redis nodej redis nodejs promise

从异步，用延时来处理，改成同步获取数据
获取数据主要分2步:
1.从redis集合中获取数组；
2.遍历数组，抓取其中字符串，解析，拼接成需要的数据，返回给前端

原代码,用sleep方法，避免异步数据处理带来的提前返回数据的问题;

• (缺点:时间比较久，逻辑中是有问题的)

// 获取线路上公交的位置信息
app.post("/bus/getLineBusPos",async (req,res)=>{
    const { lineCode } = req.body;
    if(!lineCode){
        res.send({ret: 101, msg: '缺少线路参数'})
        return;
    }

    let data = await getredisdata(lineCode);
    await sleep(888); // 休眠 2 秒
    res.send({ret: 0, msg: '获取成功',data})
    return;
})

function sleep(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}


const getredisdata = async(lineCode) => {
     let shangxing = [],
         xiaxing = [];
     redisclient.smembers('xzspj_line_' + lineCode, (err, bus_arr) => {
         console.log('-------all,sets,bus_arr----------');
         console.log(bus_arr); // 输出集合中的所有元素
         bus_arr.forEach((item) => {
             //console.log(item)
             redisclient.get('xzspj_bus_' + item, function(err, res){
                 let businfo = JSON.parse(res);
                 console.log("get bus callback:" , businfo)
                 if(businfo){
                     //从主站开往副站为下行，从副站开往主站为上行
                     if(businfo.status == 0 || businfo.status == 4){
                         console.log('--shangxing');
                         shangxing.push(businfo)
                     }

                     if(businfo.status == 2 || businfo.status == 3){
                         xiaxing.push(businfo)
                     }
                 }
             });
         })
     });

     let data = {};
     data.shangxing = shangxing;
     data.xiaxing = xiaxing;
     return data;
}

优化后的代码

• 封装2个new Promise返回的方法
• for(const i of arr) 循环中才可以用 await,类似:forEach,each,map循环中不好放await

// 获取集合内容
function getSetContents(setName) {
    return new Promise((resolve, reject) => {
        // 以同步方式获取集合内容
        redisclient.smembers(setName, (err, members) => {
            if (err) {
                reject(err);
            } else {
                resolve(members);
            }
        });
    });
}

// 获取字符串内容
function getStrContents(strName) {
    return new Promise((resolve, reject) => {
        // 以同步方式获取集合内容
        redisclient.get(strName, (err, res) => {
            if (err) {
                reject(err);
            } else {
                resolve(res);
            }
        });
    });
}


const getredisdata = async(lineCode) => {
    let shangxing = [],
        xiaxing = [];

    try {
        const members = await getSetContents('xzspj_line_' + lineCode);
        console.log('members',members);
        for(const item of members){
            try {
                let res = await getStrContents('xzspj_bus_' + item);
                let businfo = JSON.parse(res);
                console.log("get bus callback:" , businfo)
                if(businfo){
                    //从主站开往副站为下行，从副站开往主站为上行
                    if(businfo.status == 0 || businfo.status == 4){
                        //console.log('--shangxing');
                        shangxing.push(businfo)
                    }
    
                    if(businfo.status == 2 || businfo.status == 3){
                        xiaxing.push(businfo)
                    }
                }
            } catch(err){
                console.log('err2-->',err);
            }
        }

        let data = {};
        data.shangxing = shangxing;
        data.xiaxing = xiaxing;
        return data;
    } catch(err){
        console.log('err1---->',err);
    } finally{

    }
    return;
} 


// 获取线路上公交的位置信息
app.post("/bus/getLineBusPos",async (req,res)=>{
    const { lineCode } = req.body;
    if(!lineCode){
        res.send({ret: 101, msg: '缺少线路参数'})
        return;
    }

    let data = await getredisdata(lineCode);
    //await sleep(888); // 休眠 2 秒----不用了
    res.send({ret: 0, msg: '获取成功',data})
    return;
})

相信坚持的力量，日复一日的习惯.