使用Elasticsearch NEST C＃索引Json文档

Question

我是Elasticsearch的新手，想要了解如何使用NEST C＃在Jlastic文档之后创建索引和索引到Elasticsearch？

{
    "BookName": "Book1",
    "ISBN": "978-3-16-148410-0",
    "chapter" : [
        {
            "chapter_name": "Chapter1",
            "chapter_desc": "Before getting into computer programming, let us first understand computer programs and what they..."
        },
        {
            "chapter_name": "Chapter2",
            "chapter_desc": "Today computer programs are being used in almost every field, household, agriculture, medical, entertainment, defense.."
        },
        {
            "chapter_name": "Chapter3",
            "chapter_desc": "MS Word, MS Excel, Adobe Photoshop, Internet Explorer, Chrome, etc., are..."
        },
        {
            "chapter_name": "Chapter4",
            "chapter_desc": "Computer programs are being used to develop graphics and special effects in movie..."
        }
    ]
}

Answer 1

使用NEST创建索引非常简单

var client = new ElasticClient();
client.CreateIndex("index-name");

这将创建一个索引，其中包含为节点定义的默认分片数和副本数。

将表示为json的文档索引到索引中

var json = @"{
    ""BookName"": ""Book1"",
    ""ISBN"": ""978-3-16-148410-0"",
    ""chapter"" : [
        {
            ""chapter_name"": ""Chapter1"",
            ""chapter_desc"": ""Before getting into computer programming, let us first understand computer programs and what they...""
        },
        {
    ""chapter_name"": ""Chapter2"",
            ""chapter_desc"": ""Today computer programs are being used in almost every field, household, agriculture, medical, entertainment, defense..""
        },
        {
    ""chapter_name"": ""Chapter3"",
            ""chapter_desc"": ""MS Word, MS Excel, Adobe Photoshop, Internet Explorer, Chrome, etc., are...""
        },
        {
    ""chapter_name"": ""Chapter4"",
            ""chapter_desc"": ""Computer programs are being used to develop graphics and special effects in movie...""
        }
    ]
}";

var indexResponse = client.LowLevel.Index<string>("index-name", "type-name", json);

if (!indexResponse.Success)
    Console.WriteLine(indexResponse.DebugInformation);

在这里，我们通过使用低等级客户机索引JSON，提供NEST .LowLevel物业ElasticClient 。

要搜索索引文档

// refresh the index so that newly indexed documents are available
// for search without waiting for the refresh interval
client.Refresh("index-name");

var searchResponse = client.Search<dynamic>(s => s
    .Index("index-name")
    .Type("type-name")
    .Query(q => q
        .Match(m => m
            .Query("Photoshop")
            .Field("chapter.chapter_desc")
        )
    )
);

这将返回索引的文档。 Search<T>()使用的泛型类型参数dynamic意味着生成的文档将被反序列化为JObject类型。

当我们创建索引时，我们没有为我们的类型type-name指定映射，因此Elasticsearch从json文档的结构推断出映射。 这是动态映射 ，对于许多情况都很有用，但是，如果您知道要发送的文档的结构并且不会破坏性地更改它，那么您可以为该类型指定映射 。 在这个特定示例中执行此操作的优点是， chapter数组将被推断为object类型映射，但如果您想要搜索单个章节的章节名称和章节描述，那么您可能希望将chapter映射为nested类型 。