1. There are a py file in front of a = __all__ [ ' '], indicates that the py file can only export this class *, use: If a py file has a lot of things, a lot of class, you just want to let people import a class I used __all__
when 2.flask SQLAlchemy query, which is equivalent to label as, that is for another name.
filter_by pass parameter, filter expression transfer
r3 = session.query(Users).filter(Users.name == “alex”).all()
r4 = session.query(Users).filter_by(name=‘alex’).all()
It refers to a non ~ Users this condition
ret = session.query(Users).filter(Users.id.in_([1,3,4])).all()
ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()
Mysql wildcard% accounted for many of the characters, underscore _ accounting for a character
ret = session.query(Users).filter(Users.name.like(‘e%’)).all()
ret = session.query(Users).filter(~Users.name.like(‘e%’)).all()
If you do packet filtering for conditions after group_by, having to use
ret = session.query(
func.max(Users.id),
func.sum(Users.id),
func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()
The default table is even join inner join, isouter is true for the external connection, join default conditions inside the outside through the associated key.
ret = session.query(Person).join(Favor, isouter=True).all()
Added in one portion to a plurality of objects in the session, using add_all ()
session.add_all ([
Hobby (Caption = 'ping-pong'),
Hobby (Caption = 'badminton'),
the Person (name = 'John Doe', hobby_id =. 3),
the Person (name = 'John Doe', hobby_id = 4 ),
])
git
On-line system developed after the problem can roll back to the previous version
flask_script
Custom commands, write scripts. Such as for Python manager.py the runserver or Python manager.py the runserver -H -p
(. 1) first from flask_script Import Manager
(2) Register Manager Manager = Manager (App)
(. 3)
if __name__ == '__main__':
manager.run()
manager.py as follows:
from flask import Flask
from flask_script import Manager
app = Flask(__name__)
manager = Manager(app)
@manager.command
def custom(arg):
"""
自定义命令，自定义脚本，相当于位置参数
python manager.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 相当于关键字参数
python manager.py cmd -n zhangweijian -u http://www.baidu.com
:param arg:
:return:
"""
print(name,url)
@app.route('/')
def hello_world():
return 'Hello World!'
if __name__ == '__main__':
manager.run()
flask_migrate database migration
Named database migration
python manager.py db init
python manager.py db migrate
python manager.py db upgrade
(1) first from the Migrate flask_migrate Import, MigrateCommand
(2) register the migrate the migrate = the Migrate (App)
(. 3) manager.add_command ( 'DB', MigrateCommand)
each database has a table is alembic_version, is submitted record table. Recorded in the corresponding folder inside migration