Flask11--Flask-script，sqlalchemy

一.flask-script

用于实现类似于django中 python3 manage.py runserver ...类似的命令

安装：pip3 install flask-script

1.1使用

from flask_script import Manager
app = Flask(__name__)
manager=Manager(app)
...
if __name__ == '__main__':
    manager.run()
#以后在执行，直接：python3 manage.py runserver
#python3 manage.py runserver --help

1.2自定制命令

@manager.command
def custom(arg):
    """
    自定义命令
    python manage.py custom 123
    :param arg:
    :return:
    """
    print(arg)
@manager.option('-n', '--name', dest='name')
#@manager.option('-u', '--url', dest='url')
def cmd(name, url):
    """
    自定义命令（-n也可以写成--name）
    执行： python manage.py  cmd -n lqz -u http://www.oldboyedu.com
    执行： python manage.py  cmd --name lqz --url http://www.oldboyedu.com
    :param name:
    :param url:
    :return:
    """
    print(name, url)
#有什么用？

 

二. SQLAlchemy

1.介绍

SQLAlchemy是一个基于Python实现的ORM框架。该框架建立在 DB API之上，使用关系对象映射进行数据库操作，简言之便是：将类和对象转换成SQL，然后使用数据API执行SQL并获取执行结果。

pip3 install sqlalchemy

组成部分：

Engine，框架的引擎
Connection Pooling ，数据库连接池
Dialect，选择连接数据库的DB API种类
Schema/Types，架构和类型
SQL Exprression Language，SQL表达式语言

SQLAlchemy本身无法操作数据库，其必须以来pymsql等第三方插件，Dialect用于和数据API进行交流，根据配置文件的不同调用不同的数据库API，从而实现对数据库的操作，如：

MySQL-Python
    mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>
    
pymysql
    mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]
    
MySQL-Connector
    mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>
    
cx_Oracle
    oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]
    
更多：http://docs.sqlalchemy.org/en/latest/dialects/index.html

django中如何反向生成models

python manage.py inspectdb > app/models.py

2.简单使用（能创建表，删除表，不能修改表）

修改表：在数据库添加字段，类对应上

1执行原生sql（不常用）

import time
import threading
import sqlalchemy
from sqlalchemy import create_engine
from sqlalchemy.engine.base import Engine

engine = create_engine(
    "mysql+pymysql://root:123456@127.0.0.1:3306/test?charset=utf8",
    max_overflow=0,  # 超过连接池大小外最多创建的连接
    pool_size=5,  # 连接池大小
    pool_timeout=30,  # 池中没有线程最多等待的时间，否则报错
    pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）
)

conn = engine.raw_connection()
cursor = conn.cursor()
cursor.execute("select * from app01_book")
result = cursor.fetchall()
print(result)
cursor.close()
conn.close()

2 orm使用

models.py

import datetime
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index
Base = declarative_base()  #继承的模型  类似于django的Model


class Users(Base):
    __tablename__ = 'users'  # 数据库表名称
    id = Column(Integer, primary_key=True)  # id 主键
    name = Column(String(32), index=True, nullable=False)  # name列，索引，不可为空
    # email = Column(String(32), unique=True)
    # ctime = Column(DateTime, default=datetime.datetime.now)
    # extra = Column(Text, nullable=True)
    __table_args__ = (
        # UniqueConstraint('id', 'name', name='uix_id_name'), #联合唯一
        # Index('ix_id_name', 'name', 'email'), #索引
    )

def init_db():
    """
    根据类创建数据库表
    :return:
    """
    engine = create_engine(
        "mysql+pymysql://root:123456@127.0.0.1:3306/aaa?charset=utf8",
        max_overflow=0,  # 超过连接池大小外最多创建的连接
        pool_size=5,  # 连接池大小
        pool_timeout=30,  # 池中没有线程最多等待的时间，否则报错
        pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）
    )

    Base.metadata.create_all(engine)

