具有DBRef的MongoDB / Morphia复合索引

Question

I haven't been able to find a definitive answer and I hope someone can help me. I want to create a compound index on an object that is "referenced" within Mongo. I'm obviously getting an error, which I'll describe below the code snippets.

@Entity
public class Address {
    public Address (String street, String City, String state, String zip) {
        this.street = street;
        this.city   = city;
        this.state  = state;
        this.zip    = zip;
    }

    // Getters and Setters

    @Id private ObjectId id;
    private String street;
    private String city;
    private String state;
    private String zip;
}

@Entity
@Indexes( @Index("location.city, name") )
public class Team {
    public Team (String sport, String name, Address location) {
        this.sport    = sport;
        this.name     = name;
        this.location = location;
    }

    // Getters and Setters

    @Id private ObjectId id;
    private String sport;
    private String name;
    @Reference private Address location;
    @Reference private List<Player> players;
}

And the error I'm getting is:

Exception in thread "main" com.google.code.morphia.query.ValidationException: Can not use dot-notation past 'location' could not be found in 'com.company.test.Team' while validating - location.city

So I guess my question is: am I getting this error because "Address" is a reference within "Team" or am I missing something else?

Thanks for any feedback.

Answer 1

If filtering by fields nested inside reference: field access for lists of objects in a class via morphia in mongodb

If filtering only by id of reference: .filter("location", new Key(Address.class, id))

Answer 2

Yes, that's why. Your location field is referencing a different collection - ie the "city" field in in a "Address" collection. You have the option of embedding Address inside team - this will save everything in the Team collection, and let you add your "location.city" index to the "Team" class/collection.