SQLAlchemy内省 [英] SQLAlchemy introspection

问题描述

我想做的是从SqlAlchemy实体定义中获取Column()的所有内容，确定它们的类型和约束，以便能够进行预验证，转换数据并向用户显示自定义表单.

What I am trying to do is to get from SqlAlchemy entity definition all it's Column()'s, determine their types and constraints, to be able to pre-validate, convert data and display custom forms to user.

如何进行内省?

示例:

class Person(Base):
    '''
        Represents Person
    '''
    __tablename__ = 'person'

    # Columns
    id = Column(String(8), primary_key=True, default=uid_gen)
    title = Column(String(512), nullable=False)
    birth_date = Column(DateTime, nullable=False)

我想获取此ID，标题，出生日期，确定其限制(例如标题为字符串，最大长度为512或birth_date为datetime等)

I want to get this id, title, birth date, determine their restrictions (such as title is string and max length is 512 or birth_date is datetime etc)

谢谢

推荐答案

如果使用的是sqlalchemy 0.8，则应签出新功能

If you are using sqlalchemy 0.8, then you should check out the new feature New Class Inspection System. Sample code extract from the documentation:

class User(Base):
    __tablename__ = 'user'

    id = Column(Integer, primary_key=True)
    name = Column(String)
    name_syn = synonym(name)
    addresses = relationship(Address)

# universal entry point is inspect()
>>> b = inspect(User)

# column collection
>>> b.columns
[<id column>, <name column>]

否则，请参见访问表和列文档的一部分.同样，从文档中提取代码:

Otherwise, see Accessing Tables and Columns part of the documentation. Again, code extract from the docu:

employees = Table(...)
# or if using declarative
#employees = Employee.__table__

# or just
employees.c.employee_id

# via string
employees.c['employee_id']

# iterate through all columns
for c in employees.c:
    print c

# access a column's name, type, nullable, primary key, foreign key
employees.c.employee_id.name
employees.c.employee_id.type
employees.c.employee_id.nullable
employees.c.employee_id.primary_key
employees.c.employee_dept.foreign_keys

这篇关于SQLAlchemy内省的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！