    # Base.metadata.drop_all(engine)   显而易见 是删除数据库

if __name__ == '__main__':
    # drop_db()
    init_db()

app.py

from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Users
#"mysql+pymysql://root@127.0.0.1:3306/aaa"
engine = create_engine("mysql+pymysql://root:123456@127.0.0.1:3306/aaa", max_overflow=0, pool_size=5)
Connection = sessionmaker(bind=engine)
# 每次执行数据库操作时，都需要创建一个Connection
con = Connection()
# ############# 执行ORM操作 #############
obj1 = Users(name="lqz")
con.add(obj1)
# 提交事务
con.commit()
# 关闭session，其实是将连接放回连接池
con.close()

3.一对多关系

Copyclass Hobby(Base):
    __tablename__ = 'hobby'
    id = Column(Integer, primary_key=True)
    caption = Column(String(50), default='篮球')


class Person(Base):
    __tablename__ = 'person'
    nid = Column(Integer, primary_key=True)
    name = Column(String(32), index=True, nullable=True)
    # hobby指的是tablename而不是类名，uselist=False
    hobby_id = Column(Integer, ForeignKey("hobby.id"))
    
    # 跟数据库无关，不会新增字段，只用于快速链表操作
    # 类名，backref用于反向查询
    hobby=relationship('Hobby',backref='pers')

4.多对多关系

class Boy2Girl(Base):
    __tablename__ = 'boy2girl'
    id = Column(Integer, primary_key=True, autoincrement=True)
    girl_id = Column(Integer, ForeignKey('girl.id'))
    boy_id = Column(Integer, ForeignKey('boy.id'))


class Girl(Base):
    __tablename__ = 'girl'
    id = Column(Integer, primary_key=True)
    name = Column(String(64), unique=True, nullable=False)

class Boy(Base):
    __tablename__ = 'boy'

    id = Column(Integer, primary_key=True, autoincrement=True)
    hostname = Column(String(64), unique=True, nullable=False)
    
    # 与生成表结构无关，仅用于查询方便,放在哪个单表中都可以
    servers = relationship('Girl', secondary='boy2girl', backref='boys')

5.操作数据表

from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Users
  
engine = create_engine("mysql+pymysql://root:123456@127.0.0.1:3306/aaa", max_overflow=0, pool_size=5)


Session = sessionmaker(bind=engine)
  
# 每次执行数据库操作时，都需要创建一个session
session = Session()
  
# ############# 执行ORM操作 #############
obj1 = Users(name="lqz")
session.add(obj1)
  
# 提交事务
session.commit()
# 关闭session
session.close()

6.基于scoped_session实现线程安全

Copyfrom sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session
from models import Users

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)

"""
# 线程安全，基于本地线程实现每个线程用同一个session
# 特殊的：scoped_session中有原来方法的Session中的一下方法：

public_methods = (
    '__contains__', '__iter__', 'add', 'add_all', 'begin', 'begin_nested',
    'close', 'commit', 'connection', 'delete', 'execute', 'expire',
    'expire_all', 'expunge', 'expunge_all', 'flush', 'get_bind',
    'is_modified', 'bulk_save_objects', 'bulk_insert_mappings',
    'bulk_update_mappings',
    'merge', 'query', 'refresh', 'rollback',
    'scalar'
)
"""
#scoped_session类并没有继承Session,但是却又它的所有方法
session = scoped_session(Session)
# ############# 执行ORM操作 #############
obj1 = Users(name="alex1")
session.add(obj1)

# 提交事务
session.commit()
# 关闭session
session.close()

7.基本增删查改

import time
import threading
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import create_engine
from sqlalchemy.sql import text
from db import Users, Hosts

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)

session = Session()

----------------1.增-----------------

obj1 = Users(name="111")
session.add(obj1)

session.add_all([
    Users(name="111"),
    Users(name="222"),
    Hosts(name="333"),
])
session.commit()
----------------2.删除-----------------
session.query(Users).filter(Users.id > 2).delete()
session.commit()
----------------3.修改-----------------
#传字典
1.  session.query(Users).filter(Users.id > 0).update({"name" : "lqz"})


