MongoServerError: E11000 duplicate key error collection
Error message
MongoServerError: E11000 duplicate key error collection
What broke
The error indicates that you tried to insert a document into a MongoDB collection where a unique index constraint was violated. This typically happens when you attempt to insert a document with a value for a field that must be unique, but that value already exists in the collection.
Why it broke
It broke because MongoDB enforces unique constraints on indexed fields. If you try to insert a document with a value for a unique field that already exists in the database, MongoDB will throw a duplicate key error to prevent data inconsistency.
How to fix
To fix this, you need to ensure that the value you are trying to insert for the unique field does not already exist in the collection. You can either modify the value to be unique or check for existing documents before the insert operation.
Code fix
const existingDoc = await collection.findOne({ uniqueField: newValue }); if (!existingDoc) { await collection.insertOne({ uniqueField: newValue }); }Explained by ErrorOracle
Prevention tip
You can either modify the value to be unique or check for existing documents before the insert operation.
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