db_pool.py
from DBUtils.PooledDB import PooledDB
import pymysql
POOL = PooledDB(
creator=pymysql, # 使用链接数据库的模块
maxconnections=6, # 连接池允许的最大连接数，0和None表示不限制连接数
mincached=2, # 初始化时，链接池中至少创建的空闲的链接，0表示不创建
maxcached=5, # 链接池中最多闲置的链接，0和None不限制
maxshared=3,
# 链接池中最多共享的链接数量，0和None表示全部共享。
# PS: 无用，因为pymysql和MySQLdb等模块的 threadsafety都为1，所有值无论设置为多少，_maxcached永远为0，所以永远是所有链接都共享。
blocking=True, # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
maxusage=None, # 一个链接最多被重复使用的次数，None表示无限制
setsession=[], # 开始会话前执行的命令列表。如：["set datestyle to ...", "set time zone ..."]
ping=0,
# ping MySQL服务端，检查是否服务可用。
# 如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always
host=‘127.0.0.1‘,
port=3306,
user=‘root‘,
password=‘123‘,
database=‘db2‘,
charset=‘utf8‘,
autocommit=‘True‘
)
mysql_singleton.py
import pymysql
from orm_pool import db_pool
class Mysql(object):
def __init__(self):
self.conn = db_pool.POOL.connection()
self.cursor = self.conn.cursor(pymysql.cursors.DictCursor)
def close(self):
self.cursor.close()
self.conn.close()
def select(self,sql,args=None):
self.cursor.execute(sql,args)
res = self.cursor.fetchall() # 列表套字典
return res
def execute(self,sql,args):
try:
self.cursor.execute(sql,args)
except BaseException as e :
print(e)
orm.py
from orm_singleton.mysql_singleton import Mysql
# 定义字段类
class Field(object):
def __init__(self, name, column_type, primary_key, default):
self.name = name
self.column_type = column_type
self.primary_key = primary_key
self.default = default
# 定义具体的字段
class StringField(Field):
def __init__(self, name, column_type=‘varchar(255)‘, primary_key=False, default=None):
super().__init__(name, column_type, primary_key, default)
class IntegerField(Field):
def __init__(self, name, column_type=‘int‘, primary_key=False, default=None):
super().__init__(name, column_type, primary_key, default)
class ModelMetaClass(type):
def __new__(cls, class_name, class_bases, class_attrs):
# 我仅仅只想拦截模型表的类的创建过程
if class_name == ‘Models‘:
return type.__new__(cls, class_name, class_bases, class_attrs)
# 给类放表名,主键字段,所有字段
table_name = class_attrs.get(‘table_name‘, class_name)
# 定义一个存储主键的变量
primary_key = None
# 定义一个字典用来存储用户自定义的表示表的所有字段信息
mappings = {}
# for循环当前类的名称空间
for k, v in class_attrs.items():
if isinstance(v, Field):
mappings[k] = v
if v.primary_key:
if primary_key:
raise TypeError("主键只能有一个")
primary_key = v.name
# 将重复的键值对删除
for k in mappings.keys():
class_attrs.pop(k)
if not primary_key:
raise TypeError(‘必须要有一个主键‘)
# 将处理好的数据放入class_attrs中
class_attrs[‘table_name‘] = table_name
class_attrs[‘primary_key‘] = primary_key
class_attrs[‘mappings‘] = mappings
return type.__new__(cls, class_name, class_bases, class_attrs)
class Models(dict, metaclass=ModelMetaClass):
def __init__(self, **kwargs):
super().__init__(**kwargs)
def __getattr__(self, item):
return self.get(item, ‘没有该键值对‘)
def __setattr__(self, key, value):
self[key] = value
# 查询方法
@classmethod
def select(cls, **kwargs):
ms = Mysql()
# select * from userinfo
if not kwargs:
sql = ‘select * from %s‘ % cls.table_name
res = ms.select(sql)
else:
# select * from userinfo where id = 1
k = list(kwargs.keys())[0]
v = kwargs.get(k)
sql = ‘select * from %s where %s=?‘ % (cls.table_name, k)
# select * from userinfo where id = ?
sql = sql.replace(‘?‘, ‘%s‘) # select * from userinfo where id = %s
res = ms.select(sql,v)
if res:
return [ cls(**r) for r in res] # 将数据库的一条数据映射成类的对象
# 新增方法
def save(self):
ms = Mysql()
# insert into userinfo(name,password) values(‘jason‘,‘123‘)
# insert into %s(%s) values(?)
fields = [] # [name,password]
values = []
args = []
for k,v in self.mappings.items():
if not v.primary_key: # 将id字段去除 因为新增一条数据 id是自动递增的不需要你传
fields.append(v.name)
args.append(‘?‘)
values.append(getattr(self,v.name))
# insert into userinfo(name,password) values(?,?)
sql = "insert into %s(%s) values(%s)"%(self.table_name,‘,‘.join(fields),‘,‘.join(args))
# insert into userinfo(name,password) values(?,?)
sql = sql.replace(‘?‘,‘%s‘)
ms.execute(sql,values)
# 修改方法:基于已经存在了的数据进行一个修改操作
def update(self):
ms = Mysql()
# update userinfo set name=‘jason‘,password=‘123‘ where id = 1
fields = [] # [name,password]
values = []
pr = None
for k,v in self.mappings.items():
if v.primary_key:
pr = getattr(self,v.name,v.default)
else:
fields.append(v.name+‘=?‘)
values.append(getattr(self,v.name,v.default))
sql = ‘update %s set %s where %s = %s‘%(self.table_name,‘,‘.join(fields),self.primary_key,pr)
# update userinfo set name=‘?‘,password=‘?‘ where id = 1
sql = sql.replace(‘?‘,‘%s‘)
ms.execute(sql,values)
if __name__ == ‘__main__‘:
class Teacher(Models):
table_name = ‘teacher‘
tid = IntegerField(name=‘tid‘,primary_key=True)
tname = StringField(name=‘tname‘)
# obj = Teacher(tname=‘jason老师‘)
# obj.save()
# res = Teacher.select()
# for r in res:
# print(r.tname)
# print(res)
res = Teacher.select(tid=1)
teacher_obj = res[0]
teacher_obj.tname = ‘jason老师‘
teacher_obj.update()
res1 = Teacher.select()
print(res1)
# class User(Models):
# table_name = ‘User‘
# id = IntegerField(name=‘id‘, primary_key=True)
# name = StringField(name=‘name‘)
# password = StringField(name=‘password‘)
# print(User.primary_key)
# print(User.mappings)
# obj = User(name=‘jason‘)
# print(obj.table_name)
# print(obj.primary_key)
# print(obj.mappings)
原文地址：https://www.cnblogs.com/HZLS/p/11073535.html
时间： 2024-08-14 01:35:54