[英]Check if record exist before insert on Node JS database class
I made a class with a select, update and insert functions, but I would like to implement a check to see if the record exists before insert. 我用选择,更新和插入功能创建了一个类,但是我想实现一个检查,以检查插入之前记录是否存在。 I tried to create the logic above in the insert function, but I'm having some difficulty with the structure and syntax. 我试图在insert函数中创建上述逻辑,但是在结构和语法上遇到了一些困难。 Any suggestion? 有什么建议吗?
'use strict'; var User = require('../model/User.js'); exports.get_User_by_id = function(req, res) { User.getUserById(req.params.id, function(err, User) { if (err) res.send(err); res.json(User); }); }; exports.get_User_by_User_id = function(req, res) { var postedBody = [req.params.User_type, req.params.User_id]; User.getUserByIdUser(postedBody, function(err, User) { if (err) res.send(err); res.json(User); }); }; exports.add_User = function(req, res) { var new_User = new User(req.body); var postedBody = [new_User.User_type, new_User.User_id]; User.getUserByIdUser(postedBody, function(err, User) { if (err) { res.send(err); } else { if (User) { res.json(User); } else { // //handles null error if(!new_User.User_type || !new_User.User_id){ res.status(400).send({ error:true, message: 'Please provide type/id' }); } else{ User.insertUser(new_User, function(err, User) { if (err) res.send(err); res.json(User); }); } } } }); };
Edit 1: Following naga-elixir-jar examples, here is my full code: user.js (model) 编辑1:按照naga-elixir-jar示例,这是我的完整代码:user.js(模型)
var now = new Date(); function ISODateString(d) { function pad(n) {return n<10 ? '0'+n : n} return d.getUTCFullYear()+'-' + pad(d.getUTCMonth()+1)+'-' + pad(d.getUTCDate())+' ' + pad(d.getUTCHours())+':' + pad(d.getUTCMinutes())+':' + pad(d.getUTCSeconds())+'' } var User = function(User){ this.id = User.id; this.User_type = User.User_type; this.User_id = User.User_id; this.created_at = ISODateString(now); }; User.getUserByIdUser = function getUserByIdUser(body) { return new Promise((resolve, reject) => { sql.query("SELECT * FROM sb_Users WHERE User_type = ? AND User_id = ?", body, function (err, res) { if(err) { console.log("error: ", err); reject(err); } else{ resolve(res); } }); }) }; User.insertUser = function insertUser(newUser) { return new Promise((resolve, reject) => { sql.query("INSERT INTO sb_Users SET ?", newUser, function (err, res) { if(err) { console.log("error: ", err); reject(err); } else{ resolve(res); } }); }) };
User.js (Controller) User.js(控制器)
var User = require('../model/User.js'); exports.get_User_by_User_id = async function(req, res) { var postedBody = [req.params.User_type, req.params.User_id]; try { const User = User.getUserByIdUser(postedBody); if (User.length === 0) { res.json("not existent"); } else { res.json(User); } } catch(e) { console.error(e); res.json("oops! something is wrong"); } }; exports.add_User = async function(req, res) { var new_User = new User(req.body); var postedBody = [new_User.User_type, new_User.User_id]; try { const User = await User.getUserByIdUser(postedBody); // I think sql returns an array of object if found or empty array otherwise if so use if (user.length === 0) if (User) { res.json(User); } else { if(!new_User.User_type || !new_User.User_id){ res.status(400).send({ error:true, message: 'Please provide type/id' }); } else { const newUser = await User.insertUser(new_User); res.json(newUser); } } } catch(e) { // handle error console.error(e); res.json("oops! something is wrong"); } };
You could use Promise
to ease the complexity with callback. 您可以使用Promise
来减轻回调的复杂性。 Since mysql
does not provide Promise
support, you could promisify
your functions like: 由于mysql
不提供Promise
支持,因此您可以promisify
函数像下面这样:
// Some sample sql statement
User.getUserByIdUser = function getUserByIdUser(id) {
return new Promise((resolve, reject) => {
sql.query("Select * from users where id = ? ", id, function (err, res) {
if(err) {
console.log("error: ", err);
reject(err);
}
else{
resolve(res);
}
});
})
};
// same with User.insertUser
In you route: 在您的路线中:
exports.add_User = async function(req, res) {
var new_User = new User(req.body);
var postedBody = [new_User.User_type, new_User.User_id];
try {
const user = await User.getUserByIdUser(postedBody)
// I think sql returns an array of object if found or empty array otherwise if so use if (user.length === 0)
if (user) {
res.json(user);
} else {
if(!new_User.User_type || !new_User.User_id){
res.status(400).send({ error:true, message: 'Please provide type/id' });
} else {
const newUser = await User.insertUser(new_User)
res.json(newUser);
}
}
} catch(e) {
// handle error
console.error(e);
res.json("oops! something is wrong");
}
};
Note: mysql2
provides promise wrapper over mysql
so you could use that library instead of writing your own promise wrappers. 注意: mysql2
在mysql
之上提供了mysql2
包装器,因此您可以使用该库而不是编写自己的Promise包装器。
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