How to remove by index?

To remove an item from an array by index in a MongoDB document, you can use the $set operator along with the slice operator to create a new array without the specified index. However, MongoDB does not have a direct operator to remove an item by index, so you will need to use a combination of operations.

Here’s how you can do it:

1. Retrieve the document to get the current array.
2. Modify the array in your application code to remove the item at the specified index.
3. Update the document with the modified array.

Example

Suppose you have a document in a collection called users:

{
  "_id": ObjectId("1234567890abcdef12345678"),
  "hobbies": ["reading", "gaming", "coding"]
}

To remove the item at index 1 (which is "gaming"), you can do the following:

// Step 1: Find the document
const user = db.users.findOne({ _id: ObjectId("1234567890abcdef12345678") });

// Step 2: Remove the item at index 1
user.hobbies.splice(1, 1); // This removes the item at index 1

// Step 3: Update the document with the modified array
db.users.updateOne(
  { _id: ObjectId("1234567890abcdef12345678") },
  { $set: { hobbies: user.hobbies } }
);

After executing these commands, the hobbies array would be updated to:

{
  "hobbies": ["reading", "coding"]
}

Make sure to replace the document ID and array field name with your actual values.