import pymysql
from pymysql.cursors import DictCursor
# class Field:
# def __init__(self,name,column =None,chief=False,unique=False,index=False,nullable=True, default = None):
# self.name = name
# if column is None:
# self.column = name
# else :
# self.column = column
# self.chief = chief
# self.unique = unique
# self.index = index
# self.nullable = nullable
# self. default = default
#
# def validate(self,value):
# raise NotImplementedError
#
# def __get__(self,instance,owner):
# if instance is None:
# return self
# return instance.__dict__[self.name]
#
# def __set__(self,instance,value):
# self.validate(value)
# instance.__dict__[self.name] = value
#
# def __str__(self):
# return ‘ <{} <{}>> ‘ .format(self.__class__.__name__,self.name)
#
# __repr__ = __str__
#
# class IntField(Field):
# def __init__(self,name,column =None,chief=False,unique=False,index=False,nullable=True, default = None,
# auto_increment = False):
# super(IntField,self).__init__(name,column,chief,unique,index,nullable, default )
# self.auto_increment = auto_increment
#
# def validate(self,value):
# if value is None:
# if self.chief:
# raise TypeError( ‘ {} is primary key,yet value is None ‘ .format(self.name))
# if not self.nullable:
# raise TypeError( ‘ {} required ‘ .format(self.name))
# else :
# if not isinstance(value, int ):
# raise GeneratorExit( ‘ {} should be integer ‘ .format(value))
#
# class StringField(Field):
# def __init__(self,name,column =None,chief=None,unique=None,index=None,nullable=True, default =None,length= None):
# super(StringField,self).__init__(name,column,chief,unique,index,nullable, default )
# self.length = length
#
# def validate(self,value):
# if value is None:
# if self.chief:
# raise TypeError( ‘ {} is primary key,yet value is None ‘ .format(self.name))
# if not self.nullable:
# raise TypeError( ‘ {} required ‘ .format(self.name))
# else :
# if not isinstance(value, str):
# raise GeneratorExit( ‘ {} should be str ‘ .format(value))
# if len(value) > self.length:
# raise ValueError( ‘ {} too long ‘ .format(value))
#
# class S:
# id =IntField( ‘ id ‘ , ‘ id ‘ ,True,nullable=False,auto_increment= True)
# name =StringField( ‘ name ‘ ,nullable=False,length= 64 )
# age =IntField( ‘ age ‘ )
#
# def __init__(self,id,name,age):
# self.id = id
# self.name = name
# self.age = age
#
# def __str__(self):
# return ‘ S({} {} {}) ‘ .format(self.id,self.name,self.age)
#
# __repr__ = __str__
#
# def save(self,conn:pymysql.connections.Connection):
# sql = ‘ insert into s (id,name,age) values (%s,%s,%s) ‘
# cursor =conn.cursor(cursor= DictCursor)
# cursor.execute(sql,args = (self.id,self.name,self.age))
# cursor.close()
class Field:
def __init__(self, name =None, column=None, chief=False, unique=False, index=False, nullable=True, default = None):
self.name = name
if column is None:
self.column = name
else :
self.column = column
self.chief = chief
self.unique = unique
self.index = index
self.nullable = nullable
self. default = default
def validate(self, value):
raise NotImplementedError()
def __get__(self, instance, owner):
if instance is None:
return self
return instance.__dict__[self.name]
def __set__(self, instance, value):
self.validate(value)
instance.__dict__[self.name] = value
def __str__(self):
return ‘ <{} {}> ‘ .format(self.__class__.__name__, self.name)
__repr__ = __str__
class IntField(Field, object ):
def __init__(self, name =None, column=None, chief=False, unique=False, index=False, nullable=True, default = None,
auto_increment = False):
self.auto_increment = auto_increment
super(IntField, self).__init__(name, column, chief, unique, index, nullable, default )
def validate(self, value):
if value is None:
if self.chief:
raise TypeError( ‘ {} is primary key,yet value is None ‘ .format(self.name))
if not self.nullable:
raise TypeError( ‘ {} required ‘ .format(self.name))
else :
if not isinstance(value, int ):
raise GeneratorExit( ‘ {} should be integer ‘ .format(value))
class StringField(Field):
def __init__(self, length, name =None, column=None, chief=False, unique=False, index=False, nullable= True,
default = None, ):
self.length = length
super(StringField, self).__init__(name, column, chief, unique, index, nullable, default )
def validate(self, value):
if value is None:
if self.chief:
raise TypeError( ‘ {} is primary key,yet value is None ‘ .format(self.name))
if not self.nullable:
raise TypeError( ‘ {} required ‘ .format(self.name))
else :
if not isinstance(value, str):
raise GeneratorExit( ‘ {} should be str ‘ .format(value))
if len(value) > self.length:
raise ValueError( ‘ {} too long ‘ .format(value))
class Session:
def __init__(self, conn: pymysql.connections.Connection):
self.conn = conn
self.cursor = None
self.mark = False
def execute(self, sql, *args, ** kwargs):
if self.cursor is None:
self.mark = True
self.cursor = self.conn.cursor(cursor= DictCursor)
if args:
self.cursor.execute(sql, args)
if kwargs:
self.cursor.execute(sql, args = kwargs)
