node.js - Node 中 Mongoose 模式引用的问题

Question

我对 Node、Mongoose 以及与后端相关的所有内容都很陌生。我最近遇到了一个问题。我无法弄清楚，因为开发类(class)练习文件中的相同代码似乎是相同的。然而问题仍然没有解决。我想要做的事情是，与教程一起编码，我想为 Mongo 数据库中我在页面上显示的每个露营地部分的注释定义一个 Mongoose 模型。我有一个 models 文件夹，我在其中定义露营地和评论的模型，还有一个 seeds.js 文件，我在其中动态地将数据添加到露营地(以便它立即与评论一起出现)，然后添加评论。这些文件的实际代码如下: app.js-->

var express = require("express");
var app = express();
var bodyParser = require("body-parser");
var mongoose = require('mongoose');
var Campground=require("./models/campground");
var seedDB = require("./seeds");
var PORT = process.env.IP || 3200;

seedDB();

mongoose.connect('mongodb://localhost/yelp_camp', { useNewUrlParser: true }, 
(err, res) => {
if (err) throw err;
console.log('Database online');
});
app.use(bodyParser.urlencoded({ extended: true }));
app.set("view engine", "ejs");

//schema

app.get("/", function (req, res) {
res.render("landing");

});

app.get("/campgrounds/tornike", function (req, res) {
//get all campgrounds
res.send(Campground.name);

});

app.get("/campgrounds", function (req, res) {
//get all campgrounds
Campground.find({}, function (err, camp) {
    if (err) {
        console.log("ERROR");
        console.log(err);
    } else {
        res.render("index", { campgrounds: camp });
    }
});

});

app.post("/campgrounds", function (req, res) {
var name = req.body.name;
var image = req.body.image;
var desc = req.body.description;
var newCampground = { name: name, image: image, description:desc };
//create new camp and save to database
Campground.create(newCampground, function (err, newlyCreated) {
    if (err) {
        console.log(err);
    } else {
        res.redirect("/campgrounds");
    }

});

});

app.get("/campgrounds/new", function (req, res) {
res.render("new.ejs");

});

//shows more info about camp
app.get("/campgrounds/:id", function (req, res) {
//find camp with provided id 
Campground.findById(req.params.id, function (err, foundCampground) {
    if (err) {
        console.log(err);
    } else {
        //render show template
        res.render("show", { campground: foundCampground });
    }
});

});


app.listen(PORT, process.env.IP, function () {
console.log("camp");
});

seeds.js ---->

var mongoose = require("mongoose");
var Campground = require("./models/campground");
var Comment = require("./models/comment");

var data = [
{
name: "something",
image: "image URL",
description: "blah blah bla1"
},

{
name: "something",
image: "image URL",
description: "blah blah bla2"
},

{
name: "something",
image: "image URL",
description: "blah blah bla3"
}
];

function seedDB() {
Campground.deleteMany({}, function(err) {
console.log("removed camps");
data.forEach(function(seed) {
  Campground.create(seed, function(err, data) {
    if (err) {
      console.log(err);
    } else {
      console.log("added campground");
      Comment.create(
        {
          text: "dubdabdubadah",
          author: "Homer"
        },
        function(err, comment) {
          if (err) {
            console.log(err);
          } else {
            campground.comments.push(comment);
            campground.save();
            console.log("Created new comment");
          }
        }
      );
    }
  });
});
});
}

module.exports = seedDB;

comment.js --->

var mongoose = require("mongoose");


var commentSchema= new mongoose.Schema({
text:String,
author:String
});


module.exports=mongoose.model("Comment", commentSchema);

campground.js ---->

var mongoose = require("mongoose");

var campgroundSchema = new mongoose.Schema({
name: String,
image: String,
description: String,
comments: [
{
  type: mongoose.Schema.Types.ObjectId,
  ref: "Comment"
}
]
});

module.exports = mongoose.model("Campground", campgroundSchema);

seeds.js 文件中此行发生错误 Campground.comments.push(comment); 它看起来像这样:

[nodemon] starting `node app.js`
camp
Database online
removed camps
added campground
added campground
added campground
events.js:183
throw er; // Unhandled 'error' event
^
ReferenceError: campground is not defined

当我将代码与练习文件代码进行比较时，我实际上无法理解这个问题 - 它是相同的。我唯一能想到的是 Mongoose 表达的版本或其他东西可能不相关或某些方法已弃用，但老实说不知道出了什么问题。我已经尝试解决它好几天了。有什么想法吗？

Answer 1

错误消息告诉您尚未定义名为 campground 的变量，这是正确的，因为您没有定义。

要解决此问题，请在 Campground.create 回调中将 data 更改为 campground:

Campground.create(seed, function(err, campground) {