MultiMatch with empty string on function score

[andreabalducci]

I'm upgrading from my old fork to the master and I've found that the MultiMatch with empty query produces

query: {}

instead of

query: { match_all : {} }

Is that right and we have to check the query string to change our QueryDescriptor or the multimatch should fallback on match_all ?

var s = new SearchDescriptor<ElasticsearchProject>().From(0).Size(10)
                .Query(q => q
                    .FunctionScore(fs => fs
                        .Query(qq => qq.MultiMatch(mm => mm.OnFields(f=>f.Country, f=>f.FloatValue).Query("")))
                        .Functions(
                            f => f.Gauss(x => x.StartedOn, d => d.Scale("42w")),
                            f => f.Linear(x => x.FloatValue, d => d.Scale("0.3")),
                            f => f.Exp(x => x.DoubleValue, d => d.Scale("0.5")),
                            f => f.BoostFactor(2)
                        )
                        .ScoreMode(FunctionScoreMode.sum)
                    )
                ).Fields(x => x.Content);

[Mpdreamz]

The default for conditionless queries is to fallback to an empty query (effectivily a match_all)

The master has a construct that allows you to control what to fallback to:

qq.Conditionless(c=>c
    .Query(cq=>cq.MultiMatch(mm => mm.OnFields(f=>f.Country, f=>f.FloatValue).Query("")))
    .Fallback(fq=>fq.MatchAll())
)

[andreabalducci]

An empty query object give me QueryParsingException (query malformed) on ES (still on ES 0.90.8).

Thanks!

[Mpdreamz]

Closed too quickly perhaps

Here's a ponder:

If the query inside functionscore is conditionless should the functionscore itself become conditionless or do a match_all?

Im inclined to say the first because thats how all the other conditionless queries bubble up. Love your thoughts on this @andreabalducci

PS: I see you use .Fields(). Elasticsearch changed the return type for fields to always return an array.

If you want to return a subset of your document while still mapping the result into result.Documents use this instead:

.Source(s=>s.Include(p=>p.Content))

[andreabalducci]

I'm switching from my function score fork, the old behaviour was match_all and I think it is was correct one.

For a LOB make sense, if you are Google Search maybe not.. I think is a business driven choice.

[andreabalducci]

Thanks for the .Fields() hint, that piece of code is from my old unit test on function score (still in the master).