square < Polygon < AR::Base > > then Square.count triggers > > SELECT COUNT(*) FROM "polygons" WHERE "polygons"."type" IN ('Square') > > Can you make that work with your table definitions? > > I have never used table inheritance in Postgres, but my understanding is > that that kind of logic is builtin. I mean, if I understand it correctly > > SELECT COUNT(*) FROM "squares"; > > would count squares and all their descendants. You need to pass ONLY to > opt-out. > > My first impression (modulus, again, I have not used it) is that Postgres > table inheritance is fundamentally incompatible with STI, and could maybe > deserve its own plugin. I have seen > > https://github.com/ninjudd/multi_table_inheritance > > but does not seem to have much activity. > > > -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-core+unsubscr...@googlegroups.com. To post to this group, send email to rubyonrails-core@googlegroups.com. Visit this group at http://groups.google.com/group/rubyonrails-core. For more options, visit https://groups.google.com/d/optout.
