CODEWITHSUNDEEP
ravendb
puco
puco

Reputation: 428

RavenDb: Join data with index

In my database I have a list of cases:

{ Id: 1, Owner: "guid1", Text: "Question1" }
{ Id: 2, Owner: "guid1", Text: "Question2" }
{ Id: 3, Owner: "guid2", Text: "Question3" }

When querying for data I would also like to have (in my index, result) number of cases each Owner has. So I created a map/reduce index on this collection:

public class RelatedCases
{
    public Guid Owner { get; set; }
    public int Count { get; set; }
}

public class RelatedCaseIndex : AbstractMultiMapIndexCreationTask<RelatedCases>
{
    public RelatedCaseIndex()
    {
        AddMap<CaseDocument> (c => c.Select(a => new { a.Owner, Count = 1 }));

        Reduce = result => result
            .GroupBy(a => a.Owner)
            .Select(a => new 
            { 
                Owner = a.Key, 
                Count = a.Sum(b => b.Count)
            });
    }
}

Now I just have no idea how to produce a query to include the data from the index. Based on documentation I tried something like:

session.Query<CaseDocument>().Customize(a => a.Include ...)

or TransformResults on a CaseIndex, which didn't work out properly.

I know I could just requery raven to get me list of all RelatedCases in a separate query, but I would like to do it in one round-trip.

Upvotes: 4

Views: 1421

Answers (2)

Daniel Lang
Daniel Lang

Reputation: 6839

You can't query for Cases and join the result with the map/reduce index on the fly. That's just not how it works, because every query will run against an index, so what you are really asking is joining two indexes. This is something you need to do upfront.

In other words - put all the information you want to query upon into your map/reduce index. You can then run the query on this index and .Include() the documents that you are also interested in.

Upvotes: 3

Paul Hinett
Paul Hinett

Reputation: 1981

I dont think you need a MultiMap index, a simple MapReduce index will suffice for this.

You can then query it like so:

session.Query<RelatedCases, RelatedCaseIndex>();

This will bring back a list of RelatedCases with the owner and count.

Upvotes: -1

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