使用Mongoose和Node.js将数据保存到集合中时出错

Question

使用Node.js和Mangoose将记录插入集合时，出现以下错误。

错误：

OverwriteModelError: Cannot overwrite `alloca_temp` model once compiled.
   at new OverwriteModelError (/home/subrajyoti/Desktop/landing/node_modules/mongoose/lib/error/overwriteModel.js:20:11)
   at NativeConnection.Connection.model (/home/subrajyoti/Desktop/landing/node_modules/mongoose/lib/connection.js:776:13)
   at exports.createCollections (/home/subrajyoti/Desktop/landing/controller/controller.js:162:19)
   at Layer.handle [as handle_request] (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/layer.js:95:5)
   at next (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/route.js:131:13)
   at Route.dispatch (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/route.js:112:3)
   at Layer.handle [as handle_request] (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/layer.js:95:5)
   at /home/subrajyoti/Desktop/landing/node_modules/express/lib/router/index.js:277:22
   at Function.process_params (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/index.js:330:12)
   at next (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/index.js:271:10)
   at methodOverride (/home/subrajyoti/Desktop/landing/node_modules/method-override/index.js:65:14)
   at Layer.handle [as handle_request] (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/layer.js:95:5)
   at trim_prefix (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/index.js:312:13)
   at /home/subrajyoti/Desktop/landing/node_modules/express/lib/router/index.js:280:7
   at Function.process_params (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/index.js:330:12)
   at next (/home/subrajyoti/Desktop/landing/node_modules/express/lib/router/index.js:271:10)

我在下面提供我的代码。

mongoose.connect(url+"/"+database,{ useNewUrlParser: true });
var db = mongoose.connection;
db.on("error", console.error.bind(console, "connection error"));
db.once("open", function(callback) {
     console.log("Connection succeeded.");
});
//console.log('db1',db);
var Schema = mongoose.Schema;
exports.createCollections=function(req,res){
   var userSchema=new Schema({
        login_id: String,
        password: String,
        full_name: String,
        user_type: Number,
        role_type: String,
        allocated_to: Number,
        zone: Number,
        state: Number,
        location: Number,
        is_active: Number,
        added_on: Date,
        device_id: { type: String, default:"" },
        access_key: String 
    })
    var tempmodel=db.model('alloca_temp', tempSchema);
    tempmodel.find({},function(err,docs){
        //console.log('docs',docs);
        //res.send(docs);
        tempArr=docs;
        //res.send(tempArr);
        var user = db.model("User", userSchema);
        var password='123456';
        for(var i=0;i<tempArr.length;i++){
            var haspass='';
            bcrypt.genSalt(10, function(err, salt) {
                bcrypt.hash(password, salt, function(err, hash) {
                   haspass=hash;
                });
            });
            var data='';
            data={
                login_id:tempArr[i]['login_mobile_no'],
                password:haspass,
                full_name: tempArr[i]['customer_name'],
                user_type: 4,
                role_type: 'AGENCY FOS',
                allocated_to: tempArr[i]['allocated_to'],
                zone: tempArr[i]['zone'],
                state: tempArr[i]['state'],
                location: tempArr[i]['location'],
                is_active: 1,
                added_on: todaydate(),
                device_id: "",
                access_key: ""
            }
            var use=new user(data);
            use.save(function(err,user){
                if (!err) {
                    console.log('id',user._id);
                }
            })
        }
    })
})

在这里，我从一个集合中获取值，需要插入另一个集合中，但出现此错误。