将SQL命令转换为Python的ORM

Question

如何将以下代码转换为Python的ORM，例如SQLalchemy？

＃1将数据放入Pg

import os, pg, sys, re, psycopg2                                                       

#conn = psycopg2.connect("dbname='tkk' host='localhost' port='5432' user='noa' password='123'")

conn = psycopg2.connect("dbname=tk user=naa password=123")
cur = conn.cursor()
cur.execute("""INSERT INTO courses (course_nro)
            VALUES ( %(course_nro)s )""", dict(course_nro='abcd'))
conn.commit()

＃2获取

cur.execute("SELECT * FROM courses")
print cur.fetchall()

有关SQLalchemy

中两个命令的示例

插入

sqlalchemy.sql.expression.insert(table, values=None, inline=False, **kwargs)

选择

sqlalchemy.sql.expression.select(columns=None, whereclause=None, from_obj=[], **kwargs)

Answer 1

在初始声明之后，您可以执行以下操作：

o = Course(course_nro='abcd')
session.add(o)
session.commit()

和

print session.query(Course).all()

声明可能如下所示：

from sqlalchemy import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import session_maker

# create an engine, and a base class
engine = create_engine('postgre://naa:123@localhost/tk')
DeclarativeBase = declarative_base(bind=engine)
metadata = DeclarativeBase.metadata

# create a session
Session = session_maker(engine)
session = Session()

# declare the models
class Cource(DelcarativeBase):
    __tablename__ = 'courses'

    course_nro = Column('course_nro', CHAR(12))

这种声明方法只是使用sqlalchemy的一种方法。

Answer 2

即使这是旧的，更多的例子不会伤害，对吧？我以为我会用PyORMish演示如何做到这一点。

from pyormish import Model

class Course(Model):
    _TABLE_NAME = 'courses'
    _PRIMARY_FIELD = 'id' # or whatever your primary field is
    _SELECT_FIELDS = ('id','course_nro')
    _COMMIT_FIELDS = ('course_nro',)

Model.db_config = dict(
    DB_TYPE='postgres',
    DB_CONN_STRING='postgre://naa:123@localhost/tk'
)

创建：

new_course = Course().create(course_nro='abcd')

选择：

# return the first row WHERE course_nro='abcd'
new_course = Course().get_by_fields(course_nro='abcd')