public class ArtistRepository : IArtistRepository
{
	...
	private Nest.IElasticClient elastic_client;
	public ArtistRepository(..., Nest.IElasticClient elastic_client)
	{
		...
		this.elastic_client = elastic_client;
	}

	public async Task<Artist> InsertArtist(Artist artist)
	{
		...

		// Index
		var new_artist = ToDto(entity_artist);
		var index_status = await elastic_client.IndexDocumentAsync(new_artist);

		return new_artist;
	}

	public async Task<Artist> UpdateArtist(Artist artist)
	{
		...

		// Index
		var updated_artist = ToDto(artist_entity);
		await elastic_client.UpdateAsync<Artist>(updated_artist, u => u.Doc(updated_artist));

		return updated_artist;
	}

	public async Task DeleteArtist(int artist_id)
	{
		...

		// Index
		var artist_dto = ToDto(artist);
		await elastic_client.DeleteAsync<Artist>(artist_dto);
	}
}