sqlalchemy: la inserción masiva de alambique falla: el objeto ‘str’ no tiene atributo ‘_autoincrement_column’

Mi modelo se parece a

class Category(UserMixin, db.Model): __tablename__ = 'categories' uuid = Column('uuid', GUID(), default=uuid.uuid4, primary_key=True, unique=True) name = Column('name', String, nullable=False) parent = Column('parent', String, nullable=False) created_on = Column('created_on', sa.types.DateTime(timezone=True), default=datetime.utcnow()) __table_args__ = (UniqueConstraint('name', 'parent'),) def __init__(self, name, parent): self.name = name self.parent = parent def __repr__(self): return '' % ( self.uuid, self.name, self.category_type) 

donde GUID es un tipo sqlalchemy personalizado, creo la tabla utilizando la opción alembic --autogenerate

  op.create_table('categories', sa.Column('uuid', UUID(), nullable=False), sa.Column('name', sa.String(), nullable=False), sa.Column('parent', sa.String(), nullable=False), sa.Column('created_on', sa.DateTime(timezone=True), nullable=True), sa.PrimaryKeyConstraint('uuid'), sa.UniqueConstraint('name', 'parent'), sa.UniqueConstraint('uuid') ) 

y la tabla de PostgreSQL como

  Table "public.categories" Column | Type | Modifiers ------------+--------------------------+----------- uuid | uuid | not null name | character varying | not null parent | character varying | not null created_on | timestamp with time zone | Indexes: "categories_pkey" PRIMARY KEY, btree (uuid) "categories_name_parent_key" UNIQUE CONSTRAINT, btree (name, parent) 

Intento ejecutar la revisión y actualizar la base de datos como

 def upgrade(): op.bulk_insert('categories', [ {'name': 'first', 'parent': 'first_parent'}, {'name': 'second', 'parent': 'second_parent'} ] ) 

Cuando ejecuto un alembic upgrade head , veo el error como

  File "/Users/me/.virtualenvs/envs/project/lib/python2.7/site-packages/alembic/environment.py", line 494, in run_migrations self.get_context().run_migrations(**kw) File "/Users/me/.virtualenvs/envs/project/lib/python2.7/site-packages/alembic/migration.py", line 211, in run_migrations change(**kw) File "alembic/versions/491d4f91e0bc_generate_categories_.py", line 21, in upgrade {'name': 'second', 'parent': 'second_parent'} File "", line 7, in bulk_insert File "/Users/me/.virtualenvs/envs/project/lib/python2.7/site-packages/alembic/operations.py", line 710, in bulk_insert self.impl.bulk_insert(table, rows) File "/Users/me/.virtualenvs/envs/project/lib/python2.7/site-packages/alembic/ddl/impl.py", line 179, in bulk_insert table._autoincrement_column = None AttributeError: 'str' object has no attribute '_autoincrement_column' 

¿Qué es lo que estoy haciendo mal aquí?

todo lo que tenía que hacer es crear una table antes de bulk_insert, incluso si tengo un esquema explícito en models.py separados.py

 import sqlalchemy as sa from sqlalchemy.sql import table from alembic import op def upgrade(): categories = table('categories', sa.Column('uuid', UUID(), primary_key=True, unique=True, autoincrement=False), sa.Column('name', String), sa.Column('parent', String), sa.Column('created_on', sa.types.DateTime(timezone=True), default=datetime.utcnow()) ) op.bulk_insert(categories, [ {'name': 'first', 'parent': 'first_parent'}, {'name': 'second', 'parent': 'second_parent'} ] ) 

y luego pude ejecutar un alembic upgrade head sin problemas y los datos se serializaron correctamente en la base de datos.