c# ElasticSearch NEST 聚合：分组

Question

我的 ES NEST 查询有问题。它“创建组”，但项目列表为空。 我查找了示例并阅读了我发现的内容，但结果仍然是空的。

这是我的查询：

public partial class ElasticSearchService
    {
        private const string groupBySubCategoryKey = "SubCategoryKey";

        public async Task SiteMap()
        {
            ISearchResponse<AdvertisementObjectEntityExtended> result = await Client.SearchAsync<AdvertisementObjectEntityExtended>(s => s
               .Index(ElasticClientFactorySettings.AdvertisementObjectIndex)
               .Aggregations(agr =>
                agr.Terms(groupBySubCategoryKey,
                    g => g.Field(f =>
                        f.SubCategoryKey))));

            var r = result.Aggregations.Terms(groupBySubCategoryKey);
       

} }

public static class ElasticClientFactory
    {
        public static async Task<ElasticClient> ClientAsync(ElasticSearchSettings settings)
        {
            Uri uri = new Uri($"{settings.EndPoint}");

            ConnectionSettings ConnectionSettings = new ConnectionSettings(uri)
                                                    .DefaultIndex(ElasticClientFactorySettings.AdvertisementObjectIndex)
                                                    .DefaultMappingFor<AdvertisementObjectEntityExtended>(i => i.IndexName(ElasticClientFactorySettings.AdvertisementObjectIndex))
                                                    .EnableHttpCompression()
                                                    .PrettyJson();

            ElasticClient client =  new ElasticClient(ConnectionSettings);

            CreateIndexResponse createIndexResponse = await client.Indices.CreateAsync(ElasticClientFactorySettings.AdvertisementObjectIndex, c => c
                .Map<AdvertisementObjectEntityExtended>(m => m
                    .AutoMap()
                    .Properties(p => p
                         .Text(t => t.Name(n => n.Id).Analyzer(AnalyzerSettings.No))
                         .Text(t => t.Name(n => n.UserUniq).Analyzer(AnalyzerSettings.NotAnalyzed))
                         .Text(t => t.Name(n => n.Uniq).Analyzer(AnalyzerSettings.NotAnalyzed))
                         .Text(t => t.Name(n => n.MainCategoryKey).Analyzer(AnalyzerSettings.NotAnalyzed))
                         .Text(t => t.Name(n => n.SubCategoryKey).Analyzer(AnalyzerSettings.NotAnalyzed))
                         .Nested<List<string>>(n => n.Name(nn => nn.Images)
                        )
                    )
                )
            );

            return client;
        }
    }

public partial class ElasticSearchService : IElasticSearchService
    {
          public  ElasticSearchService(IOptions<ElasticSearchSettings> settings)
        {
            Client = ElasticClientFactory.ClientAsync(settings.Value).Result;
        }
    }

有什么想法吗？ 谢谢

Answer 1

问题是您的映射是文本类型。

要在文本字段上进行术语聚合，您需要为该字段打开 fielddata。 https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html#CO255-1

但您可能真正想要的是使用关键字字段而不是文本，它会自动与术语聚合一起使用。默认情况下不对其进行分析。因此，对映射的以下更改应该可以解决问题：

    .Keyword(t => t.Name(n => n.Id))
    .Keyword(t => t.Name(n => n.UserUniq))
    .Keyword(t => t.Name(n => n.Uniq))
    .Keyword(t => t.Name(n => n.MainCategoryKey))
    .Keyword(t => t.Name(n => n.SubCategoryKey))

现在我应该补充一点，如果图像是字符串列表，则不需要进行嵌套映射。字符串列表基本上与 elasticsearch 中的单个字符串相同，因此您可以执行以下操作：

    .Keyword(t => t.Name(n => nn.Images))