even google is not telling me which vendor has produced this expression. Because "computed by" is the most generic phrase.
I see a brief mention in firebird's docs ? no clue. I'd probably use @compiles on top of CreateTable for this, and use a regular expression to tokenize out the columns that have "computed_by" in their info field. To really support extensions like this fully we'd have to break out compiler to make usage of a CreateColumn directive, then you'd be able to put @compiles on top of CreateColumn and generate the columns directly. wouldn't be too terrible but 0.8 is quite backlogged (see http://www.sqlalchemy.org/trac/ticket/2463). Or why not do it at the type level ? Can you just make a UserDefinedType here ? 2463 might be nicer. On Apr 9, 2012, at 1:36 PM, Werner wrote: > Is there a way in SA 0.7.6 to define computed columns as part of other > DeclarativeBase columns? > > Currently I do manual DDL, but would like to get things setup to be able to > easier move to another db backend. > > Most of my computed columns are calculations like the one on AVAILCAPACITY > below, but also have a few simple selects like in the USEDCAPACITY column. > > CREATE TABLE WINERACKIT ( > WINERACKITID PKEYS NOT NULL, > SPLIT INTEGER NOT NULL, > CAPACITY INTEGER DEFAULT 0, > FK_WINERACKBID PKEYS NOT NULL /* PKEYS = BIGINT */, > USEDCAPACITY COMPUTED BY ((SELECT COUNT(BOTTAG.TAGNO) FROM BOTTAG WHERE > BOTTAG.FK_WINERACKIT_ID = WINERACKIT.ID)), > AVAILCAPACITY COMPUTED BY (CAPACITY-USEDCAPACITY) > > Thanks in advance for some pointers on how to do this. > > Werner > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalchemy@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
