execute an elasticsearch aggregation query in csharp

main.cs
var response = await client.SearchAsync<Document>(s => s
    .Aggregations(a => a
        .Terms("group_by_field", t => t
            .Field(p => p.FieldToAggregate)
        )
        .Aggregations(b => b
            .Sum("sum_field", sm => sm
                .Field(p => p.FieldToSum)
            )
        )
    )
)
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In the above code block, the client object represents an instance of the ElasticClient class provided by the NEST library, which is a popular Elasticsearch client for C#.

The SearchAsync() method is used to execute a search query against Elasticsearch. The Document type parameter represents the POCO (Plain Old CLR Object) that represents the document type being searched.

The Aggregations() method is used to specify one or more aggregation queries. In the example, we specify a Terms aggregation to group the documents by a particular field (FieldToAggregate). We also specify a nested Sum aggregation to calculate the sum of the values in a different field (FieldToSum) for each group.

The await keyword is used to asynchronously wait for the search response to be returned from Elasticsearch. The response can then be inspected to retrieve the aggregation results.