if self.mark:
self.conn.commit()
self.mark = False
def __enter__(self):
self.cursor = self.conn.cursor(cursor= DictCursor)
return self # 以后调用session对象的execute
def __exit__(self, exc_type, exc_value, exc_tb):
self.cursor.close()
print(exc_type, exc_value, exc_tb)
if exc_type:
self.conn.rollback()
else :
self.conn.commit()
# class Session:
# def __init__(self, conn: pymysql.connections.Connection):
# self.conn = conn
#
# def execute(self, sql, *args, ** kwargs):
# try :
# cursor = self.conn.cursor(cursor= DictCursor)
# with cursor:
# if args:
# cursor.execute(sql, args)
# if kwargs:
# cursor.execute(sql, kwargs)
# except:
# self.conn.rollback()
# else :
# self.conn.commit()
class ModelMeta(type):
def __new__(cls, what: str, bases, attrs: dict):
# print(what,bases,attrs)
if attrs. get ( ‘ __tablename__ ‘ , None) is None:
# if ‘ __tablename__ ‘ not in attrs.keys():
attrs.setdefault( ‘ __tablename__ ‘ , what.lower())
mapping = {}
primary_key = []
for k, v in attrs.items():
if isinstance(v, (Field,)):
if v.name is None:
v.name = k # descriptor
if v.column is None:
v.column = k
mapping[k] = v
if v.chief:
primary_key.append(v)
attrs.setdefault( ‘ __mapping__ ‘ , mapping)
attrs.setdefault( ‘ __primary_key__ ‘ , primary_key)
return super(ModelMeta, cls).__new__(cls, what, bases, attrs) # 需要return,否则Model为None
class Model(metaclass= ModelMeta):
def save(self, session: Session):
names = []
columns = []
values = []
for k, v in type(self).__dict__.items(): # 遍历self实例字典,v是值,而type(self)字典为描述器,借助描述器得到column
if isinstance(v, (Field,)):
if k in self.__dict__.keys():
names.append(k)
columns.append(v.column)
values.append(self.__dict__[k])
print(names, columns, values)
sql = ‘ insert into {} ({}) values ({}) ‘ .format(
self.__tablename__,
‘ , ‘ .join(columns),
‘ , ‘ .join([ ‘ %s ‘ ] * len(columns))
)
with session:
session.execute(sql, * values)
class S(Model):
__tablename__ = ‘ pp ‘
id = IntField( ‘ id ‘ , column= ‘ id ‘ , chief=True, nullable=False, auto_increment= True)
sname = StringField( 64 , ‘ sname ‘ , column= ‘ name ‘ , nullable= False)
age = IntField( ‘ age ‘ , chief= True)
def __init__(self, id, name, age):
self.id = id
self.sname = name
self.age = age
def __str__(self):
return ‘ Student({},{},{}) ‘ .format(self.id, self.sname, self.age)
__repr__ = __str__
# def save(self, conn: pymysql.connections.Connection):
# sql = ‘ insert into pp (id,name,age) values (%(id)s,%(name)s,%(age)s) ‘
# try :
# cursor = conn.cursor(cursor= DictCursor)
# with cursor:
# cursor.execute(sql, args ={ ‘ id ‘ : self.id, ‘ name ‘ : self.name, ‘ age ‘ : self.age})
# conn.commit()
# except:
# conn.rollback()
#
# def save(self, session: Session):
# sql = ‘ insert into pp (id,name,age) values (%(id)s,%(name)s,%(age)s) ‘
# session.execute(sql, id =self.id, name=self.name, age= self.age)
# # with session:
# # session.execute(sql,id =self.id,name=self.name,age= self.age)
#
# def save(self, session: Session):
# sql = ‘ insert into pp (id,age,name) values (%(id)s,%(age)s,%(name)s) ‘
# session.execute(sql, name =self.name, age=self.age, id= self.id)
class Engine:
def __init__(self, *args,** kwargs):
self.conn =pymysql.connect(*args,** kwargs)
def save(self,instance:S):
names = []
columns = []
values = []
for k,v in instance.__mapping__.items():
if k in instance.__dict__.keys():
names.append( ‘ `{}` ‘ .format(k))
columns.append( ‘ `{}` ‘ .format(v.column))
values.append(instance.__dict__[k])
query = ‘ insert into {} ({}) values ({}) ‘ .format(
instance.__tablename__,
‘ , ‘ .join(columns),
‘ , ‘ .join([ ‘ %s ‘ ]* len(columns))
)
try :
cursor =self.conn.cursor(cursor= DictCursor)
with cursor:
cursor.execute(query,args = values)
except Exception as e:
print(e.args,e.__context__)
self.conn.rollback()
else :
self.conn.commit()
conn = pymysql.connections.Connection( ‘ localhost ‘ , ‘ root ‘ , ‘ cruces ‘ , ‘ uranus ‘ )
s = S( 444 , ‘ zxc ‘ , 88 )
print(s.id, s.sname, s.age)
# s.save(Session(conn))
print(s.__dict__)
print(S.__dict__)
engine =Engine( ‘ localhost ‘ , ‘ root ‘ , ‘ cruces ‘ , ‘ uranus ‘ )
engine.save(s)
# for k,v in S.__dict__.items():
# # print(v,v.__class__.__bases__,type(v.__class__))
# if v.__class__.__bases__[ 0 ] == Field:
# print(k)
import sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column,Integer,String,Float,Enum,Date
Base = declarative_base()
class Student(Base):
__tablename__ = ‘ Stu ‘
id =Column(Integer,primary_key=True,nullable=False,autoincrement= True)
name =Column(String( 64 ),nullable= False)
age =Column(Float,unique= True)
def __repr__(self):
return ‘ <{} id:{}, name:{}, age:{}> ‘ .format(self.__class__.__name__,self.id,self.name,self.age)
__str__ = __repr__
engine =sqlalchemy.create_engine( " mysql+pymysql://root:cruces@localhost:3306/uranus " ,echo= True)
Base.metadata.create_all(engine)
ORM框架实现 & sqlalchemy
标签：erro class rom style ada prim exce auto ISE
查看更多关于ORM框架实现 & sqlalchemy的详细内容...
声明：本文来自网络，不代表【好得很程序员自学网】立场，转载请注明出处：http://www.haodehen.cn/did118131