On Wed, Apr 25, 2018 at 3:04 PM, Stanislav Lobanov <n10101...@gmail.com> wrote: > Hello! > > I have a base model class with "id" field, which is primary key and also not > nullable. It does not have autoincrement feature, but uses custom sequence > manually to assign it's value. > > There are standard on table / sequence naming: > > class Base: > id = Column(Integer, primary_key=True, nullable=False)
> > > class A(Base): > __tablename__ = 'a' > to use Declarative with common attributes, you need to use either an __abstract__ base class or a mixin, and then you need to extend from declarative_base(). This is probably what you're doing, but since that is not shown I have to make sure this is known; see http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html > > class B(Base): > __tablename__ = 'b' > > > > What i need is to do two things: > > 1. Automatically add sequences to A and B tables (in ORM context, mappers), > named "__tablename__$seq" -> 'a$seq' and 'b$seq'. By sequences i mean an > attribute of type Sequence. > 2. Somehow associate it with "id" column, so the sequence can be > automatically created after "create_all()" function call. > > I tried to use this approach: Associating a Sequence as the Server Side > Default > (http://docs.sqlalchemy.org/en/latest/core/defaults.html#associating-a-sequence-as-the-server-side-default) > but did not succeed because sequence name is always hardcoded in base class, > but in my case it must be autogenerated based on custom naming rule. whether or not you add the sequence as a server side default isn't that important, but setting up the Sequence for the column is most easily achieved by having it inline with the column: Column(Integer, Sequence("foo_seq")) then to create the name dynamically, you need to use declared_attr, again this is in http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html#mixing-in-columns: class Base(Base): __abstract__ = True @declared_attr def id(cls): return Column( Integer, Sequence("%s_seq" % cls.__tablename__), primary_key=True, nullable=False) if you want to add server_default that would also be within the given id() method. > > I have spent four hours trying different techniques but did not succeed with > this. > > Thanks! > > -- > 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 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. -- 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 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.
