peewee爬坑

ashe 發(fā)布于2019-06-26 17:50 / 3113人閱讀

摘要：代碼示例用戶基本信息用戶名在視圖函數(shù)更新數(shù)據(jù)更新只有調(diào)用字段的值才會(huì)在改變項(xiàng)目使用的，使用了語法數(shù)據(jù)庫遷移管理，文檔，文檔

peewee update_time字段爬坑

SQLalchemy中BaseModel定義:

# -*- coding:utf-8 -*-
from datetime import datetime
from sqlalchemy import Column, DateTime
class BaseModel(object):
    """模型基類，為每個(gè)模型補(bǔ)充創(chuàng)建時(shí)間與更新時(shí)間"""

    create_time = Column(DateTime, default=datetime.now)  # 記錄的創(chuàng)建時(shí)間
    update_time = Column(DateTime, default=datetime.now, onupdate=datetime.now)  # 記錄的更新時(shí)間

peewee中的BaseModel定義:

# -*- coding: utf-8 -*-
from datetime import datetime
from peewee import Model, CharField
import peewee_async  # peewee_async異步操作MySQL
from configs import config

# 數(shù)據(jù)庫連接池
db = peewee_async.PooledMySQLDatabase(
    config.get("mysql_db"), host=config.get("mysql_host"), port=config.get("mysql_port"),
    user=config.get("user"), password=config.get("pwd"),
    min_connections=10,
    max_connections=50

)


class BaseModel(Model):
    """模型基類，為每個(gè)模型補(bǔ)充創(chuàng)建時(shí)間與更新時(shí)間"""
    create_time = DateTimeField(default=datetime.now, verbose_name="創(chuàng)建時(shí)間")  # 記錄的創(chuàng)建時(shí)間
    update_time = DateTimeField(default=datetime.now, verbose_name="更新時(shí)間")  # 記錄的更新時(shí)間

    def save(self, *args, **kwargs):
        """覆寫save方法, update_time字段自動(dòng)更新, 實(shí)例對(duì)象需要在update成功之后調(diào)用save()"""
        if self._get_pk_value() is None:
            # this is a create operation, set the date_created field
            self.create_time = datetime.now().strftime(
                "%Y-%m-%d %H:%M:%S")
        self.update_time = datetime.now().strftime(
            "%Y-%m-%d %H:%M:%S")
        return super(BaseModel, self).save(*args, **kwargs)

很明顯sqlalchemy定義的update_time字段的onupdate=datetime.now會(huì)在模型類的實(shí)例對(duì)象更新的時(shí)候自動(dòng)更新該字段的值；而peewee的update_time字段并沒有onupdate這個(gè)選項(xiàng)，從而無法實(shí)現(xiàn)自動(dòng)的更新時(shí)間，故而在BaseModel中覆寫了save方法，其他模型類繼承BaseModel，那么子類的實(shí)例對(duì)象在update成功之后調(diào)用對(duì)象的save方法可以達(dá)到更新update_time字段值的目的。
代碼示例：

class User(BaseModel):
    """用戶"""

    # 1 基本信息
    user_name= CharField(max_length=16, unique=True, null=False, verbose_name="用戶名")
    
    class Meta:
        database = db
        db_table = "user"

在視圖函數(shù)更新數(shù)據(jù):

# 更新
try:
    async with db.atomic_async():
        user.user_name= new_user_name
        await self.application.manager.update(user, only=["user_name"])
except Exception as err:
    self.application.logger.error(err)
    db.rollback()
else:
    # update_time
    user.save()  # 只有調(diào)用save() update_time字段的值才會(huì)在MySQL改變

NOTE：項(xiàng)目使用的tornado5.1，使用了async+await語法；數(shù)據(jù)庫遷移管理peewee-migrate，peewee文檔：http://docs.peewee-orm.com/en...， peewee-async文檔：https://peewee-async.readthed...