app.js

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('/public', express.static('public'));
mongoose.connect('mongodb://127.0.0.1:27017/todolistDB', { useNewUrlParser: true }).then(() => {
  console.log("Connected to Database");
}).catch((err) => {
  console.log("Not Connected to Database ERROR! ", err);
});

const todolistSchema = new mongoose.Schema({
  name: String
});
const todolistModel = mongoose.model("todolistModel", todolistSchema);

const todolistDocument1 = new todolistModel({
  name: "Learning "
})

const todolistDocument2 = new todolistModel({
  name: "Web"
})

const todolistDocument3 = new todolistModel({
  name: "developmemnt"
})

const allDocuments = [todolistDocument1, todolistDocument2, todolistDocument3];

const listSchema = {
  name: String,
  items: [todolistSchema]
};

const List = mongoose.model("List", listSchema);

app.get("/", (req, res) => {

  todolistModel.find({}, function (err, foundItems) {

    if (foundItems.length === 0) {
      todolistModel.insertMany(allDocuments, function (err) {
        if (err) {
          console.log(err);
        }
        else {
          console.log("Successfully saved default items to DB.");
        }
      });
      res.redirect("/");
    }
    else {
      res.render("list", { listTitle: "Today", newListItems: foundItems });
    }
  });

});

app.post("/", (req, res) => {
  const itemName = req.body.newItem;
  const listName = req.body.list;

  const item = new todolistModel({
    name: itemName
  });
  if (listName === "Today") {
    item.save();
    res.redirect("/");
  }
  else {
    List.findOne({ name: listName }, function (err, foundList) {
      if (!err) {
        foundList.items.push(item);
        foundList.save();
        console.log(listName);
        res.redirect("/" + listName);
      }

    });
  }

});

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: allDocuments
        });
        list.save();
        res.redirect("/" + customListName);
      }
      else {

        //Show an existing list
        res.render("list", { listTitle: foundList.name, newListItems: foundList.items })
      }
    }
  });

});

app.post("/delete", (req, res) => {

  const checkedItemId = req.body.checkbox;
  const listName = req.body.listName;

  if (listName === "Today") {
    todolistModel.findByIdAndRemove(checkedItemId, function (err) {
      if (!err) {
        console.log("Removed Successfully !");
        res.redirect("/");
      }
    })
  } else {
    List.findOneAndUpdate({ name: listName }, { $pull: { items: { _id: checkedItemId } } }, function (err, foundList) {
      if (!err) {
        res.redirect("/" + listName)
      }
    })
  }
});


app.listen(4000, () => {
  console.log("Server started on port 4000");
})