CODEWITHSUNDEEP
node.jsmongoose
Muhib Ahmed
Muhib Ahmed

Reputation: 331

Why mongoose doesn't update?

I am learning Node.js. I am stuck in this Mongoose section because of this problem. findById(id) doesn't get my result back and update() doesn't work. I don't know why..

const mongoose = require("mongoose").set("debug", true);
mongoose
  .connect("mongodb://localhost/exercise")
  .then(() => console.log("Connected Successfully!"))
  .catch(err => console.error("Error: ", err.message));

const courseSchema = new mongoose.Schema({
  tags: [String],
  date: { type: Date, default: Date.now() },
  name: String,
  author: String,
  isPublished: Boolean,
  price: Number
});

const Courses = mongoose.model("Course", courseSchema);

async function updateCourse(id) {

  const course = await Courses.findById(id);
  course.author = "Muhib";
  const result = await course.save();
  console.log(result);
}

updateCourse("5a68fde3f09ad7646ddec17e");
//  console.log(Courses);

I get this error :

TypeError: Cannot set property 'author' of null

This is a snip of my record: enter image description here

btw find() works..

Thanks in advance :)

Upvotes: 1

Views: 426

Answers (2)

Chuong Tran
Chuong Tran

Reputation: 3441

Try to add try/catch. I'm not sure course..save() work without err

async function updateCourse(id) {
    try {
        const course = await Courses.findById(id);
        course.author = "Muhib";
        const result = await course.save();
        console.log(result);
    } catch (err) {
        console.log('err' + err);
    }
}

Edit 1: I found a solution a this post

async function updateCourse(id) {
    try {
        const course = await Courses.findById(id).exec();//fixed at here
        course.author = "Muhib";
        const result = await course.save();
        console.log(result);
    } catch (err) {
        console.log('err' + err);
    }
}

Another solution using findOneAndUpdate

try {
    var course = await Courses.findOneAndUpdate(
        {"id" : id},
        {$set: {"author" : "Muhib"}},
        {new : true}
    );
    res.status(200).json(course);
} catch (error) {
    console.log('err' + err);
}

Upvotes: 0

Muhib Ahmed
Muhib Ahmed

Reputation: 331


I solved the issue..
there is nothing wrong with the code...
first thing first WHY IT DOESN'T WORK

This problem occurs with the imported collections only. Because the imported collection contains _id property as a string

for example
{"_id":"5a6900fff467be65019a9001","tags":["angular","frontend"],"date":"2018-01-24T21:56:15.353Z","name":"Angular Course","author":"Mosh","isPublished":true,"price":15,"__v":0}

but what mongoose need is _id wrapped in ObjectId

SOLUTION when importing json object always make sure that _id is not a string but an object with a $oid as a key and _id as a value

for example
{"_id":"5a6900fff467be65019a9001","tags":["angular","frontend"],"date":"2018-01-24T21:56:15.353Z","name":"Angular Course","author":"Mosh","isPublished":true,"price":15,"__v":0}
should be
{"_id":{"$oid":"5c91a66d079f4807847fcde3"},"tags":["angular","frontend"],"date":"2018-01-24T21:56:15.353Z","name":"Angular Course","author":"Mosh","isPublished":true,"price":{"$numberInt":"15"},"__v":{"$numberInt":"0"}}

Upvotes: 2

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