SQLAlchemy:
1. Since the choice method is not provided in sqlalchemy, the choice method provided by the SQLAlchemy-Utils component is used.
from sqlalchemy_utils import ChoiceType
Base = declarative_base()
class Xuan(Base):
__tablename__ = 'xuan'
types_choices = (
(1,'Europe and America'),
(2, 'Japan and South Korea'),
(3,'Old Boy'),
)
id = Column(Integer,primary_key=True,autoincrement=True)
name = Column(String(64))
types = Column(ChoiceType(types_choices,Integer()))
__table_args__ = {
'mysql_engine':'Innodb',
'mysql_charset':'utf8',
}
2.scoped_session:
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session
SessionFactory = sessionmaker(bind=engine)
# Method 1: Since the thread sharing function cannot be provided, all attention should be paid to creating a session in each thread during development.
# from sqlalchemy.orm.session import Session
# Own operation database: 'close', 'commit', 'connection', 'delete', 'execute', 'expire',.....
session = SessionFactory()
# print ('primitive session', session)
# operate
session.close()
# Method 2: Support thread safety, create a session for each thread
# - threading.Local
# - Uniquely identifies
# ScopedSession object
# self.registry(), add parentheses to create a session
# self.registry(), add parentheses to create a session
# self.registry(), add parentheses to create a session
from greenlet import getcurrent as get_ident
session = scoped_session(SessionFactory,get_ident)
# session.add
# operate
session.remove()
3.Flask-SQLAlchemy Flask-Migrate
Flask-SQLAlchemy: Bringing Flask and SQLAlchemy together, the glue
in the __init__.py file
1 Introduce SQLAlchemy in Flask-SQLAlchemy and instantiate a SQLAlchemy object
2 Register Flask-SQLAlchemy:
- There are two ways
Method 1: In the function, SQLAlchemy(app) #If you want to use this method in other places, it is not easy to use
Method 2: Globally:
db = SQLAlchemy(),
In the function db.init_app(app) #Call the init_app method and put the app in it
3. Import the class of models
4. The imported class inherits db.model, but in fact it inherits the Base class in essence
5. manage.py creates database tables, which can be created by commands. Do it with the help of the Flask-Migrate component
Flask-Migrate：
- The old 5 was killed: import db in manage.py, then execute db.create_all() to create a table, and then execute drop_all() to delete the table
This is not good, we can combine it with Flask-Migrate to use
-新5：Flask-Migrate
- Install components: pip install Flask-Migrate
- 5.1 Import
from flask_migrate import Migrate, MigrateCommand
from app import db, app
- 5.2 migrate = Migrate(app,db) #Create an instance
- 5.3 Create command
manager.add_command("db",MigrateCommand)
- 5.4 Execute command
python manage.py db init #Execute only the first time
python manage.py db migrate
python manage.py db upgrade
Before executing the command, he has to connect to the database first, and he will know where the table is placed.
from flask_sqlalchemy import SQLAlchemy
from flask import FLask
db = SQLAlchemy()
def create_app():
app = Flask(__name__)
db.init_app(app)
return app
All used components
Flask
Two operations to connect to the database
or DBUtils: for executing native SQL
Use the sqlhelper in your own util to complete
or SQLAlchemy: follow his own syntax for chaining
Method 1: SQLAlchemy (app) This method has limitations. What if I have to use it elsewhere? Can it be written globally?
Method 2: Advantages,
Instantiate it: db = SQLAlchemy()
register:
Configure the database connection method in settings
SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root:[email protected]:3306/s6?charset=utf8"
SQLALCHEMY_POOL_SIZE = 2
SQLALCHEMY_POOL_TIMEOUT = 30
SQLALCHEMY_POOL_RECYCLE = -1
Flask-SQLAlchemy： db.init_app(app)
Flask-Session #Used to save the session elsewhere
Flask-Script #Generate command
Flask-Migrate #Database migration
Flask-SQLAlchemy #Combines Flask and SQLAlchemy well
#Essence,: Each time the database is operated, a session connection will be automatically created, and it will be automatically closed when finished.
Blinker # signal
Wtforms #FORM component
Components and versions used
pip3 freeze #Get all installed modules in the environment
pip3 freeze > a.txt
pip3 freeze > requirements.txt
#pip3 install pipreqs #Help you find all modules of the current program, and automatically generate the requirements.txt file and write the content
pipreqs ./ #root directory
In the future, someone will give you a program to inform you of the components that need to be installed in a folder: requirements.txt
Enter the program directory:
pip install -r requirements.txt # will install all the designed components
structure:
app
static
templates
views
__init__.py
models.py