2.  session.query(Users).filter(Users.id > 0).update({Users.name: Users.name + "099"}, synchronize_session=False)  # 字符串  类似于django的F查询

3.  session.query(Users).filter(Users.id > 0).update({"age": Users.age + 1}, 							synchronize_session="evaluate")   #数字
session.commit()

----------------4.查-----------------

1.r1 = session.query(Users).all()


2. r2 = session.query(Users.name.label('xx'), Users.age).all() #只取age列，把name																重命名为xx
3.#filter传的是表达式，filter_by传的是参数
    r3 = session.query(Users).filter(Users.name == "lqz").all()
    r4 = session.query(Users).filter_by(name='lqz').all()
    r5 = session.query(Users).filter_by(name='lqz').first()

4.#:value 和:name 相当于占位符，用params传参数
    r6 = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name='fred').order_by(Users.id).all()
    
    
 5.#自定义查询sql
r7 = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name='ed').all()


#增，删，改都要commit()
session.close()

8 高级操作

from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import User,Person,Hobby
from sqlalchemy.sql import text
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/aaa", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session=Session()


# 1 查询名字为lqz的所有user对象
# ret = session.query(User).filter_by(name='ccc099').all()
# 2 表达式，and条件连接
# ret = session.query(User).filter(User.id > 1, User.name == 'egon').all()
# 查找id在1和10之间，并且name=egon的对象
# ret = session.query(User).filter(User.id.between(1, 10), User.name == 'egon').all()

# in条件(class_,因为这是关键字，不能直接用)
# ret = session.query(User).filter(User.id.in_([1,3,4])).all()

# 取反 ~
ret = session.query(User).filter(~User.id.in_([1,3,4])).all()

#二次筛选
# select *
# ret = session.query(User).filter(User.id.in_(session.query(User.id).filter_by(name='egon'))).all()
# # select name，id 。。。。
# ret = session.query(User.id,User.name).filter(User.id.in_(session.query(User.id).filter_by(name='egon'))).all()

'''
SELECT users.id AS users_id, users.name AS users_name 
FROM users 
WHERE users.id IN (SELECT users.id AS users_id 
FROM users 
WHERE users.name = %(name_1)s)

'''


#
from sqlalchemy import and_, or_
#or_包裹的都是or条件，and_包裹的都是and条件
#查询id>3并且name=egon的人
# ret = session.query(User).filter(and_(User.id > 3, User.name == 'egon')).all()

# 查询id大于2或者name=ccc099的数据
# ret = session.query(User).filter(or_(User.id > 2, User.name == 'ccc099')).all()
# ret = session.query(User).filter(
#     or_(
#         User.id < 2,
#         and_(User.name == 'egon', User.id > 3),
#         User.extra != ""
#     )).all()
# print(ret)

'''
select *from user where id<2 or (name=egon and id >3) or extra !=''
'''


# 通配符，以e开头，不以e开头
# ret = session.query(User).filter(User.name.like('e%')).all()   
# ret = session.query(User).filter(~User.name.like('e%')).all()
											  like('S_')  匹配一个
    											%	 多个					

# 限制，用于分页，区间 limit
# 前闭后开区间，1能取到，3取不到
ret = session.query(User)[1:3]

'''
select * from users limit 1,2;
'''


# 排序，根据name降序排列（从大到小）
# ret = session.query(User).order_by(User.name.desc()).all()
# ret = session.query(User).order_by(User.name.asc()).all()
#第一个条件降序排序后，再按第二个条件升序排
# ret = session.query(User).order_by(User.id.asc(),User.name.desc()).all()
# ret = session.query(User).order_by(User.name.desc(),User.id.asc()).all()


