您可以使用SQLalchemy反射API。

为了获得唯一约束，请发出get_unique_constraints。

主键是唯一的，因此您也必须发出get_pk_constraint。

创建的表：

CREATE TABLE user (    id INTEGER NOT NULL,     name VARCHAr(255),     email VARCHAr(255),     login VARCHAr(255),     PRIMARY KEY (id),     UNIQUE (email),     UNIQUE (login))

例：

from sqlalchemy import create_enginefrom sqlalchemy.engine.reflection import Inspector# engine = create_engine(...)insp = Inspector.from_engine(engine)print "PK: %r" % insp.get_pk_constraint("user")print "UNIQUE: %r" % insp.get_unique_constraints("user")

输出：

PK: {'name': None, 'constrained_columns': [u'login']}UNIQUE: [{'column_names': [u'email'], 'name': None}, {'column_names': [u'login'], 'name': None}]

您可以通过以下方式验证唯一约束：

pk = insp.get_pk_constraint("user")['constrained_columns']unique = map(lambda x: x['column_names'], insp.get_unique_constraints("user"))for column in ['name', 'id', 'email', 'login']:    print "Column %r has an unique constraint: %s" %(column, [column] in [pk]+unique)

输出：

Column 'name' has an unique constraint: FalseColumn 'id' has an unique constraint: TrueColumn 'email' has an unique constraint: TrueColumn 'login' has an unique constraint: True

更新01

如果您想在创建表之前更简单地检查列，则上面的代码仅检查已创建表的列约束：

from sqlalchemy import create_engine, Column, typesfrom sqlalchemy.ext.declarative import declarative_basefrom sqlalchemy.orm import sessionmaker, scoped_sessionbase = declarative_base()class User(base):    __tablename__ = "user"    id = Column(types.Integer, primary_key=True)    name = Column(types.String(255))    email = Column(types.String(255), unique=True)    login = Column(types.String(255), unique=True)# do not create any table#engine = create_engine('sqlite:///:memory:', echo=True)#session = scoped_session(sessionmaker(bind=engine))#base.metadata.create_all(engine)# check if column is (any) a primary_key or has unique constraint# Note1: You can use User.__table__.c too, it is a alias to columns# Note2: If you don't want to use __table__, you could use the reflection API like:#        >>> from sqlalchemy.inspection import inspect#        >>> columns = inspect(User).columnsresult = dict([(c.name, any([c.primary_key, c.unique])) for c in User.__table__.columns])print(result)

输出：

{'email': True, 'login': True, 'id': True, 'name': False}

如果只想检查一些列，则只能执行以下操作：

for column_name in ['name', 'id', 'email', 'login']:    c = User.__table__.columns.get(column_name)    print("Column %r has an unique constraint: %s" %(column_name, any([c.primary_key, c.unique])))

输出：

Column 'name' has an unique constraint: FalseColumn 'id' has an unique constraint: TrueColumn 'email' has an unique constraint: TrueColumn 'login' has an unique constraint: True