1. 操作ElasticSearch

1.1.1. elastic client

我们使用第三方库https://github.com/olivere/elastic 来连接ES并进行操作。

注意下载与你的ES相同版本的client，例如我们这里使用的ES是7.2.1的版本，那么我们下载的client也要与之对应为github.com/olivere/elastic/v7。

使用go.mod来管理依赖：

  1.     require (
  2.         github.com/olivere/elastic/v7 v7.0.4
  3.     )

简单示例：

  1. package main
  3. import (
  4.     "context"
  5.     "fmt"
  7.     "github.com/olivere/elastic/v7"
  8. )
  10. // Elasticsearch demo
  12. type Person struct {
  13.     Name    string `json:"name"`
  14.     Age     int    `json:"age"`
  15.     Married bool   `json:"married"`
  16. }
  18. func main() {
  19.     client, err := elastic.NewClient(elastic.SetURL("http://127.0.0.1:9200"))
  20.     if err != nil {
  21.         // Handle error
  22.         panic(err)
  23.     }
  25.     fmt.Println("connect to es success")
  26.     p1 := Person{Name: "lmh", Age: 18, Married: false}
  27.     put1, err := client.Index().
  28.         Index("user").
  29.         BodyJson(p1).
  30.         Do(context.Background())
  31.     if err != nil {
  32.         // Handle error
  33.         panic(err)
  34.     }
  35.     fmt.Printf("Indexed user %s to index %s, type %s\n", put1.Id, put1.Index, put1.Type)
  36. }

