set default None for user_module_prefix

[allmonday]

fix #1235
fix KeyError of prefix = autogen_context.opts["user_module_prefix"] in render.py

Description

I've made a small snippet to generate create_table ops for my models

def create_orm_migration(metadata):

    operations = []
    for table in metadata.tables.values():
        if table.name.startswith('meeting_note'):
            operations.append(
                ops.CreateTableOp.from_table(table)
            )
            for idx in table.indexes:
                operations.append(ops.CreateIndexOp.from_index(idx))

    print(autogenerate.render_python_code(
        ops.UpgradeOps(ops=operations),
        ), 
    )

and it raises KeyError because UUID is defined in other modules.

from portal.utils.db import UUID

Base = declarative_base()

class MeetingNotes(Base, CommonFieldsMixin):
    __tablename__ = 'meeting_note_notes'

    id = Column(UUID, primary_key=True, default=uuid.uuid1)
    date = Column(Date)
    duration = Column(Integer)
    category = Column(String(1024))
    type = Column(String())
    host_employee_number = Column(Integer)
    content = Column(Text(100000))
    title = Column(String(1024))
    agenda = Column(Text())

this happens in autogenerate.render:_user_autogenerate_prefix, first I attempt to change

prefix = autogen_context.opts["user_module_prefix"]
# to
prefix = autogen_context.opts.get("user_module_prefix")

after I review code around, I guess this is designed to use [] instead of .get(), so I follow the code style and add the default argument user_module_prefix into autogenerate.api:render_python_code

Checklist

This pull request is:

• A documentation / typographical error fix
  • Good to go, no issue or tests are needed
• A short code fix
  • please include the issue number, and create an issue if none exists, which
    must include a complete example of the issue. one line code fixes without an
    issue and demonstration will not be accepted.
  • Please include: Fixes: #<issue number> in the commit message
  • please include tests. one line code fixes without tests will not be accepted.
• A new feature implementation
  • please include the issue number, and create an issue if none exists, which must
    include a complete example of how the feature would look.
  • Please include: Fixes: #<issue number> in the commit message
  • please include tests.

Have a nice day!

[CaselIT]

Hi,

Thanks for the PR. Can you also open an issue so we can properly create a changelog?

Thanks!

[allmonday]

Hi，
linked with #1235 ~

[sqla-tester]

OK, this is sqla-tester setting up my work on behalf of CaselIT to try to get revision 6fa3bc1 of this pull request into gerrit so we can run tests and reviews and stuff

[sqla-tester]

New Gerrit review created for change 6fa3bc1: https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/4609

[sqla-tester]

Gerrit review https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/4609 has been merged. Congratulations! :)