mysql - 我想从 nodejs 获得对 angular 6 的响应

Question

如果插入查询成功，我想发送响应消息，否则 nodejs 应该向 angular 6 发送不成功的消息并在浏览器上显示 //Node 文件

exports.create = (req, res) => {
    let uname = req.body.username;
    let mail = req.body.email;


    con.query('SELECT username FROM customers WHERE username = ?', uname,(err,result)=>{

        if(err) throw err;
        con.query('SELECT email FROM customers WHERE email = ?', mail,(err, results) => {
            if(err) throw err;
            if(result.length !=0 || results.length != 0){
                console.log('email and username already exists');
                res.send({msg:"already registered with the email and username"});
            }
            else{
                con.query('INSERT INTO customers SET ?', req.body, (err, results) => {
                    if(err) throw err;
                    res.status(200).json(results);
                });
            }
        });
    });
};
//service.ts file
addCustomer (customer: Customer): Observable<Customer> {

    return this.http.post<Customer>(this.customersUrl, customer, httpOptions);
}

//create component file
addCustomer() {
    this.submitted = true;
    this.save();
}
private save(): void {
    this.customerService.addCustomer(this.customer)
        .subscribe(result=>console.log('success'));
}

Answer 1

使用 then 链编写 api 函数。您可以在 catch 中获取错误。在成功函数和错误函数中返回你需要的任何东西。示例:

 getQueryResults()
       .then(processResultData)
       .then((result)=>{
         return result;
       })
       .catch((error)=>{
         return error;
       });