Question

我有一组api，我将数据发布到数据库，作为响应，我从数据库中以json形式获取所需的响应。我面临的问题是，当我第一次发布数据时，它会被发布，第二次我的服务器将崩溃并提供错误：发送后无法设置标头。我不知道为什么我会收到此错误。请让我知道我哪里出错了

router.post('/addcustomerskills', function(req,res) {
    var skill = req.body.skill;
    var skill_id = req.body.skill_id;
    var skill_name = req.body.skill_name;
    var rating = req.body.rating;
    var response = {};

    if (typeof skill ==='undefined') {
        response.token = '2ewerr4';
        response.success = false,
        response.skill = null;
        response.mssg = 'fields cannot be empty';
        res.json(response);
    } else {
        var j =1;
        for (i in skill) {
            var skillObj=skill[i];  
            db.query('INSERT into skill(skill_id,skill_name,rating) values(?,?,?)', [skillObj.skill_id, skillObj.skill_name, skillObj.rating], function(error, rows) {
                if (error) {
                    res.json(error);
                } else {        
                    db.query('select id,skill_id,skill_name,rating FROM skills WHERE skill_id = ?', [skillObj.skill_id], function(error, rows) {
                        response.success = true,
                        //response.skills = rows;
                        response.skills = skill;
                        response.mssg = 'Successfully Updated';
                        if(j === 1) {
                            j = 0;
                            res.json(response);
                        }           
                    })
                }
            });
        }
    }
});

Answer 1

因为db.query()以异步方式工作，您遇到了这个问题。

所以，试试这个

router.post('/addcustomerskills', function(req,res) {
    var skill = req.body.skill;
    var skill_id = req.body.skill_id;
    var skill_name = req.body.skill_name;
    var rating = req.body.rating;
    var response = {};

    if (typeof skill ==='undefined') {
        response.token = '2ewerr4';
        response.success = false,
        response.skill = null;
        response.mssg = 'fields cannot be empty';
        res.json(response);
    } else {
        var i, count = 0;
        // var j = 1;
        var result = [];
        for (i in skill) {
            count++;
            var skillObj=skill[i];  
            db.query('INSERT into skill(skill_id,skill_name,rating) values(?,?,?)', [skillObj.skill_id, skillObj.skill_name, skillObj.rating], function(error, rows) {
                if (error) {
                    result.push(response);
                    response = {};
                    if(count == skill.length){
                        res.json(result);
                    }
                } else {        
                    db.query('select id,skill_id,skill_name,rating FROM skills WHERE skill_id = ?', [skillObj.skill_id], function(innerError, innerRows) {
                        response.success = true,
                        //response.skills = innerRows;
                        response.skills = skill;
                        response.mssg = 'Successfully Updated';

                        // I don't understand why you have used the variable 'j', so I commented it
                        // if(j === 1) {
                        //     j = 0;
                        //     res.json(response);
                        // }           

                        result.push(response);
                        response = {};
                        if(count == skill.length){
                            res.json(result);
                        }
                    });
                }
            });
        }
    }
});

此外，当您嵌套db.query()

时，您应该使用单独的变量名称

Answer 2

错误：发送后无法设置标头。

具有简单的含义，即您多次发送res。

@SRK这里的错误就是这个

每次查询数据库时，您都会for loop发送res。

在for循环结束后发回响应。

router.post('/addcustomerskills', function(req,res) {
    var skill = req.body.skill;
    var skill_id = req.body.skill_id;
    var skill_name = req.body.skill_name;
    var rating = req.body.rating;
    var response = {};

    if (typeof skill ==='undefined') {
        response.token = '2ewerr4';
        response.success = false,
        response.skill = null;
        response.mssg = 'fields cannot be empty';
        res.json(response);
    } else {
        var j =1;
        for (i in skill) {
            var skillObj=skill[i];  
            db.query('INSERT into skill(skill_id,skill_name,rating) values(?,?,?)', [skillObj.skill_id, skillObj.skill_name, skillObj.rating], function(error, rows) {
                if (error) {

                } else {        
                    db.query('select id,skill_id,skill_name,rating FROM skills WHERE skill_id = ?', [skillObj.skill_id], function(error, rows) {
                        response.success = true,
                        //response.skills = rows;
                        response.skills = skill;
                        response.mssg = 'Successfully Updated';
                        if(j === 1) {
                            j = 0;

                        }           
                    })
                }
            });
        }
    res.json({"message":"what you want to send"});
    }
});

如果你想处理crush，请在你的主node.js文件中添加它

process.on('uncaughtException', (err) => {
  console.log("error",error);
});

nodejs中的服务器崩溃问题

2 个答案: