比较SQLlalchemy Core中的两个UUID

Question

我正在使用sqlalchemy 1.2

简而言之，产生错误的是：

uuidvar = uuid4()
mytable.select().where(mytable.c.uuidColumn == uuidvar) #where mytable is of type sqlalchemy.Table 

错误：

  File "/Users/remi/PycharmProjects/my_venv/lib/python3.6/site-packages/sqlalchemy/dialects/postgresql/psycopg2.py", line 448, in process
    value = _python_UUID(value)
  File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/uuid.py", line 137, in __init__
    hex = hex.replace('urn:', '').replace('uuid:', '')
sqlalchemy.exc.StatementError: (builtins.AttributeError) 'UUID' object has no attribute 'replace' [SQL: 'SELECT col1, col2, col3 FROM myTable nWHERE uuidColumn = '%(uuidColumn_1)s']

有这样的表格：

CREATE TABLE myTable (
  uuidColumn uuid primary key default uuid_generate_v4()
  col1 text,
  col2 text,
  col3 text
)

和 Python 中的表生成：

metadata = MetaData(engine=db) # db is created by "create_engine", nothing fancy
myTable = Table('myTable', metadata, autoload=True)

Answer 1

我也有类似的问题。要解决此错误，您需要使用 as_uuid=True 定义 uuidColumn。这样：

from sqlalchemy.dialects import postgresql
uuidColumn = db.Column(postgresql.UUID(as_uuid=True))

有关更多详细信息，请参阅迈克尔·拜耳的评论：https://bitbucket.org/zzzeek/sqlalchemy/issues/3323/in-099-uuid-columns-are-broken-with