Javascript TypeError:无法读取属性'；标题'；未定义Nodejs Mysql查询结果的类型

这个错误并不总是发生，但它经常发生，我找不到任何解决方案。任何帮助都将不胜感激

PS：数据库中的表有“title”列，其中包含数据

代码：

 async function selectNotificationData(control_message_id){
const sql = await new Promise((res,rej)=>{
    let query = "SELECT title, body ,url_push, img_push, url_type, status,silent,channel FROM control_message WHERE id_control_message =?";
    con.query(query, [control_message_id],(err,row)=>{
        if(err) throw err;
        let n =row[0];
        let pf=null;
        try{
            pf =  setPerFlagOptmized(n.title,n.body);
            res({not_data:n,pf})
        }
        catch (err) {

            console.log("[Row : "+row[0]+"]");
            console.log("[n : "+n+"]");
            console.log("ERROR IN SELECTING NOT DATA OR SETTING THE FLAG : "+err);
        }


    })
}).catch((error)=>{
    console.log("ERROR IN SELECTING Notification DATA : "+error);
});

app_1    | /usr/src/app/node_modules/mysql/lib/protocol/Parser.js:437
app_1    |       throw err; // Rethrow non-MySQL errors
app_1    |       ^
app_1    |
app_1    | TypeError: Cannot read property 'title' of undefined
app_1    |     at Query.con.query (/usr/src/app/v4/message/controllers/expandWorker.js:669:57)
app_1    |     at Query.<anonymous> (/usr/src/app/node_modules/mysql/lib/Connection.js:526:10)
app_1    |     at Query._callback (/usr/src/app/node_modules/mysql/lib/Connection.js:488:16)
app_1    |     at Query.Sequence.end 
(/usr/src/app/node_modules/mysql/lib/protocol/sequences/Sequence.js:83:24)
app_1    |     at Query._handleFinalResultPacket 
(/usr/src/app/node_modules/mysql/lib/protocol/sequences/Query.js:149:8)
app_1    |     at Query.EofPacket 
(/usr/src/app/node_modules/mysql/lib/protocol/sequences/Query.js:133:8)
app_1    |     at Protocol._parsePacket 
(/usr/src/app/node_modules/mysql/lib/protocol/Protocol.js:291:23)
app_1    |     at Parser._parsePacket 
(/usr/src/app/node_modules/mysql/lib/protocol/Parser.js:433:10)
app_1    |     at Parser.write (/usr/src/app/node_modules/mysql/lib/protocol/Parser.js:43:10)
app_1    |     at Protocol.write (/usr/src/app/node_modules/mysql/lib/protocol/Protocol.js:38:16)

错误：

 async function selectNotificationData(control_message_id){
const sql = await new Promise((res,rej)=>{
    let query = "SELECT title, body ,url_push, img_push, url_type, status,silent,channel FROM control_message WHERE id_control_message =?";
    con.query(query, [control_message_id],(err,row)=>{
        if(err) throw err;
        let n =row[0];
        let pf=null;
        try{
            pf =  setPerFlagOptmized(n.title,n.body);
            res({not_data:n,pf})
        }
        catch (err) {

            console.log("[Row : "+row[0]+"]");
            console.log("[n : "+n+"]");
            console.log("ERROR IN SELECTING NOT DATA OR SETTING THE FLAG : "+err);
        }


    })
}).catch((error)=>{
    console.log("ERROR IN SELECTING Notification DATA : "+error);
});

app_1    | /usr/src/app/node_modules/mysql/lib/protocol/Parser.js:437
app_1    |       throw err; // Rethrow non-MySQL errors
app_1    |       ^
app_1    |
app_1    | TypeError: Cannot read property 'title' of undefined
app_1    |     at Query.con.query (/usr/src/app/v4/message/controllers/expandWorker.js:669:57)
app_1    |     at Query.<anonymous> (/usr/src/app/node_modules/mysql/lib/Connection.js:526:10)
app_1    |     at Query._callback (/usr/src/app/node_modules/mysql/lib/Connection.js:488:16)
app_1    |     at Query.Sequence.end 
(/usr/src/app/node_modules/mysql/lib/protocol/sequences/Sequence.js:83:24)
app_1    |     at Query._handleFinalResultPacket 
(/usr/src/app/node_modules/mysql/lib/protocol/sequences/Query.js:149:8)
app_1    |     at Query.EofPacket 
(/usr/src/app/node_modules/mysql/lib/protocol/sequences/Query.js:133:8)
app_1    |     at Protocol._parsePacket 
(/usr/src/app/node_modules/mysql/lib/protocol/Protocol.js:291:23)
app_1    |     at Parser._parsePacket 
(/usr/src/app/node_modules/mysql/lib/protocol/Parser.js:433:10)
app_1    |     at Parser.write (/usr/src/app/node_modules/mysql/lib/protocol/Parser.js:43:10)
app_1    |     at Protocol.write (/usr/src/app/node_modules/mysql/lib/protocol/Protocol.js:38:16)

setPerFlagOptmized功能：

 function setPerFlagOptmized(title,body){
    var t = (title.includes("|*") || title.includes("*|") || title.includes("{{") || title.includes("}}"));
    var b = (body.includes("|*") || body.includes("*|") || body.includes("{{") || body.includes("}}"));
    return (t || b) ? 1:0;
}

---

当找不到给定查询的记录时，可能会发生这种情况。 在这种情况下，回调中的

err

将不会被定义，相反

row

只是一个空数组

由于您没有对此进行检查，并且直接访问

行[0]

，这将产生

未定义的
，因此会为
n.title
引发错误。因此，您应该添加以下检查：

if(err) throw err;

if (!row.length) {
   // handle error - throw or return here
}
// ..rest of the code

谢谢你的回答，我会试试看，是不是查询遇到了锁超时而什么也没有返回？好问题，但我认为回调中的错误会在这些情况下被定义。我想我需要检查数据库是否抛出了innodb锁信息，这会影响“innodb\u打印\u锁\u等待\u超时\u信息”？嗯，好的，老实说，我在这里不太确定。。也许其他人有主意。对不起：/没关系，伙计，非常感谢你的帮助