使用 NEST 为 elasticsearch 编写 DSL

Question

I am new to ElasticSearch. I want to write a simple aggregation query using NEST in asp.net. How to write this simple query

GET /_search
{
    "aggs" : {
        "genres" : {
            "terms" : { "field" : "genre" }
        }
    }
}

I started something like this:

var response = _connection.Get<ElasticClient>().Search<JObject>(s =>
{

}

Thanks

Answer 1

Started writing a comment, but maybe let's put it as an answer :)

Here are the docs for writing aggregations using NEST syntax.

As the example shows, for this sample aggregation:

{
  "aggs": {
    "name_of_child_agg": {
      "children": {
        "type": "commits"
      },
      "aggs": {
        "average_per_child": {
          "avg": {
            "field": "confidenceFactor"
          }
        },
        "max_per_child": {
          "max": {
            "field": "confidenceFactor"
          }
        },
        "min_per_child": {
          "min": {
            "field": "confidenceFactor"
          }
        }
      }
    }
  }
}

you can write this NEST fluent code:

s => s
.Aggregations(aggs => aggs
    .Children<CommitActivity>("name_of_child_agg", child => child
        .Aggregations(childAggs => childAggs
            .Average("average_per_child", avg => avg.Field(p => p.ConfidenceFactor))
            .Max("max_per_child", avg => avg.Field(p => p.ConfidenceFactor))
            .Min("min_per_child", avg => avg.Field(p => p.ConfidenceFactor))
        )
    )
)

Also, I don't think you want to use JObject type as POCO, this should put some light on how to use your custom type to map c# class into elasticsearch type. The reasoning behind: to have type responsible only for "communicating" with elasticsearch, so having JObject in this role may not the best option, as it's not a type created by you and it may evolve in the future in the way you don't want.