flask database connection pool DBUtils

Database connection pool

Why would you use the database connection pool

• Frequent connection and disconnection database, consumption, low efficiency
• DBUtils can create multiple threads connect to the database, and always connected, not disconnected
• When performing database operations, the data pool allocating threads, when the data pool empty, waiting for selectively polishing or wrong

installation

pip3 install DBUtils

Basic usage

• Create a data pool
  `` `Python
  Import Time
  Import Threading

  import pymysql
  from DBUtils.PooledDB import PooledDB

  # Create a database connection pool
  the POOL = PooledDB (
  Creator = pymysql,
  MaxConnections = 20 is, # define the maximum number of connections
  mincached 2, # define the starting number of connections =
  Host '127.0.0.1', =
  blocking = True, used up connection pool # , True is waiting, False when throwing error
  Port = 3306,
  User = 'the root',
  password = '123',
  Database = 'poolDB',
  charset = 'UTF8'
  )

  # Database connection pool to obtain a connection
  conn = POOL.connection ()

  cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
  cursor.execute('select * from tb1')
  result = cursor.fetchall()

  # Put this connection back to the connection pool
  conn.Close ()
  `` `

Application in the flask

• The definition of
  `` `
  Import pymysql

  from DBUtils.PooledDB import PooledDB

  SQLHelper class (Object):
  DEF the init (Self):
  # Create a database connection pool
  self.pool = PooledDB (
  Creator = pymysql,
  MaxConnections =. 5,
  mincached = 2,
  blocking = True,
  Host = '127.0.0.1',
  Port = 3306 ,
  User = 'the root',
  password = '123',
  Database = 's23day02',
  charset = 'UTF8'
  )

    def connect(self):
        conn = self.pool.connection()
        cursor = conn.cursor()
        return conn,cursor
  
  
    def disconnect(self,conn,cursor):
        cursor.close()
        conn.close()
  
  
    def fetchone(self,sql,params=None):
        """
        获取单条
        :param sql:
        :param params:
        :return:
        """
        if not params:
            params = []
        conn,cursor = self.connect()
        cursor.execute(sql, params)
        result = cursor.fetchone()
        self.disconnect(conn,cursor)
        return result
  
  
    def fetchall(self,sql,params=None):
        """
        获取所有
        :param sql:
        :param params:
        :return:
        """
        import pymysql
        if not params:
            params = []
        conn, cursor = self.connect()
        cursor.execute(sql,params)
        result = cursor.fetchall()
        self.disconnect(conn, cursor)
        return result
  
  
    def commit(self,sql,params):
        """
        增删改
        :param sql:
        :param params:
        :return:
        """
        import pymysql
        if not params:
            params = []
  
        conn, cursor = self.connect()
        cursor.execute(sql, params)
        conn.commit()
        self.disconnect(conn, cursor)

  db = SQLHelper()
  ```

• Example single mode

  from flask import Blueprint,url_for,request,render_template,session,redirect
  from ..utils.sqlhelper import db
  
  # 创建了一个蓝图对象
  account = Blueprint('account',__name__)
  
  
  
  @account.route('/login',methods=['GET','POST'])
  def login():
  
      if request.method == 'GET':
          return render_template('login.html')
      user = request.form.get('user')
      pwd = request.form.get('pwd')
  
      # 根据用户名和密码去数据库进行校验
      # 连接/SQL语句/关闭
      result = db.fetchone('select * from user where username=%s and password=%s',[user,pwd])
      if result:
          # 在session中存储一个值
          session['user_info'] = user
          return redirect(url_for('user.user_list'))
      return render_template('login.html',error="用户名或密码错误")

[Description] SQLhelper class

• Related methods package database operations, so that after the transfer of business functions, reducing code when a certain degree of repetition
• With DBUtils, greatly improving the operating efficiency of the database