Question:So I have a simple collection with an additional index on one field called “reactionId”. I then want to bulk-upsert multiple documents to that collection. The first one gets inserted, and then I get the error
This is the
Answer:The problem is that the index is defined on the property “reactionID” – notice the upper-case ID. In your model, the property is named “reactionId” with a lower-case d. Hence, when inserting, your document does not contain a value for the property that MongoDB expects. This leads to a null value for both documents in the index – hence the duplicate key violation.
If you drop the index and redefine it for “reactionId”, this insert should work.
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