ElasticSearch NEST 7.x append item to existing document object array property

Question

I'm looking for a way to append item to existing object list in index document.

I have object defined like this.

public class ElasticIndividual 
    {
        public string? Id{get; set;}        
        public IReadOnlyList<Participation>? ParticipationList{get; set;}
    }

I would like to update ParticipationList with new item. I know that i can override this list with list with added item but i don't have whole list and i don't want to perform search to get this list.

Is it possible to append item instead override?

Answer 1

Script update will help you with this.

var updateResponse = await elasticClient.UpdateAsync<EsDocument>(
    "1",
    u => u.Script(s => s
        .Source("ctx._source.participations.add(params.item)")
        .Params(objects => objects.Add("item", new Participation {Name = "new item"}))));

Below example app

class Program
{
    static async Task Main(string[] args)
    {
        string indexName = "my_index";
        var connectionSettings = new ConnectionSettings(new Uri("http://localhost:9200"));
        connectionSettings.DefaultIndex(indexName);
        var elasticClient = new ElasticClient(connectionSettings);

        await elasticClient.Indices.DeleteAsync(indexName);
        var indexResponse = await elasticClient.Indices.CreateAsync(indexName);

        var indexDocumentAsync = await elasticClient
            .IndexDocumentAsync(new EsDocument {Id = "1", Participations = new List<Participation> { new Participation { Name = "test" }}});

        var updateResponse = await elasticClient.UpdateAsync<EsDocument>(
            "1",
            u => u.Script(s => s
                .Source("ctx._source.participations.add(params.item)")
                .Params(objects => objects.Add("item", new Participation {Name = "new item"}))));
    }

    class EsDocument
    {
        public string Id { get; set; }
        public List<Participation> Participations { get; set; } = new List<Participation>();
    }

    class Participation
    {
        public string Name { get; set; }
    }
}

Update

Bulk operation for multiple docs can be constructed like below

var bulkResponse = await elasticClient.BulkAsync(b => b
    .Update<EsDocument>(u => u
        .Id("1")
        .Script(_ => new InlineScriptDescriptor("ctx._source.participations.add(params.item)")
            .Params(objects => objects.Add("item", new Participation {Name = "new item"}))))
    .Update<EsDocument>(u => u
        .Id("2")
        .Script(_ => new InlineScriptDescriptor("ctx._source.participations.add(params.item)")
            .Params(objects => objects.Add("item", new Participation {Name = "new item"}))))
);