# 分组
from sqlalchemy.sql import func

# ret = session.query(User).group_by(User.name).all()
#分组之后取最大id，id之和，最小id
# sql 分组之后，要查询的字段只能有分组字段和聚合函数
# ret = session.query(
#     func.max(User.id),
#     func.sum(User.id),
#     func.min(User.id),
#     User.name).group_by(User.name).all()
# '''
# select max(id),sum(id),min(id) from user group by name;
#
# '''
# for obj in ret:
#     print(obj[0],'----',obj[1],'-----',obj[2],'-----',obj[3])
# print(ret)

#haviing筛选
# ret = session.query(
#     func.max(User.id),
#     func.sum(User.id),
#     func.min(User.id)).group_by(User.name).having(func.min(User.id) >2).all()

'''
select max(id),sum(id),min(id) from user group by name having min(id)>2;

'''
print(ret)
session.commit()

session.close()

9.一对多

from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import User,Person,Hobby,Boy,Girl,Boy2Girl
from sqlalchemy.sql import text
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/aaa", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session=Session()

###  1 一对多插入数据
obj=Hobby(caption='足球')
session.add(obj)
p=Person(name='张三',hobby_id=2)
session.add(p)
### 2 方式二(默认情况传对象有问题)
###### Person表中要加 hobby = relationship('Hobby', backref='pers')
p=Person(name='李四',hobby=Hobby(caption='美女'))
等同于
p=Person(name='李四2')
p.hobby=Hobby(caption='美女2')
session.add(p)

## 3 方式三，通过反向操作
hb = Hobby(caption='人妖')
hb.pers = [Person(name='文飞'), Person(name='博雅')]
session.add(hb)


4 查询（查询：基于连表的查询，基于对象的跨表查询）
### 4.1 基于对象的跨表查询(子查询，两次查询)
 正查
p=session.query(Person).filter_by(name='张三').first()
print(p)
print(p.hobby.caption)
# 反查
h=session.query(Hobby).filter_by(caption='人妖').first()
print(h.pers)

### 4.2 基于连表的跨表查（查一次）
默认根据外键连表
isouter=True 左外连，表示Person left join Hobby，没有右连接，反过来即可
# 不写 inner join
person_list=session.query(Person,Hobby).join(Hobby,isouter=True).all()
print(person_list)
print(person_list)
for row in person_list:
print(row[0].name,row[1].caption)

 '''
 select * from person left join hobby on person.hobby_id=hobby.id

'''

ret = session.query(Person, Hobby).filter(Person.hobby_id == Hobby.id)
print(ret)
 '''
 select * from user,hobby where user.id=favor.nid;
 
 '''


#join表，默认是inner join
# ret = session.query(Person).join(Hobby)
# # ret = session.query(Hobby).join(Person,isouter=True)
# '''
# SELECT *
# FROM person INNER JOIN hobby ON hobby.id = person.hobby_id
# '''
# print(ret)


# 指定连表字段（从来没用过）
ret = session.query(Person).join(Hobby,Person.nid==Hobby.id, isouter=True)
ret = session.query(Person).join(Hobby,Person.hobby_id==Hobby.id, isouter=True).all()
# print(ret)
'''
SELECT *
FROM person LEFT OUTER JOIN hobby ON person.nid = hobby.id

'''

# print(ret)

# 组合（了解）UNION 操作符用于合并两个或多个 SELECT 语句的结果集
union和union all的区别？
q1 = session.query(User.name).filter(User.id > 2)  # 6条数据
q2 = session.query(User.name).filter(User.id < 8) # 2条数据


q1 = session.query(User.id,User.name).filter(User.id > 2)  # 6条数据
q2 = session.query(User.id,User.name).filter(User.id < 8) # 2条数据
ret = q1.union_all(q2).all()
ret1 = q1.union(q2).all()
print(ret)
print(ret1)

q1 = session.query(User.name).filter(User.id > 2)
q2 = session.query(Hobby.caption).filter(Hobby.nid < 2)
ret = q1.union_all(q2).all()

10.多对多

# session.add_all([
#     Boy(hostname='霍建华'),
#     Boy(hostname='胡歌'),
#     Girl(name='刘亦菲'),
#     Girl(name='林心如'),
# ])
# session.add_all([
#     Boy2Girl(girl_id=1, boy_id=1),
#     Boy2Girl(girl_id=2, boy_id=1)
# ])


