C# NEST 5 Search with template

Elastic Stack Elasticsearch
2

You can create search templates by serializing searches created through the fluent API or object initializer syntax

var client = new ElasticClient();

var query = new SearchDescriptor<Question>()
    .Query(q => q
        .QueryString(m => m
            .Fields(f => f
                .Field(ff => ff.Title)
                .Field(ff => ff.Body)
            )
            .Query("{{query_string}}")
        )
    )
    .Aggregations(a => a
        .Terms("tags", ta => ta
            .Field(f => f.Tags)
        )
    );
    
var template = client.Serializer.SerializeToString(query);

client.PutSearchTemplate("template-name", ps => ps
    .Template(template)
);

var searchResponse = client.SearchTemplate<Question>(st => st
    .Index("posts")
    .Id("template-name")
    .Params(p => p
        .Add("query_string", "\"Jon Skeet\" AND \"Chuck Norris\"")  
    )
);

There are some methods within the fluent API that are constrained to take specific types e.g. From() and .Size() can only accept an int. You can also parameterize these with something like

var client = new ElasticClient();

var query = new SearchDescriptor<Question>()
    .Query(q => q
        .QueryString(m => m
            .Fields(f => f
                .Field(ff => ff.Title)
                .Field(ff => ff.Body)
            )
            .Query("{{query_string}}")
        )
    )
    .Aggregations(a => a
        .Terms("tags", ta => ta
            .Field(f => f.Tags)
        )
    );
    
var template = client.Serializer.SerializeToString(query);
var search = JObject.Parse(template);
search.Add("from", "{{from}}{{^from}}0{{/from}}");
search.Add("size", "{{size}}{{^size}}10{{/size}}");
template = client.Serializer.SerializeToString(search);

client.PutSearchTemplate("template-name", ps => ps
    .Template(template)
);

client.GetSearchTemplate("template-name");
    
var searchResponse = client.SearchTemplate<Question>(st => st
    .Index("posts")
    .Id("template-name")
    .Params(p => p
        .Add("query_string", "\"Jon Skeet\" AND \"Chuck Norris\"") 
        .Add("size", 50)
    )
);
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