node.js 数组 Json

Question

有一个 JSON 数组。解码此 JSON 数据后，我想再次将其保存为 JSON 并发送数据。但我不知道如何正确发送数据。请使用 for 并承诺找到答案。

var AES256cryto = function (KeyValue) {
    return new Promise(function (resolve, reject) {
        var encrypt = ((val) => {
            let cipher = crypto.createCipheriv('aes-256-cbc', ENC_KEY, IV);
            let encrypted = cipher.update(val, 'utf8', 'base64');
            encrypted += cipher.final('base64');

            return encrypted;
        });

        //if (err) return reject(err);
        resolve(encrypt(KeyValue));
    });
}

var AES256decrypt = function (KeyValue) {
    return new Promise(function (resolve, reject) {
        var decrypt = ((encrypted) => {
            let decipher = crypto.createDecipheriv('aes-256-cbc', ENC_KEY, IV);
            let decrypted = decipher.update(encrypted, 'base64', 'utf8');

            return (decrypted + decipher.final('utf8'));
        });

        resolve(decrypt(KeyValue));
    });
}

　

if (rows) {
        var userinfoArray = new Array();

        for (var i = 0; i < rows.rows.length; i++) {
            Promise.all([AES256decrypt(rows.rows[i].admin), AES256decrypt(rows.rows[i].email), AES256decrypt(rows.rows[i].name)])
                .then(([adminDecrypt, emailDecrypt, nameDecrypt]) => {
                    var userinfo = new Object();

                    userinfo.admin = adminDecrypt;
                    userinfo.email = emailDecrypt;
                    userinfo.name = nameDecrypt;

                    userinfoArray.push(userinfo);
                }).catch(callback);


        }

    socket.emit('UserDataOK', userinfoArray);
    }

Answer 1

你在这个sn-p中的问题

var userinfoArray = new Array();

for (var i = 0; i < rows.rows.length; i++) {
    Promise.all([AES256decrypt(rows.rows[i].admin), AES256decrypt(rows.rows[i].email), AES256decrypt(rows.rows[i].name)])
        .then(([adminDecrypt, emailDecrypt, nameDecrypt]) => {
            var userinfo = new Object();

            userinfo.admin = adminDecrypt;
            userinfo.email = emailDecrypt;
            userinfo.name = nameDecrypt;

            userinfoArray.push(userinfo);
        }).catch(callback);


}

socket.emit('UserDataOK', userinfoArray);

是这样的说法

socket.emit('UserDataOK', userinfoArray);

由于这里是异步处理的，所以不保证在数组用所有for循环数据初始化后执行。

您可以将这一行移到最后一个承诺，向您的数组添加一个元素，如下所示：

var userinfoArray = new Array();
let expected_array_length = rows.rows.length;

for (var i = 0; i < rows.rows.length; i++) {
    Promise.all([AES256decrypt(rows.rows[i].admin), AES256decrypt(rows.rows[i].email), AES256decrypt(rows.rows[i].name)])
        .then(([adminDecrypt, emailDecrypt, nameDecrypt]) => {
            var userinfo = new Object();

            userinfo.admin = adminDecrypt;
            userinfo.email = emailDecrypt;
            userinfo.name = nameDecrypt;

            userinfoArray.push(userinfo);
            if(userinfoArray.length == expected_array_length) {
                socket.emit('UserDataOK', userinfoArray);
            }
        }).catch(function(err){expected_array_length -= 1; callback(err)}); // decrease rows.rows.length on your callback for each failing insert
}

这样，您将保证在发送消息时最后一个承诺已解决。

另一种方法是定义一个表示填充数组完成的承诺，以便您可以在此承诺解决时继续运行代码，然后立即发送消息。通过定义

const fillData = function(){
    var userinfoArray = new Array();
    return new Promise(async function (resolve, reject) {
        for (var i = 0; i < rows.rows.length; i++) {
            try{
            [adminDecrypt, emailDecrypt, nameDecrypt] = await Promise.all([AES256decrypt(rows.rows[i].admin), AES256decrypt(rows.rows[i].email), AES256decrypt(rows.rows[i].name)])
            var userinfo = new Object();

            userinfo.admin = adminDecrypt;
            userinfo.email = emailDecrypt;
            userinfo.name = nameDecrypt;

            userinfoArray.push(userinfo);
            } catch(err){
                callback(err)
            }
        }
        resolve(userinfoArray)
    })
}

你可以这样调用它来发送关于承诺解决的消息

fillData(rows)
.then(function(userinfoArray){
    socket.emit('UserDataOK', userinfoArray);
}, function(err){})