##### 要有girls = relationship('Girl', secondary='boy2girl', backref='boys')
# girl = Girl(name='张娜拉')
# girl.boys = [Boy(hostname='张铁林'),Boy(hostname='费玉清')]
# session.add(girl)

# boy=Boy(hostname='蔡徐坤')
# boy.girls=[Girl(name='谢娜'),Girl(name='巧碧螺')]
# session.add(boy)
# session.commit()


# 基于对象的跨表查

# girl=session.query(Girl).filter_by(id=3).first()
# print(girl.boys)

#### 基于连表的跨表查询

# 查询蔡徐坤约过的所有妹子
'''
select girl.name from girl,boy,Boy2Girl where boy.id=Boy2Girl.boy_id and girl.id=Boy2Girl.girl_id where boy.name='蔡徐坤'

'''
# ret=session.query(Girl.name).filter(Boy.id==Boy2Girl.boy_id,Girl.id==Boy2Girl.girl_id,Boy.hostname=='蔡徐坤').all()

'''
select girl.name from girl inner join Boy2Girl on girl.id=Boy2Girl.girl_id inner join boy on boy.id=Boy2Girl.boy_id where boy.hostname='蔡徐坤'

'''
# ret=session.query(Girl.name).join(Boy2Girl).join(Boy).filter(Boy.hostname=='蔡徐坤').all()
ret=session.query(Girl.name).join(Boy2Girl).join(Boy).filter_by(hostname='蔡徐坤').all()
print(ret)


### 执行原生sql（用的最多的）
### django中orm如何执行原生sql
#
# cursor = session.execute('insert into users(name) values(:value)',params={"value":'xxx'})
# print(cursor.lastrowid)
# session.commit()

session.close()



res = session.squery(User.name.label('xx')).first()
res.xx  #label 相当于起别名

11.其它

import time
import threading

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import create_engine
from sqlalchemy.sql import text, func
from sqlalchemy.engine.result import ResultProxy
from db import Users, Hosts, Hobby, Person, Group, Server, Server2Group

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session = Session()

# 关联子查询:correlate(Group)表示跟Group表做关联，as_scalar相当于对该sql加括号，用于放在后面当子查询
subqry = session.query(func.count(Server.id).label("sid")).filter(Server.id == Group.id).correlate(Group).as_scalar()
result = session.query(Group.name, subqry)
"""
SELECT `group`.name AS group_name, (SELECT count(server.id) AS sid 
FROM server 
WHERE server.id = `group`.id) AS anon_1 
FROM `group`
"""

select id，name,
(select avr(score) from 成绩表 where 成绩表.sid=学生表.id) as x
from 学生表
subqry = session.query(func.count(成绩表.scort).label("sc")).filter(学生表.id == 成绩表.sid).correlate(学生表).as_scalar()
result = session.query(学生表.name, subqry)


session.close()

12.Flask-SQLAlchemy

1 Flask-SQLAlchemy
2 flask-migrate
    -python3 manage.py db init 初始化：只执行一次
    -python3 manage.py db migrate 等同于 makemigartions
    -python3 manage.py db upgrade 等同于migrate
    
3 看代码
4 Flask-SQLAlchemy如何使用
	1 from flask_sqlalchemy import SQLAlchemy
	2 db = SQLAlchemy()
    3 db.init_app(app)
    4 以后在视图函数中使用
    	-db.session 就是咱们讲的session
        
5 flask-migrate的使用（表创建，字段修改）
	1 from flask_migrate import Migrate,MigrateCommand
    2 Migrate(app,db)
	3 manager.add_command('db', MigrateCommand)
6 直接使用
    -python3 manage.py db init 初始化：只执行一次，创建migrations文件夹
    -python3 manage.py db migrate 等同于 makemigartions
    -python3 manage.py db upgrade 等同于migrate