PostgreSQL Node.js實(shí)現(xiàn)函數(shù)計(jì)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語(yǔ)句
 * @param {Array} values sql語(yǔ)句參數(shù)
 * @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 = {
 // 數(shù)據(jù)庫(kù)配置
 database: {
 DATABASE: 'databasename',
 USERNAME: 'root',
 PASSWORD: '123456',
 PORT: '3433',
 HOST: 'localhost',
 },
};

module.exports = config;

const pool = require('../lib/postgre'); // 導(dǎo)入封裝好的mysql庫(kù)
const { query } = pool; // 導(dǎo)入query方法
class BaseController {
 constructor() {
 }
 // 查詢表內(nèi)所有數(shù)據(jù)（非刪除）
 async list() {
 const sql = `select * from ${this.table}`;
 return await query(sql);
 }
 async excute(sql, vals = []) {
 // 執(zhí)行方法
 return await query(sql, vals);
 }
 // log 方法
 log({func, err}) {
 console.log(`excute function[${func}] occured error : ${err.message || err}`);
 }
}

module.exports = BaseController;

const BaseController = require('./BaseController'); // 獲得基類
// 繼承基類
class InqueryController extends BaseController {
 constructor() {
 super();
 this.table = 'data_table'; // 賦值table
 }
 // 可以重寫基類的方法，如果有業(yè)務(wù)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`;
 // 統(tǒng)一在基類調(diào)用sql參數(shù)
 return await this.excute(sql, vals);
 }
 
}
module.exports = InqueryController;

// 需要綁定this的方法
const funcs = [
 'list',
]
class BaseService {
 constructor() {
 this.controller = null;
 // 循環(huán)遍歷綁定this, 在koa綁定route的時(shí)可用到
 funcs.forEach(item => {
 this[item] = this[item].bind(this)
 });
 }

 // 查詢方法
 async list(ctx) {
 if (!ctx) {
 return await this.controller.list();
 }
 // controller返回的是一個(gè)對(duì)象，success(成功為true， 失敗為false), data(成功則有此數(shù)據(jù)), err(失敗則有此對(duì)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

// 導(dǎo)入基類
const BaseService = require('./BaseService');
// 導(dǎo)入對(duì)應(yīng)的controller
const Controller = require('../controller/InqueryController');
// 獲取MailSender Service
const MailService = require('./MailSender');
const Helper = require('../util/Helper');

const funcs = [
 'unsendUser',
];
// 生成一次controller
const controller = new Controller();
class InqueryService extends BaseService {
 constructor() {
 super()
 // 綁定對(duì)應(yīng)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,
 // 可以從配置文件讀取或者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);
};