Document dublication on a single submission

Caleb_Mucheru · 2024-04-30T17:47:25.585Z

I have a collection that should have a unique value in addition the id, like this

  book: { type: String, unique: true },

```When I check on the db, `book`  is not indexed, so I tried indexing it to ensure there is no value duplication of `book` but I get an error, even on unique values not in the database.

MongoServerError: E11000 duplicate key error collection: test.library index: book_1 dup key: { book: null }

michael_hoeller · 2024-05-02T07:53:21.272Z

Hello @Caleb_Mucheru

Caleb_Mucheru:

test.library index: book_1 dup key: { book: null }

Can you please review your code:

are you writing to the collection you want to?
it looks as if there is an index on ‘book’
also it seems that the duplication is on a ‘null’ value → please verify if you codes does what you want

In case you can not fix the issue by checking the above points, please provide more details.

Best, Michael

Caleb_Mucheru · 2024-05-02T13:57:36.558Z

I am writing to the collection I want to only when I remove an index on book. But this makes us have a two documents on a single submit, first with some fields, which some are empty and the second one which has all fields as expected.

michael_hoeller · 2024-05-02T20:23:03.847Z

Hello @Caleb_Mucheru
I am not sure if I understand correct:

you do one insert but you end up with two documents
when you add an unique index on book then you get the E11000 duplicate key error?

Can you please share your code?

Best, Michael