示例2：

  1. package main
  3. import (
  4.     "context"
  5.     "fmt"
  6.     "log"
  7.     "os"
  8.     "reflect"
  10.     "gopkg.in/olivere/elastic.v7" //这里使用的是版本5，最新的是6，有改动
  11. )
  13. var client *elastic.Client
  14. var host = "http://127.0.0.1:9200/"
  16. type Employee struct {
  17.     FirstName string   `json:"first_name"`
  18.     LastName  string   `json:"last_name"`
  19.     Age       int      `json:"age"`
  20.     About     string   `json:"about"`
  21.     Interests []string `json:"interests"`
  22. }
  24. //初始化
  25. func init() {
  26.     errorlog := log.New(os.Stdout, "APP", log.LstdFlags)
  27.     var err error
  28.     client, err = elastic.NewClient(elastic.SetErrorLog(errorlog), elastic.SetURL(host))
  29.     if err != nil {
  30.         panic(err)
  31.     }
  32.     info, code, err := client.Ping(host).Do(context.Background())
  33.     if err != nil {
  34.         panic(err)
  35.     }
  36.     fmt.Printf("Elasticsearch returned with code %d and version %s\n", code, info.Version.Number)
  38.     esversion, err := client.ElasticsearchVersion(host)
  39.     if err != nil {
  40.         panic(err)
  41.     }
  42.     fmt.Printf("Elasticsearch version %s\n", esversion)
  44. }
  46. /*下面是简单的CURD*/
  48. //创建
  49. func create() {
  51.     //使用结构体
  52.     e1 := Employee{"Jane", "Smith", 32, "I like to collect rock albums", []string{"music"}}
  53.     put1, err := client.Index().
  54.         Index("megacorp").
  55.         Type("employee").
  56.         Id("1").
  57.         BodyJson(e1).
  58.         Do(context.Background())
  59.     if err != nil {
  60.         panic(err)
  61.     }
  62.     fmt.Printf("Indexed tweet %s to index s%s, type %s\n", put1.Id, put1.Index, put1.Type)
  64.     //使用字符串
  65.     e2 := `{"first_name":"John","last_name":"Smith","age":25,"about":"I love to go rock climbing","interests":["sports","music"]}`
  66.     put2, err := client.Index().
  67.         Index("megacorp").
  68.         Type("employee").
  69.         Id("2").
  70.         BodyJson(e2).
  71.         Do(context.Background())
  72.     if err != nil {
  73.         panic(err)
  74.     }
  75.     fmt.Printf("Indexed tweet %s to index s%s, type %s\n", put2.Id, put2.Index, put2.Type)
  77.     e3 := `{"first_name":"Douglas","last_name":"Fir","age":35,"about":"I like to build cabinets","interests":["forestry"]}`
  78.     put3, err := client.Index().
  79.         Index("megacorp").
  80.         Type("employee").
  81.         Id("3").
  82.         BodyJson(e3).
  83.         Do(context.Background())
  84.     if err != nil {
  85.         panic(err)
  86.     }
  87.     fmt.Printf("Indexed tweet %s to index s%s, type %s\n", put3.Id, put3.Index, put3.Type)
  89. }
  91. //删除
  92. func delete() {
  94.     res, err := client.Delete().Index("megacorp").
  95.         Type("employee").
  96.         Id("1").
  97.         Do(context.Background())
  98.     if err != nil {
  99.         println(err.Error())
  100.         return
  101.     }
  102.     fmt.Printf("delete result %s\n", res.Result)
  103. }
  105. //修改
  106. func update() {
  107.     res, err := client.Update().
  108.         Index("megacorp").
  109.         Type("employee").
  110.         Id("2").
  111.         Doc(map[string]interface{}{"age": 88}).
  112.         Do(context.Background())
  113.     if err != nil {
  114.         println(err.Error())
  115.     }
  116.     fmt.Printf("update age %s\n", res.Result)
  118. }
  120. //查找
  121. func gets() {
  122.     //通过id查找
  123.     get1, err := client.Get().Index("megacorp").Type("employee").Id("2").Do(context.Background())
  124.     if err != nil {
  125.         panic(err)
  126.     }
  127.     if get1.Found {
  128.         fmt.Printf("Got document %s in version %d from index %s, type %s\n", get1.Id, get1.Version, get1.Index, get1.Type)
  129.     }
  130. }
  132. //搜索
  133. func query() {
  134.     var res *elastic.SearchResult
  135.     var err error
  136.     //取所有
  137.     res, err = client.Search("megacorp").Type("employee").Do(context.Background())
  138.     printEmployee(res, err)
  140.     //字段相等
  141.     q := elastic.NewQueryStringQuery("last_name:Smith")
  142.     res, err = client.Search("megacorp").Type("employee").Query(q).Do(context.Background())
  143.     if err != nil {
  144.         println(err.Error())
  145.     }
  146.     printEmployee(res, err)
  148.     //条件查询
  149.     //年龄大于30岁的
  150.     boolQ := elastic.NewBoolQuery()
  151.     boolQ.Must(elastic.NewMatchQuery("last_name", "smith"))
  152.     boolQ.Filter(elastic.NewRangeQuery("age").Gt(30))
  153.     res, err = client.Search("megacorp").Type("employee").Query(q).Do(context.Background())
  154.     printEmployee(res, err)
  156.     //短语搜索 搜索about字段中有 rock climbing
  157.     matchPhraseQuery := elastic.NewMatchPhraseQuery("about", "rock climbing")
  158.     res, err = client.Search("megacorp").Type("employee").Query(matchPhraseQuery).Do(context.Background())
  159.     printEmployee(res, err)
  161.     //分析 interests
  162.     aggs := elastic.NewTermsAggregation().Field("interests")
  163.     res, err = client.Search("megacorp").Type("employee").Aggregation("all_interests", aggs).Do(context.Background())
  164.     printEmployee(res, err)
  166. }
  168. //简单分页
  169. func list(size, page int) {
  170.     if size < 0 || page < 1 {
  171.         fmt.Printf("param error")
  172.         return
  173.     }
  174.     res, err := client.Search("megacorp").
  175.         Type("employee").
  176.         Size(size).
  177.         From((page - 1) * size).
  178.         Do(context.Background())
  179.     printEmployee(res, err)
  181. }
  183. //打印查询到的Employee
  184. func printEmployee(res *elastic.SearchResult, err error) {
  185.     if err != nil {
  186.         print(err.Error())
  187.         return
  188.     }
  189.     var typ Employee
  190.     for _, item := range res.Each(reflect.TypeOf(typ)) { //从搜索结果中取数据的方法
  191.         t := item.(Employee)
  192.         fmt.Printf("%#v\n", t)
  193.     }
  194. }
  196. func main() {
  197.     create()
  198.     delete()
  199.     update()
  200.     gets()
  201.     query()
  202.     list(1, 3)
  203. }

更多使用详见文档：https://godoc.org/github.com/olivere/elastic