How to delete or edit a mongodb document without an _id?

Question

Somehow, there is a document without an _id in my database. It can be pulled, but cannot be saved or deleted. The document looks something like the following:

{
  name: 'John Smith',
  key: 'abc123',
  data: [
    'Lorem ipsum',
    'dolor sic amet'
  ]
}

And my Schema looks like the following:

personSchema  = mongoose.Schema({
    name: String,
    data: { type: Array },
    key: String
})

Note, the key field is completely detached from the id and is used internally, and all other documents in the collection have an _id field.

The following code produces the error UnhandledPromiseRejectionWarning: MongooseError: No _id found on document!:

personSchema  = mongoose.Schema({
    name: String,
    data: { type: Array },
    key: String
});
Person = mongoose.model('entries', personSchema);
let entries = await Person.find({key: "abc123"});
let toDelete;
entries.forEach(entry => {
    if(!entry._id){
        toDelete = entry;
    }
});
toDelete.delete();

Answer 1

Your .delete() is asynchronous but you aren't handling it as asynchronous. Use .deleteOne() instead.

const mongoose = require('mongoose');
const personSchema = mongoose.Schema({
    name: String,
    data: { type: Array },
    key: String
});

const Person = mongoose.model('entries', personSchema);

async function deleteEntry() {
    try {
        let entries = await Person.find({ key: "abc123" });
        let toDelete;

        entries.forEach(entry => {
            if (!entry._id) {
                toDelete = entry;
            }
        });

        if (toDelete) {
            await toDelete.deleteOne();
        } else {
            console.log("No document found without an _id or all documents have an _id.");
        }
    } catch (error) {
        console.error("An error occurred:", error);
    }
}

deleteEntry();

Side note: It is possible to create documents without an _id. But I don't think that's what's going on in your situation.

const childSchema = new Schema({
  name: String
}, { _id: false });

const parentSchema = new Schema({
  children: [childSchema],
  familyName: String
});

const ParentModel = mongoose.model('Parent', parentSchema);

The parent document will have an _id, but the child document will not.