> On 27 Jan 2016, at 18:59, Chris Macklin <chris.mack...@gmail.com> wrote: > > If I declare a Sequence at the class level in a model class declaration using > declarative (SQLAlchemy 0.9.10 on postgres), the sequence is not created by > create_all unless the sequence is explicitly associated with a Column. My > use case is a column which stores a URI; if a row is inserted which already > has a URI, it is passed in. If an insert doesn't come with a URI, we need to > mint a new one, and thus call a default function which retrieves the next > value of a sequence that is exclusively used for minting these URIs, and > appends it to a namespace before adding that value to the column. Thus, the > sequence isn't actually associated with a column, but should still be > table-level and created/destroyed when the table is added or dropped. > > All of the workarounds I've found so far are somewhat distasteful: > - creating a dummy table, associating the sequence with a column in that > table, and never inserting into it (not great as the sequence is detached > from the table it is logically associated with, plus the chaff of a totally > meaningless table sitting in my db) > - manually calling create on the sequence with the engine; this doesn't > really work, as all of this code is sitting in a larger framework in which > sqlalchemy is executing and it would require significant alterations to the > framework to pass these sequences all the way out to the top level where > create_all is called. > > Any suggestions? Am I missing something obvious here?
According to: http://docs.sqlalchemy.org/en/rel_1_0/core/defaults.html#sqlalchemy.schema.Sequence.params.metadata “”” Additionally, the appropriate CREATE SEQUENCE/ DROP SEQUENCE DDL commands will be emitted corresponding to this Sequence when MetaData.create_all() andMetaData.drop_all() are invoked. “”” For this to work, the Sequence needs to be attached to the Metadata, which you can access as Base.metadata. Does that make any difference? Simon -- 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 https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
