Nest：你应该如何处理 c# 中的亮点

Question

我正在尝试在索引中搜索“所有内容”以查找搜索词，并显示上下文并突出显示这些词。我得到了一组适当的文档返回，但无法弄清楚我应该如何处理代码中的突出显示。

此时我只是想将其转储为文字，并且下面的代码“有点像”有效，但它似乎并没有为每个文档突出显示，而且感觉不对。我找到了很多关于如何使用高亮进行查询的示例，但我还没有找到任何关于如何通过显示结果进行任何操作的示例。有什么建议？谢谢！

    var searchResults = client.Search<Document>(s => s.Query(qs => qs.QueryString(q => q.Query(stringsearch))).Highlight(h => h
            .PreTags("<b>")
            .PostTags("</b>")
            .OnFields(
              f => f
                .OnField("*")
                .PreTags("<em>")
                .PostTags("</em>")
            )
        ));

    Literal1.Text = "";

    foreach(var h in searchResults.Hits)
    {
        foreach(var hh in h.Highlights)
        {
            foreach(var hhh in hh.Value.Highlights)
            {
                Literal1.Text += hhh+@"<br>";
            }
        }
    }

Answer 1

编辑：下面的解决方案仅在 ElasticSearch 2.x 上测试，而不是 ElasticSearch 5.x/6.x

可以在searchResults.Highlights（所有精彩片段）或IHit<T>.Highlights 中访问精彩片段。

这是否符合您想要实现的目标？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using Elasticsearch.Net.ConnectionPool;
using Nest;

namespace ESTester
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            const string indexName = "testindex";
            var connectionSettings = new ConnectionSettings(new SingleNodeConnectionPool(new Uri("http://127.0.0.1:9200")));
            var client = new ElasticClient(connectionSettings);

            var existResponse = client.IndexExists(descriptor => descriptor.Index(indexName));
            if (existResponse.Exists)
                client.DeleteIndex(descriptor => descriptor.Index(indexName));

            // Making sure the refresh interval is low, since it's boring to have to wait for things to catch up
            client.PutTemplate("", descriptor => descriptor.Name("testindex").Template("testindex").Settings(objects => objects.Add("index.refresh_interval", "1s")));

            client.CreateIndex(descriptor => descriptor.Index(indexName));

            var docs = new List<Document>
            {
                new Document{Text = "This is the first document" },
                new Document{Text = "This is the second document" },
                new Document{Text = "This is the third document" }
            };

            var bulkDecsriptor = new BulkDescriptor().IndexMany(docs, (descriptor, document) => descriptor.Index(indexName));
            client.Bulk(bulkDecsriptor);

            // Making sure ES has indexed the documents
            Thread.Sleep(TimeSpan.FromSeconds(2));

            var searchDescriptor = new SearchDescriptor<Document>()
                .Index(indexName)
                .Query(q => q
                    .Match(m => m
                        .OnField(d => d.Text)
                        .Query("the second")))
                .Highlight(h => h
                    .OnFields(f => f
                        .OnField(d => d.Text)
                        .PreTags("<em>")
                        .PostTags("</em>")));

            var result = client.Search<Document>(searchDescriptor);

            if (result.Hits.Any())
            {
                foreach (var hit in result.Hits)
                {
                    Console.WriteLine("Found match: {0}", hit.Source.Text);
                    if (!hit.Highlights.Any()) continue;

                    foreach (var highlight in hit.Highlights.SelectMany(highlight => highlight.Value.Highlights))
                    {
                        Console.WriteLine("Found highlight: {0}", highlight);
                    }
                }
            }

            Console.WriteLine("Press any key to exit!");
            Console.ReadLine();
        }


    }

    internal class Document
    {
        public string Text { get; set; }
    }
}

为 cmets 编辑： 在此示例中，if(!hit.Highlights.Any()) continue; 没有真正的原因，除了安全之外，但如果您改为执行以下查询，则最终可能会得到没有高亮显示的命中：

    var docs = new List<Document>
    {
        new Document{Text = "This is the first document", Number = 1 },
        new Document{Text = "This is the second document", Number =500 },
        new Document{Text = "This is the third document", Number = 1000 }
    };

    var searchDescriptor = new SearchDescriptor<Document>()
        .Index(indexName)
        .Query(q => q
            .Bool(b => b
                .Should(s1 => s1
                    .Match(m => m
                        .Query("second")
                        .OnField(f => f.Text)),
                    s2 => s2
                        .Range(r =>r
                            .OnField(f => f.Number)
                            .Greater(750)))
                 .MinimumShouldMatch(1)))
        .Highlight(h => h
            .OnFields(f => f
                .OnField(d => d.Text)
                .PreTags("<em>")
                .PostTags("</em>")));

  internal class Document
  {
      public string Text { get; set; }
      public int Number { get; set; }
  }

在这种情况下，您可能会在范围查询中获得成功，但不会有任何亮点。

对于第 2 点，对我来说，我只是在快速观察、对象浏览器和 VS 中的 IntelliSense 中探索了从搜索中返回的对象。