PostgreSQL Node.js实现函数计算方法示例

const { Pool } = require('pg');const config = require('../config/default.js');const { database: { HOST, PORT, DATABASE, USERNAME, PASSWORD, },} = config;const pool = new Pool({ port: PORT, host: HOST, user: USERNAME, password: PASSWORD, database: DATABASE,});/** *  * @param sql 接收的sql语句 * @param {Array} values sql语句参数 * @return { Object } { success: boolean, err || data } */const query = async function( sql = 'select NOW()', values = []) { return new Promise(resolve => { pool.connect((err, client, release) => { if (err) { return console.error('Error acquiring client', err.stack) } const params = Array.isArray(values) ? [...values] : [values]; client.query(sql, params, (error, result) => { release(); if (error) {  console.error('Error executing query', error.stack);  resolve({  success: false,  error,  }); } resolve({  success: true,  data: result.rows, }); }); }); });}module.exports = { query,}

const config = { // 数据库配置 database: { DATABASE: 'databasename', USERNAME: 'root', PASSWORD: '123456', PORT: '3433', HOST: 'localhost', },};module.exports = config;

const pool = require('../lib/postgre'); // 导入封装好的mysql库const { query } = pool; // 导入query方法class BaseController { constructor() { } // 查询表内所有数据（非删除） async list() { const sql = `select * from ${this.table}`; return await query(sql); } async excute(sql, vals = []) { // 执行方法 return await query(sql, vals); } // log 方法 log({func, err}) { console.log(`excute function[${func}] occured error : ${err.message || err}`); }}module.exports = BaseController;

const BaseController = require('./BaseController'); // 获得基类// 继承基类class InqueryController extends BaseController { constructor() { super(); this.table = 'data_table'; // 赋值table } // 可以重写基类的方法，如果有业务需要 async list() { const sql = `select * from ${this.table} ORDER BY created_at DESC `; return await this.excute(sql); } async getUnsendCustomer(vals) { const sql = `select * from ${this.table} where created_at > $1 ORDER BY created_at DESC`; // 统一在基类调用sql参数 return await this.excute(sql, vals); } }module.exports = InqueryController;

// 需要绑定this的方法const funcs = [ 'list',]class BaseService { constructor() { this.controller = null; // 循环遍历绑定this, 在koa绑定route的时可用到 funcs.forEach(item => {  this[item] = this[item].bind(this) }); } // 查询方法 async list(ctx) { if (!ctx) {  return await this.controller.list(); } // controller返回的是一个对象，success(成功为true， 失败为false), data(成功则有此数据), err(失败则有此对象) const { success: flag, data, error } = await this.controller.list(); if (flag) {  // success  ctx.body = {  data,  code: 200,  } } else {  // failed  ctx.body = {  code: 500,  error,  }; } }}module.exports = BaseService

// 导入基类const BaseService = require('./BaseService');// 导入对应的controllerconst Controller = require('../controller/InqueryController');// 获取MailSender Serviceconst MailService = require('./MailSender');const Helper = require('../util/Helper');const funcs = [ 'unsendUser',];// 生成一次controllerconst controller = new Controller();class InqueryService extends BaseService { constructor() { super() // 绑定对应的controller this.controller = controller; funcs.forEach(item => {  this[item] = this[item].bind(this); }); } getMailOpts(i) { // you can use the data from database to combine the message const message = 'Hello world!'; return return {  message,  // 可以从配置文件读取或者oss  to: 'xxxx@gmail.com',  subject: 'Hello World', }; }  async unsendUser() { const list = await this.controller.list(); if (list.length > 0) {  const mailer = new MailService();  const errorList = [];  iterateList.forEach(async i => {  const mailerOption = this.getMailOpts(i);  const { success, ...rest } = await mailer.sendToAuitAdmin(mailerOption);  if (!success) {   errorList.push(rest);  }  });  const lastestTime = iterateList[0].created_at;  if (errorList.length === 0) {  return {   code: 200,   message: 'Success',  };  } } else {  return {  code: 204,  message: 'No user found',  }; } }}module.exports = new InqueryService();

const inqueryService = require('./services/InqueryService'); exports.handler = async function(event, context, callback) { const result = await inqueryService.unsendUser(); callback(null, result);};