用 【NEST】 在C#中操作ElasticSearch

准备工作： VSCode开发环境，在终端控制台（Ctrl+~）输入命令 dotnet add package Nest 安装NEST包，安装好后打开项目的.csproj文件如下图。

一、索引数据：

using Nest;
using System;

namespace NetCoreFirst
{
    public class ImportES
    {
        public static string ElasticsearchMethod()
        {
            //1.通过es服务器 localhost:9200 来定义es client
            var node = new Uri("http://localhost:9200");
            var indexName = "esbot";
            var settings = new ConnectionSettings(node).DefaultIndex(indexName);
            var elastic = new ElasticClient(settings);
            
            //es服务器健康检查
            var res = elastic.ClusterHealth();
            Console.WriteLine(res.Status);

            //2.创建索引esbot
            if (!elastic.IndexExists(indexName).Exists)
            {
                var createIndexResponse = elastic.CreateIndex(indexName);
                var mappingBlogPost = elastic.Map<Resume>(s => s.AutoMap());
            }

            //3.构造数据
            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]
                };
                //4.导入数据到索引
                IIndexResponse bulkIndexResponse = elastic.Index(resume, p => p.Type(typeof(Resume)).Id(i).Refresh(null));
            }

            //5. 简单搜索
            var searchResult = elastic.Search<Resume>(sr => sr.Query(q => q.MatchAll()));
            // System.Console.WriteLine(searchResult.Hits.Count);
            // System.Console.ReadLine();
            var resumesCount = searchResult.Hits.Count.ToString();
            return resumesCount;
        }
    }
}

Resume类的定义：

using Nest;
using System;

namespace NetCoreFirst
{
    [ElasticsearchType(Name="candidate", IdProperty="Id")]
    public class Resume
    {
        [Text(Name="id", Index=false)]
        public Guid? Id { get; set; }

        [Text(Name="name", Index=true)]
        public string Name { get; set; }

        [Text(Name="age", Index=false)]
        public long Age { get; set; }

        [Text(Name="skills", Index=true)]
        public string Skills { get; set; }
    }
}

二、搜索数据

using Nest;
using System;

namespace NetCoreFirst
{
    public class SearchES
    {
        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> SearchNumber()
        {
            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> SearchString()
        {
            string queryStr = "";
            var searchResponse = elastic.Search<Bank>(es => es.Query(q => 
                    q.QueryString(qs => qs.Query(queryStr))));
            return searchResponse;
        }

        public static ISearchResponse<Bank> SearchField()
        {
            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;
        }
    }
}

Extension类和Bank类的定义

    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}
            };
        }
    }

    [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; }
    }

 *****************************

 *** Keep learning and growing. ***

 *****************************