Elasticsearch使用系列-.NET6對接Elasticsearch

包子wxl發表於2022-02-14
Elasticsearch

Elasticsearch使用系列-ES簡介和環境搭建

Elasticsearch使用系列-ES增刪查改基本操作+ik分詞

Elasticsearch使用系列-基本查詢和聚合查詢+sql外掛

Elasticsearch使用系列-.NET6對接Elasticsearch

先安裝nuget包

Install Package NEST

 

1.建立索引

先建一個Model用於對映索引

 /// <summary>
    /// 商品資訊
    /// </summary>
    public class OrderInfo
    {
        public string Id { get; set; } 
        public DateTime CreateTime { get; set; }
        public string Name { get; set; }
        public string GoodsName { get; set; }

        public string Status { get; set; }
    }

1.1自動轉換ES型別

    /// <summary>
    /// ES操作
    /// </summary>
    public class ESService
    {
        //建立連線client
        private static ElasticClient _client = new ElasticClient(new Uri("http://192.168.101.13:9200"));

        //建立索引mapping
        public void Mapping()
        {
            //建立索引，自動轉換型別，order為索引名稱
            _client.Indices.Create("order", c => c
             .Map<OrderInfo>(m => m
             .AutoMap()
             ));

        }
    }

得到order的mapping的為

 "order" : {
    "mappings" : {
      "properties" : {
        "createTime" : {
          "type" : "date"
        },
        "goodsName" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "id" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "name" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "status" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        }
      }
    }
  }

1.2通過特性指定欄位的ES型別

 　　/// <summary>
    /// 商品資訊
    /// </summary>
    public class OrderInfo
    {
        [Keyword(Name="Id")]
        public string Id { get; set; }
        [Date(Name = "CreateTime")]
        public DateTime CreateTime { get; set; }
        [keyword]
        public string Name { get; set; }
        [Text]
        public string GoodsName { get; set; }

        public string Status { get; set; }
    }

通過給欄位標特性指定欄位轉換成的ES型別，型別有：Text，Keyword，Number，Boolean，Date等

2.插入資料

 2.1.插入單條資料

 /// <summary>
        /// 插入單條
        /// </summary>
        public void Insert()
        {
            var order = new OrderInfo()
            {
                Id = Guid.NewGuid().ToString(),
                CreateTime = DateTime.Now,
                Name = "張三",
                GoodsName = "手機P50",
                Status = "購物車"
            };
            var indexResponse = _client.Index(order, i => i.Index("order"));
            if(!indexResponse.IsValid)
            {
                //插入失敗處理
            }
        }

2.2批量插入資料

/// <summary>
        /// 插入多條
        /// </summary>
        public void InsertList()
        {
            var orders = new List<OrderInfo>();
            for(int i=1;i<=10;i++)
            {
                orders.Add(new OrderInfo()
                {
                    Id = Guid.NewGuid().ToString(),
                    CreateTime = DateTime.Now,
                    Name = "王五" + i,
                    GoodsName="冰箱"+i，
    　　　　　　　　　 Status="待付款"
                });
            }

            var bulkIndexResponse = _client.Bulk(b => b
              .Index("order")
              .IndexMany(orders));
            if(!bulkIndexResponse.IsValid)
            {
                //失敗處理
            }
           
        }

3.資料查詢

3.1查詢全部資料

/// <summary>
        /// 查詢全部
        /// </summary>
        public void SearchAll()
        {
            QueryContainer query = new QueryContainer();
            query = new MatchAllQuery(); //查詢全部

             var searchResponse = _client.Search<OrderInfo>(s => s
              .Index("order")
              .Query(q=>query)
              );
            //獲取查詢資料
            List<OrderInfo> datas =searchResponse.Documents.ToList();
        }

3.2分頁查詢

 /// <summary>
        /// 分頁查詢
        /// </summary>
        public void SearchPage()
        {
            QueryContainer query = new QueryContainer();
            query = new MatchAllQuery(); //查詢全部
            int pageIndex = 1;
            int pageSize = 5;

            var searchResponse = _client.Search<OrderInfo>(s => s
             .Index("order")
             .Query(q => query)
             .From((pageIndex-1)*pageSize) //從第幾條索引開始
             .Size(pageSize) //返回多少條
             );
            //獲取查詢資料
            List<OrderInfo> datas = searchResponse.Documents.ToList();
        }

