node.js - MongoDB 字段返回一个数字，但使 javascript 变量未定义

Question

这个问题已经有答案了:

Why is my variable unaltered after I modify it inside of a function? - Asynchronous code reference (7 个回答)

已关闭 4 年前。

值(value)

found.totalfunds = 99

但是当我将它分配给变量时

funds

它在 console.log(funds) 上返回未定义

 router.get("/:id/managefunds/",middleware.isLoggedIn,function(req,res){

    console.log("Manage Funds");
     var societyId = req.params.id;
     // res.send(societyId);
     var funds ;
     Society.findById({_id:societyId},function(err,found){
        console.log("fromMongo"+found.totalFunds);
        funds = found.TotalFunds;
     });
     console.log("FUNDSSSS: "  + funds);

     res.render("campgrounds/managefunds",{parm:societyId,funds});

});

console.log("fromMongo"+found.totalFunds);这将返回我默认设置的数字。

Answer 1

Society.findById 有一个回调，因为它是异步。

您必须修改代码才能仅在执行回调时继续:

router.get("/:id/managefunds/",middleware.isLoggedIn,function(req,res){

    console.log("Manage Funds");
     var societyId = req.params.id;
     // res.send(societyId);
     var funds ;
     Society.findById({_id:societyId},function(err,found){
        console.log("fromMongo"+found.totalFunds);

        funds = found.TotalFunds;     console.log("FUNDSSSS: "  + funds);

        res.render("campgrounds/managefunds",{parm:societyId,funds});
     });
});