Create index in correct collection

Question

I annotate a document with @Index(unique = true) like so:

public class ADocumentWithUniqueIndex {
    private static final long serialVersionUID = 1L;

    @Indexed(unique = true)
    private String iAmUnique;

    public String getiAmUnique() {
        return iAmUnique;
    }

    public void setiAmUnique(String iAmUnique) {
        this.iAmUnique = iAmUnique;
    }
}

When saving the object, I specify a custom collection:

MongoOperations mongoDb = ...

mongoDb.save(document, "MyCollection");

As a result I get:

• A new document in "MyCollection"
• An index in the collection "ADocumentWithUniqueIndex"

How can I create the index in "MyCollection" instead without having to explicitly specify it in the annotation?

BACKGROUND:

• The default collection name is too ambiguous in our use case. We cannot guarantee, that there wouldn't be two documents with the same name but in different packages. So we added the package name to the collection.
• Mapping a document to a collection is dealt with in an infrastructure component.
• The implementation details like collection name etc. shouldn't leak into the individual documents.
• I understand this is a bit of an "abstraction on top of an abstraction" smell but required since we had to support MongoDb and Windows Azure blob storage. Not anymore though...

This seemed like a fairly standard approach to hide the persistence details in a infrastructure component. Any comments on the approach appreciated as well.

Answer 1

It's kind of unusual to define the collection for an object to be stored and then expect the index annotations to work. There's a few options you have here:

1. Use @Document on ADocumentWithUniqueIndex and configure the collection name manually. This will cause all objects of that class to be persisted into that collection of course.

2. Manually create indexes via MongoOperations.indexOps() into the collections you'd like to use. This would be more consistent to your approach of manually determining the collection name during persistence operations.