On 11/30/2015 02:29 PM, Alyssa Kwan wrote: > Thanks Michael, > > These constructs are actually composed of 3 tables - the temporal data > itself, a clock table, and an element clock table - both the clocks keep > track of points in time that exist within time ranges since ranges are > lossy. Does this advice still hold?
yes, don't subclass SchemaItem :) Unless you're building out a Postgresql extension and your own "CREATE" command that you could run with psql (assuming that's not the case). A related requirement is the ability > to autoload via reflection these constructs, for which I've created > tables similar to INFORMATION_SCHEMA.TABLES and > INFORMATION_SCHEMA.COLUMNS. I'm only concerned about operating on > PostgreSQL. > > What's the recommended way to approaching this? > > Thanks, > Alyssa > > On Monday, November 30, 2015 at 10:26:28 AM UTC-8, Michael Bayer wrote: > > > > On 11/30/2015 12:54 PM, Alyssa Kwan wrote: > > Hi, > > > > The problem I'm trying to solve is I've created a multi-temporal > > relational table construct (à la bitemporality) that I want to create > > SQLAlchemy Core composite operations for (and eventually > SQLAlchemy ORM). > > > > Let's call these TemporalRelationSet's. I've subclassed SchemaItem. > > I'd not do that. If the thing you're dealing with is a Table, use > Table. If you want to define a bunch of special operations involving a > certain Table and you're not able to use ORM, make a > TemporalRelationSet > of course, however, this is not a schema item. It would refer to the > Table you're dealing with. That is, prefer composition over > inheritance. A SchemaItem is only intended to be the base of objects > that exist concretely within DDL. > > > > I > > also do registration against a Registry class that I've subclassed > > MetaData for, with a __visit_name__ of 'registry'. The idea is that I > > initialize a Registry, can register Table's against it, as well as > these > > TemporalRelationSet's. > > When your TemporalRelationSet is created, it can put memos inside of > Table.info for its Table object; if you want things to happen when that > Table gets created, you can use the before_create / after_create event > listeners to handle this. > > > > > > Does this make sense for what I'm trying to do? > > > > If so, the specific problem I'm running into is create_all() on > Registry > > doesn't do anything. I started digging into the Visitable > metaclass, but > > hit a wall of understanding. > > Stick to the event API here, see the overview at > > http://docs.sqlalchemy.org/en/latest/core/events.html?highlight=after_create#schema-events > > <http://docs.sqlalchemy.org/en/latest/core/events.html?highlight=after_create#schema-events>. > > > > > > > > > I'm running Python 3.4.3 on OS X El Capitan with SQLAlchemy 1.0.9. > > > > Thanks! > > Alyssa > > > > -- > > 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+...@googlegroups.com <javascript:> > > <mailto:sqlalchemy+unsubscr...@googlegroups.com <javascript:>>. > > To post to this group, send email to sqlal...@googlegroups.com > <javascript:> > > <mailto:sqlal...@googlegroups.com <javascript:>>. > > Visit this group at http://groups.google.com/group/sqlalchemy > <http://groups.google.com/group/sqlalchemy>. > > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. > > -- > 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 > <mailto:sqlalchemy+unsubscr...@googlegroups.com>. > To post to this group, send email to sqlalchemy@googlegroups.com > <mailto:sqlalchemy@googlegroups.com>. > Visit this group at http://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/d/optout. -- 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 post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
