How to stop insertion of duplicate documents in a mongodb collection?

@lew 

There are a few ways to prevent the insertion of duplicate documents in a MongoDB collection:

1. Use a unique index: You can create a unique index on one or more fields in your collection to enforce uniqueness. This will prevent any new documents with duplicate values in the indexed fields from being inserted.

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db.collection.createIndex({ field1: 1, field2: 1 }, { unique: true });

1. Use the $addToSet operator: If you are updating a document and want to add a new value to an array field, you can use the $addToSet operator. This will only add the new value if it does not already exist in the array.

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db.collection.update({ _id: ObjectId("document_id") }, { $addToSet: { arrayField: "new_value" } });

1. Use the upsert option: When performing an update operation, you can use the upsert option to insert a new document if no document matches the query criteria. This can help prevent the insertion of duplicate documents.

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db.collection.update({ field: "value" }, { field: "value" }, { upsert: true });

By utilizing these methods, you can effectively prevent the insertion of duplicate documents in a MongoDB collection.