錯誤：拋出錯誤；// 未處理的“錯誤”事件
TypeError：無法在 C:\Users\shiva\Desktop\Web Development\todolist\app.js:105:17 讀取 null 的屬性（讀取“專案”）
在第一個 app.post 方法 -> else 陳述句中出現錯誤。堅持了將近一天。ps：由于我更改了資料庫鏈接，代碼可能無法運行
const express = require("express");
const bodyParser = require("body-parser");
const mongoose = require("mongoose");
const _ = require("lodash");
const app = express();
app.set('view engine', 'ejs');
app.use(bodyParser.urlencoded({extended: true}));
app.use(express.static("public"));
mongoose.connect("mongodb srv://adminshivam:[email protected]/todolistDB");
const itemsSchema = {
name: String
};
const Item = mongoose.model("Item", itemsSchema);
const item1 = new Item({
name: "Welcome to your todolist!"
});
const item2 = new Item({
name: "Hit the button to add a new item."
});
const item3 = new Item({
name: "<-- Hit this to delete an item."
});
const defaultItems = [item1, item2, item3];
const listSchema = {
name: String,
items: [itemsSchema]
};
const List = mongoose.model("List", listSchema);
app.get("/", function(req, res) {
Item.find({}, function(err, foundItems){
if (foundItems.length === 0) {
Item.insertMany(defaultItems, function(err){
if (err) {
console.log(err);
} else {
console.log("Successfully savevd default items to DB.");
}
});
res.redirect("/");
} else {
res.render("list", {listTitle: "Today", newListItems: foundItems});
}
});
});
app.get("/:customListName", function(req, res){
const customListName = _.capitalize(req.params.customListName);
List.findOne({name: customListName}, function(err, foundList){
if (!err){
if (!foundList){
//Create a new list
const list = new List({
name: customListName,
items: defaultItems
});
list.save();
res.redirect("/" customListName);
} else {
//Show an existing list
res.render("list", {listTitle: foundList.name, newListItems: foundList.items});
}
}
});
});
app.post("/", function(req, res){
const itemName = req.body.newItem;
const listName = req.body.list;
const item = new Item({
name: itemName
});
if (listName === "Today"){
item.save();
res.redirect("/");
} else {
List.findOne({name: listName}, function(err, foundList){
foundList.items.push(item);
foundList.save();
res.redirect("/" listName);
});
}
});
app.post("/delete", function(req, res){
const checkedItemId = req.body.checkbox;
const listName = req.body.listName;
if (listName === "Today") {
Item.findByIdAndRemove(checkedItemId, function(err){
if (!err) {
console.log("Successfully deleted checked item.");
res.redirect("/");
}
});
} else {
List.findOneAndUpdate({name: listName}, {$pull: {items: {_id: checkedItemId}}}, function(err, foundList){
if (!err){
res.redirect("/" listName);
}
});
}
});
app.get("/about", function(req, res){
res.render("about");
});
app.listen(3000, function() {
console.log("Server started on port 3000");
});
上面代碼的錯誤鏈接
foundList.items.push(item);
串列.ejs
<%- include("header") -%>
<div class="box" id="heading">
<h1> <%= listTitle %> </h1>
</div>
<div >
<% newListItems.forEach((listItem) => { %>
<form action="/delete" method="post">
<div >
<input type="checkbox" name="checkbox" value="<%= listItem._id %>" onChange="this.form.submit()">
<p><%= listItem.name %></p>
</div>
<input type="hidden" name="listName" value="<%= listTitle %>"></input>
</form>
<% });%>
<form action="/" method="post">
<input type="text" name="newItem" placeholder="New Item" autocomplete="off">
<button type="submit" name="list" value="<%= listTitle %> "> </button>
</form>
</div>
<%- include("footer") -%>
uj5u.com熱心網友回復：
問題似乎出在您的架構上，您沒有以正確的方式進行操作，而是將物件傳遞給moongose.model這樣的：
const itemsSchema = {
name: String
};
const Item = mongoose.model("Item", itemsSchema);
您應該使用來自 mongoose 的類創建一個模式Schema，因此請嘗試以下操作：
const mongoose = require("mongoose");
const { Schema } = mongoose
const itemsSchema = new Schema({
name: {type: String, required: true}
})
const Item = mongoose.model("Item", itemsSchema)
并在您listSchema執行以下操作：
// removed const defaultItems = [item1, item2, item3];
const listSchema = new Schema({
name: {type: String, required: true},
// define an array of id that references the Item schema
items: [{type: ObjectId, ref: "Item", required: true, default: [] }]
});
const List = mongoose.model("List", listSchema);
// the object named as list1 will contain a reference to id of item1, item2 and item3.
const list1 = new List({name: "list1", items: [item1._id, item2._id, item3._id]}).save()
再往上，在你的post api：
app.post("/", async function(req, res){
const itemName = req.body.newItem;
const listName = req.body.list;
try {
const item = new Item({ name: itemName });
if (listName === "Today") {
await item.save();
res.redirect("/");
} else {
// save the item id to items field from list schema
const list = await List.findOne({ name: listName })
list.items.push(item._id)
await list.save()
// don't make a redirect within the database query
res.redirect("/" listName);
}
} catch(err) {
// If some error was threw handle it here
// you can handle mongoose errors as follow:
if(err instanceof mongoose.Error) {
// use a custom message or err.message
res.status(500).json({message: "error with Db"})
}
res.status(500).json({message: "something went wrong"})
}
});
請參閱檔案以了解更多資訊，因為您正在使用模式之間的參考，我建議您查看populate 方法，因為將來您可能會需要它。還可以查看來自 mongoose 的可用查詢，您需要的幾乎所有內容都在檔案中。希望我對你有所幫助！
轉載請註明出處，本文鏈接：https://www.uj5u.com/qianduan/468127.html