Elasticsearch-net: Implementing IQueryable<T> with nest

[BjBlazkowicz]

Hello I am looking for ways to extend NEST.

Any guidelines?

[Mpdreamz]

Personally I am not a fan of IQueryable in any other context then databases (this blog post outlines other reasons).

Fully implementing IQueryable is a huge undertaking. Combining that fact with my own believes that it does not provide a great abstraction over elasticsearch's _search endpoint and all the features that exposes is the reason why I have never attempted to implement it for NEST.

That said the guys from CenturyLink have been working on such an implementation for a while now:

https://github.com/CenturyLinkCloud/ElasticLINQ

@damieng who works on that is an expert LINQ implementor (ex-microsoft employee who worked on LinqToSql, EF (code-first)) so I have no intention of going NIH!

I would love to investigate if ElasticLINQ could play nice using NEST .Search() but its not a high priority at the moment.

[BjBlazkowicz]

Thanks for your answer.

I can agree with you. But when it comes to polyglot persistence and basic CRUD operations IQueryable makes sense since most applications tend to use NHibernate/EF which in turn implements IQueryable. I've already looked at ElasticLINQ but there is no nice abstraction of IQueryable(like NHibernate have with NhQueryable for example). And for unit-testing it would be nice to have an IQueryable implementation.

[damieng]

Originally when I wrote ElasticLINQ NEST was an all-in-one but now the low-level and query levels have been split into separate projects it might be worth me seeing again if there is a good way to integrate.

[BjBlazkowicz]

Hello damieng,

I would love some kind of integration. Basically what I am looking for is the IQueryable implementation but I also need the power from NESTs .Search() and mapping capabilities.

I tried something of my own in one of my projects by using both NEST and ElasticLINQ. But I gave up on the fact that I had to deal with two clients and two libraries. It would be great if you could just pass a common client or something to ElasticQueryProvider thus giving you the power of ElasticLINQs IQueryable implementation.

[futurechan]

:+1:

[futurechan]

@Mpdreamz I did find this: http://www.elasticsearch.org/guide/en/elasticsearch/client/ruby-api/current/_persistence.html

Is implementing that in .net fundamentally the same problem?

[damieng]

No, implementing LINQ is basically translating expression trees that look a bit like SQL represented as methods into an as-close-as-possible elasticsearch DSL query.