无法呈现 <class 'sqlalchemy.dialects.postgresql.base.UUID'> 类型的元素

Question

我在 Flask-common 的第 57 行看到了这段代码：

id = db.Column(UUID, default=lambda: str(uuid.uuid4()), primary_key=True)

所以我想尝试一下并在我的应用程序 models.py 中使用它（因为我更喜欢 uuid 类型作为我的 ID）

from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy
from sqlalchemy.dialects.postgresql import UUID
import uuid

from app import db

class CostCenter(db.Model):
    __tablename__ = "costcenter"

    id = db.Column('id', UUID(as_uuid=True), default=lambda: str(uuid.uuid4()), primary_key=True)
    name = db.Column('name', db.Text)

    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return '<id {}>'.format(self.id)

但是当我尝试运行 python manage.py db upgrade 时，它导致错误：

  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/compiler.py", line 190, in __init__                                                          
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/compiler.py", line 213, in process                                                           
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/visitors.py", line 81, in _compiler_dispatch                                                 
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/compiler.py", line 2164, in visit_create_table                                               
  File "build/bdist.linux-x86_64/egg/sqlalchemy/util/compat.py", line 199, in raise_from_cause                                                   
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/compiler.py", line 2153, in visit_create_table                                               
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/compiler.py", line 213, in process                                                           
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/visitors.py", line 81, in _compiler_dispatch                                                 
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/compiler.py", line 2184, in visit_create_column                                              
  File "build/bdist.linux-x86_64/egg/sqlalchemy/dialects/sqlite/base.py", line 847, in get_column_specification                                  
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/compiler.py", line 261, in process                                                           
  File "build/bdist.linux-x86_64/egg/sqlalchemy/sql/visitors.py", line 79, in _compiler_dispatch                                                 
sqlalchemy.exc.CompileError: (in table 'costcenter', column 'id'): Compiler <sqlalchemy.dialects.sqlite.base.SQLiteTypeCompiler object at 0x7fc16
c1f1a50> can't render element of type <class 'sqlalchemy.dialects.postgresql.base.UUID'>

为什么它不能呈现 UUID 类型？它在 SQLAlchemy 中可以识别，但为什么在 Flask-SQLAlchemy 中不能识别？

Answer 1

您可以使用 UUID 以防万一使用 postgresql 数据库。

Answer 2

您的列定义使用了一个仅适用于 postgresql 的函数，并且您的数据库类型是 sqlite。

你需要这个：

id = db.Column('id', db.Text(length=36), default=lambda: str(uuid.uuid4()), primary_key=True)

无法呈现 <class 'sqlalchemy.dialects.postgresql.base.UUID'> 类型的元素

can't render element of type <class 'sqlalchemy.dialects.postgresql.base.UUID'>

python

postgresql

sqlalchemy

flask

flask-sqlalchemy