node.js - Node JS - 当我想显示来自 Mongoose 的列表时异步

Question

当我想在 ejs 中将 Mongoose (MongoDB) 的数据列表显示到我的前端时遇到问题

例如:

var User = require("./models/user");
var Houses = require("./models/house");

app.get("/", function(req, res){
    var list_houses = [];
    for(var i=0; i<req.user.city.length; i++)
    {
        Houses.find({'city': req.user.city[i]}, function(err, result){
            if(err)console.log(err);
            if(result){
                list_houses = list_houses.concat(result);//add array result to array list_prices
            }
        }); 
    }
    res.render("/prices_houses",{list_houses: list_houses});
});

我找到了“async”模块，但两者都不起作用，我的代码是:

var User = require("./models/user");
var Houses = require("./models/house");
var async = require('async');

app.get("/", function(req,res){
    var list_houses = [];
    async.waterfall([
        async.each(req.user.city, function(result, callback){
            Houses.find({'city': result}, function(err, result){
                if(err)console.log(err);
                if(result){
                    list_houses = list_houses.concat(result);
                }
            });
        });
    ], function(arg1, callback){
        res.render("/prices_houses", {list_houses: list_houses});
    });
});

当我想在ejs中显示'list_houses.length'时，它显示:0

<%=list_houses.length%>

我在 Mongoose 中的架构是:

var User = new mongoose.Schema({
    city : [String] 
    ...
});

var House = new mongoose.Schema({
    city: String
    price: Double
});

我知道问题出在异步，但我不知道如何解决。请帮我解决这个问题。

Answer 1

我认为你把事情搞得太复杂了。似乎您可以仅使用 $in 运算符来实现此目的。大致如下:

Houses.find({'city': {$in: req.user.city}}, function(err, results){
    if(err)console.log(err);
    console.log(results); // this should be an array of all houses in all cities that the user has in their city array
});