看起来基本上是这样的：

try:
    # add duplicate,nothing bad happens yet,is only in sqla session
    db.session.add(User(email='already_used_email@address_that_has_to_be_unique.com'))
    # commit,now the IntegrityError is raised,when sqla inserts
    db.session.commit()
except IntegrityError as e:
    db.session.rollback()
    # this is what i do with MysqL,check the exception for code 1062
    # how can i replace this with something db independent?
    code,msg = e.orig
    if code == 1062:
        # send warning
        pass

现在,对于一个,这使得已经无法用例如测试.内存中的sqlite.不好,但我可以忍受.

然而,第二,我可能(必须/希望其他超出此问题的范围)切换到Postgres.当然我可以更改代码(也)检查Postgres错误代码,但我希望有一种方法让sqlALchemy告诉我,重复发生独立于数据库.数据库方言抽象……？