3.3遊標查詢Scroll

為了避免深度分頁效能問題，ES預設From&Size的查詢只能查詢到10000條之前的資料，要查詢10000條之後的資料，需要用到遊標查詢

第一次查詢產生scrollId，後面的查詢只需要scrollId就可以記住原來的條件和查詢位置，往後滾動查詢

  /// <summary>
        /// 遊標查詢
        /// </summary>
        public void SearchScroll()
        {
            MatchAllQuery query = new MatchAllQuery();//查詢全部
            int pageSize = 5;

            var searchResponse = _client.Search<OrderInfo>(s => s
             .Index("order")
             .Query(q => query)
             .Size(pageSize) //一次返回多少條
             .Scroll("10s") //scrollId有效時間
             );
            //獲取查詢資料
            List<OrderInfo> datas = searchResponse.Documents.ToList();

           string scrollId = searchResponse.ScrollId;//遊標Id
            //後面的查詢只需要用scrollId查詢
           var searchResponse2 = _client.Scroll<OrderInfo>("10s", scrollId);
           
            List<OrderInfo> datas2 = searchResponse2.Documents.ToList();

        }

3.4條件查詢

 /// <summary>
        /// 條件查詢
        /// </summary>
        public void SearchWhere()
        {
            //查詢name=王五
            var searchResponse = _client.Search<OrderInfo>(s => s
            .Index("order")
                  .Query(q => q.Term(q=>q.Name, "王五1"))
          );
            //獲取查詢資料
            List<OrderInfo> datas = searchResponse.Documents.ToList();
        }

3.5條件or查詢

/// <summary>
        /// 條件or查詢
        /// </summary>
        public void SearchOr()
        {
           //查詢 name='王五1'or name='王五二'
            var searchResponse = _client.Search<OrderInfo>(s => s
              .Index("order")
              .Query(q => q
              .Term(o=>o.Name,"王五1")||q
              .Term(o=>o.Name,"王五2"))
            );
            //獲取查詢資料
            List<OrderInfo> datas = searchResponse.Documents.ToList();
        }

 3.6條件And查詢

 /// <summary>
        /// 條件and查詢
        /// </summary>
        public void SearchAnd()
        {
            //查詢 name='王五1'or status='待付款'
            var searchResponse = _client.Search<OrderInfo>(s => s
              .Index("order")
              .Query(q => q
              .Term(o => o.Name, "王五1") && q
              .Term("status.keyword", "待付款")) //因為status是text+keyword型別，查詢欄位要加上".keyword"
            );
            //獲取查詢資料
            List<OrderInfo> datas = searchResponse.Documents.ToList();
        }

 3.7聚合統計查詢

  /// <summary>
        /// 聚合查詢統計
        /// </summary>
        public void SearchAggs()
        {
            //求員工年齡平均值和最大年齡
            var searchResponse = _client.Search<object>(s => s
              .Index("employee")
              .Size(0) //不返回源資料
              .Aggregations(aggs=>aggs
              .Average("avgage",avg=>avg.Field("age"))
              .Max("maxage",max=>max.Field("age"))
            ));
            var datas = searchResponse.Aggregations ;
           

        }

3.8聚合分組查詢

 /// <summary>
        /// 聚合分組查詢
        /// </summary>
        public void SearchAggsGroup()
        {
            //求員工年齡平均值和最大年齡
            var searchResponse = _client.Search<object>(s => s
              .Index("employee")
              .Size(0) //不返回源資料
              .Aggregations(aggs => aggs
            .Terms("jobgroup", group => group.Field("job"))
            ));
            var datas = searchResponse.Aggregations;

        }

 4.sql語句查詢

需要安裝sql外掛，參照前一篇文章，這裡通過rest api向ES發起sql語句的查詢

建一個引數類和HttpHelper

    public class QueryParam
    {
        public string query { get; set; }
    }
    public class HttpHelper
    {
        private static HttpClient _httpClient = new HttpClient();
        public static string Post(QueryParam param, string url)
        {
            HttpContent content = new StringContent(JsonConvert.SerializeObject(param));
            content.Headers.ContentType= new MediaTypeHeaderValue("application/json");
            string result = _httpClient.PostAsync(url, content).Result.Content.ReadAsStringAsync().Result;
            content.Dispose();
            return result;
        }
    }

向ES發起sql語句查詢

　　　　　/// <summary>
        /// sql語句查詢
        /// </summary>
        public void SearchSql()
        {
            QueryParam queryParam = new QueryParam();
            queryParam.query = "select * from employee where job='java'";
            string url = "http://192.168.101.13:9200/_xpack/sql?format=csv";
            var result = HttpHelper.Post(queryParam, url);
            Console.WriteLine(result);
        }

 

 

 

 這裡查詢返回的格式為csv格式，資料需要自己解析成物件

 

 更多用法參考NEST官網：https://www.elastic.co/guide/en/elasticsearch/client/net-api/current/index.html

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