利用NEST2.0 在C#中操作Elasticsearch

本文从两个方面简单描述下NEST的用法：

• 索引数据
• 搜索数据

注意我索引数据和搜索数据是两个不同的例子。没有衔接关系

NOTE :NEST操作es，存储数据的类型应该是要已知的

准备工作：需要在visual studio 用NuGet 搜索 NEST，下载NEST 2.3即可

一、索引数据：

下段代码有如下要点：

1.通过es服务器 localhost:9200来定义es client

2.导入前通过定义字段类型的类，自动mapping,如下：

var mappingBlogPost = elastic.Map(s => s.AutoMap());

3.构造数据

4.导入数据 elasticsearch.Index

using Nest;using System;using System.Linq;namespace BotEsNest{    public class ImportEs    {        public static string  ElasticsearchMethod()        {            var node = new Uri("http://localhost:9200");            var indexName = "esbot";            var settings = new ConnectionSettings(node).DefaultIndex(indexName);            var elastic = new ElasticClient(settings);            //            var res = elastic.ClusterHealth(); //            Console.WriteLine(res.Status);            //            if (!elastic.IndexExists(indexName).Exists)            {                var createIndexResponse = elastic.CreateIndex(indexName);                var mappingBlogPost = elastic.Map<Resume>(s => s.AutoMap());                //Console.WriteLine("createIndexResponse=" + createIndexResponse.IsValid);                //Console.WriteLine("mappingBlogPost=" + mappingBlogPost.IsValid);            }            //            string[] nameArray = { "Cody", "Blake", "Dennis", "Evan ", "Harris", "Jason ", "Lambert ", "Louis ", "Milton ", "Cody" };            string[] skillArray = { "c#", "c++", "java", "python", "php", "Linux", "ruby", "matlab", "perl", "powershell" };            long[] ageRange = { 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 };            for (int i = 0; i < 10; i++)            {                var resume = new Resume                {                    Id = Guid.NewGuid(),                    Name = nameArray[i],                    Age = ageRange[i],                    Skills = "My skill is Azure and " + skillArray[i]                };                IIndexResponse bulkIndexReponse = elastic.Index(resume, p => p                   .Type(typeof(Resume))                   .Id(i)                   .Refresh());            }            var searchResult = elastic.Search<Resume>(sr => sr                                                                                        .Query(q => q.MatchAll())                                                                                  );            //Console.WriteLine(searchResult.Hits.Count());            //Console.ReadLine();            var resumesCount = searchResult.Hits.Count().ToString();            return resumesCount;        }    }}

搜索返回的信息都包含在searchResult中。索引esbot也已经创建。可以通过sense或者curl进行查看

Resume 这个类要提前根据数据类型进行定义：

using System;namespace BotEsNest{    using Nest;    [ElasticsearchType(Name = "candidate", IdProperty = "Id")]    public class Resume    {        [String(Name = "id", Index = FieldIndexOption.NotAnalyzed)]        public Guid? Id { get; set; }        [String(Name = "name", Index = FieldIndexOption.Analyzed)]        public string Name { get; set; }        [String(Name = "age", Index = FieldIndexOption.NotAnalyzed)]        public long Age { get; set; }        [String(Name = "skills", Index = FieldIndexOption.Analyzed)]        public string Skills { get; set; }    }}

二、搜索数据

1.此处我数据源是es官方的bank实例，并提前导入

2.搜索数据的关键在于用lambda表达式构造搜索内容

下段代码是为了动态定制参数所做

using System;using System.Collections.Generic;using System.Linq;using System.Linq.Expressions;using System.Web;namespace BotEsNest.Ext{    public class Extension    {        public static Dictionary<string, Expression<Func<Resume, object>>> ResumeDIctionary()        {            return new Dictionary<string, Expression<Func<Resume, object>>>            {                { "age",p=>p.Age},                { "name",p=>p.Name}            };        }        public static Dictionary<string, Expression<Func<Bank, object>>> BankDictionary()        {            return new Dictionary<string, Expression<Func<Bank, object>>>            {                { "account_number",p=>p.account_number},                { "age",p=>p.age},                {"balance",p=>p.balance},            };        }    }}

3.定义搜索类型：

using Nest;namespace BotEsNest{    [ElasticsearchType(Name = "account", IdProperty = "Id")]    public class Bank    {        public long account_number { get; set; }        public string address { get; set; }        public long age { get; set; }        public long balance { get; set; }        public string city { get; set; }        public string email { get; set; }        public string employer { get; set; }        public string firstname { get; set; }        public string gender { get; set; }        public string lastname { get; set; }        public string state { get; set; }    }}

4.进行搜索：

我大概写了三种搜索方式：
比如：返回存款在40000到40100的人，返回数据中带有Miltoon的人，返回数据中带有35的人
返回结构存在searchResponse中，未作继续处理，有兴趣的可以继续优化处理

using System;using Nest;using BotEsNest.Ext;namespace BotEsNest{    public class Elasticsearch    {        public static string indexName = "bank";        public static Uri node = new Uri("http://localhost:9200");        public static ConnectionSettings settings = new ConnectionSettings(node).DefaultIndex(indexName);        public static ElasticClient elastic = new ElasticClient(settings);        public static ISearchResponse<Bank> esSearchNumber()        {            //            string dictionaryKey = "balance";            var dictionary = Extension.BankDictionary();            var rangeField = dictionary[dictionaryKey];            var gt = 40000;            var lt = 40100;            var searchResponse = elastic.Search<Bank>(es => es                                                                                                  .Query(q => q                                                                                                        .Range(r => r                                                                                                            .Name("")                                                                                                            .Field(rangeField)                                                                                                                .GreaterThan(gt)                                                                                                                .LessThan(lt)                                                                                                                .Boost(2.0))));            return searchResponse;        }        public static ISearchResponse<Bank>esSearchString()        {            string quertStr = "Miltoon";            var searchResponse = elastic.Search<Bank>(es => es                                                                                      .Query(q =>                                                                                                                                                                            q.QueryString(qs => qs.Query(quertStr))                                                                                                                ));            return searchResponse;        }        public static ISearchResponse<Bank>esSearchField()        {            string queryStr = "35";            string dictionaryKey = "age";            var dictionary = Extension.BankDictionary();            var rangeField = dictionary[dictionaryKey];            var searchResponse = elastic.Search<Bank>(es => es                                            .Query(q => q                                                    .Match(m => m                                                        .Field(rangeField)                                                            .Query(queryStr))));            return searchResponse;        }    }}