Question

我正在尝试从sql server数据库中获取数据（我正在使用mssql模块执行此操作：https://www.npmjs.com/package/mssql）并将其发送到Redis。所以我创建了三个文件：

sql_server.js 包含与sql_server相关的所有功能（如与数据库和查询的连接）
redis.js 具有连接和set key / value等函数到redis数据库（键是一个ID，值是sql_server查询的结果）
server.js 是调用sql_server和redis文件的函数并充当控制器的主文件

我想流式传输sql_server数据库，并将结果发送给server.js，以便返回每一行。然后server.js文件将结果传递给redis函数，该函数将创建一对键/值。

但我对node.js不太熟悉，我不知道如何将查询结果返回给每一行的server.js：

这是 sql_server.js 函数来流式传输数据库

      execRequests: function(requestEntry, flux){
    try{            
        const request = new sql.Request(pool)
        request.stream = true // You can set streaming differently for each request 
        request.query(requestEntry)// or request.execute(procedure) 

        request.on('recordset', columns => {
            //console.log(columns); 
        })

        request.on('row', row => {
            // THAT I AM DOING FOR NOW
            //redisMethods.setValue(JSON.stringify(row), flux);
            // THAT I WOULD LIKE TO TO
            //return row;
        })

        request.on('error', err => {
            // May be emitted multiple times 
        })

        request.on('done', result => {
            console.log("done for flux :" + flux);
        })



    } catch (err){
        console.log(err);
    }
}

这是 server.js

    sqlMethods.connection().then(function(pool){
    try{
        if(pool._connected){
            console.log("Connected to SQL Server database : " + pool.config.database);
            // connection to redis database
            redisMethods.connection();
            // get the requests to execute
            sqlMethods.getRequests().then(function(requestArray){
                // loop over the array containing requests
                for (var i in requestArray){
                    let request = requestArray[i].requete; //extract the request
                    let flux = requestArray[i].flux; //extract the flux name
                    sqlMethods.execRequests(request, flux).then(function(result){
                       // redisMethods.setValue(JSON.stringify(result), flux);
                    });
                }
            });
        }
    } catch (err){
        console.log(err);
    }

希望我的解释是可以理解的，我需要你的帮助才能找到一种方法将行从sql_server.js返回到server.js。谢谢！

Answer 1

我可以建议您使用回调函数来传递错误或数据。

   execRequests: function(requestEntry, flux, callback){
    const request = new sql.Request(pool);
    request.stream = true; // You can set streaming differently for each request 
    request.query(requestEntry); // or request.execute(procedure) 

    var errors = [];
    var rows = [];

    request.on('recordset', columns => {
        //console.log(columns); 
    });

    request.on('row', row => {
        // THAT I AM DOING FOR NOW
        //redisMethods.setValue(JSON.stringify(row), flux);
        // THAT I WOULD LIKE TO TO
        //return row;
        rows.push(row);
    });

    request.on('error', err => {
        // May be emitted multiple times 
        errors.push(err);
    });

    request.on('done', result => {
        console.log("done for flux :" + flux);
        callback(errors, rows);
    });
}

然后在你的server.js

sqlMethods.connection().then(function(pool) {
    try {
        if (pool._connected) {
            console.log("Connected to SQL Server database : " + pool.config.database);
            // connection to redis database
            redisMethods.connection();
            // get the requests to execute
            sqlMethods.getRequests().then(function (requestArray) {
                // loop over the array containing requests
                for (var i in requestArray) {
                    let request = requestArray[i].requete; //extract the request
                    let flux = requestArray[i].flux; //extract the flux name
                    sqlMethods.execRequests(request, flux, function (errors, rows) {
                        if (errors && errors.length) {
                            // There is errors
                        }
                        else if (rows && rows.length) {
                            // There is no errors but rows
                        }
                    });
                }
            });
        }
    } catch (err) {
        console.log(err);
    }
});

希望它有所帮助。

从mssql模块中的异步函数返回数据

1 个答案: