golang操作elasticsearch的实现

1、前提

1.1 docker 安装elasticsearch

查询elasticsearch 版本

docker search elasticsearch

将对应的版本拉到本地

docker.elastic.co/elasticsearch/elasticsearch:7.3.0

创建一个网络

docker network create esnet

启动容器

docker run --name es -p 9200:9200 -p 9300:9300 --network esnet -e "discovery.type=single-node" bdaab402b220

1.2这里过后就可以去写go代码 为了直观搞了个可视化工具 elistichd 这里使用docker 部署

docker run -p 9800:9800 -d --link es:demo --network esnet -e "discovery.type=single-node" containerize/elastichd

可以试一下界面还是很美观的

2、golang 实现elasticsearch 简单的增删改查

直接上代码：

package main

import (
  "context"
  "encoding/json"
  "fmt"
  "github.com/olivere/elastic/v7"
  "reflect"
)

var client *elastic.client
var host = "http://ip:port"

type employee struct {
  firstname string  `json:"first_name"`
  lastname string  `json:"last_name"`
  age    int   `json:"age"`
  about   string  `json:"about"`
  interests []string `json:"interests"`
}

//初始化
func init() {
  //errorlog := log.new(os.stdout, "app", log.lstdflags)
  var err error
      //这个地方有个小坑 不加上elastic.setsniff(false) 会连接不上 
  client, err = elastic.newclient(elastic.setsniff(false), elastic.seturl(host))
  if err != nil {
    panic(err)
  }
  _,_,err = client.ping(host).do(context.background())
  if err != nil {
    panic(err)
  }
  //fmt.printf("elasticsearch returned with code %d and version %s\n", code, info.version.number)

  _,err = client.elasticsearchversion(host)
  if err != nil {
    panic(err)
  }
  //fmt.printf("elasticsearch version %s\n", esversion)

}

/*下面是简单的curd*/

//创建
func create() {

  //使用结构体
  e1 := employee{"jane", "smith", 32, "i like to collect rock albums", []string{"music"}}
  put1, err := client.index().
    index("megacorp").
    type("employee").
    id("1").
    bodyjson(e1).
    do(context.background())
  if err != nil {
    panic(err)
  }
  fmt.printf("indexed tweet %s to index s%s, type %s\n", put1.id, put1.index, put1.type)

  //使用字符串
  e2 := `{"first_name":"john","last_name":"smith","age":25,"about":"i love to go rock climbing","interests":["sports","music"]}`
  put2, err := client.index().
    index("megacorp").
    type("employee").
    id("2").
    bodyjson(e2).
    do(context.background())
  if err != nil {
    panic(err)
  }
  fmt.printf("indexed tweet %s to index s%s, type %s\n", put2.id, put2.index, put2.type)

  e3 := `{"first_name":"douglas","last_name":"fir","age":35,"about":"i like to build cabinets","interests":["forestry"]}`
  put3, err := client.index().
    index("megacorp").
    type("employee").
    id("3").
    bodyjson(e3).
    do(context.background())
  if err != nil {
    panic(err)
  }
  fmt.printf("indexed tweet %s to index s%s, type %s\n", put3.id, put3.index, put3.type)

}


//查找
func gets() {
  //通过id查找
  get1, err := client.get().index("megacorp").type("employee").id("2").do(context.background())
  if err != nil {
    panic(err)
  }
  if get1.found {
    fmt.printf("got document %s in version %d from index %s, type %s\n", get1.id, get1.version, get1.index, get1.type)
    var bb employee
    err:=json.unmarshal(get1.source,&bb)
    if err!=nil{
      fmt.println(err)
    }
    fmt.println(bb.firstname)
    fmt.println(string(get1.source))
  }

}
//
//删除
func delete() {

  res, err := client.delete().index("megacorp").
    type("employee").
    id("1").
    do(context.background())
  if err != nil {
    println(err.error())
    return
  }
  fmt.printf("delete result %s\n", res.result)
}
//
//修改
func update() {
  res, err := client.update().
    index("megacorp").
    type("employee").
    id("2").
    doc(map[string]interface{}{"age": 88}).
    do(context.background())
  if err != nil {
    println(err.error())
  }
  fmt.printf("update age %s\n", res.result)

}
//
////搜索
func query() {
  var res *elastic.searchresult
  var err error
  //取所有
  res, err = client.search("megacorp").type("employee").do(context.background())
  printemployee(res, err)

  //字段相等
  q := elastic.newquerystringquery("last_name:smith")
  res, err = client.search("megacorp").type("employee").query(q).do(context.background())
  if err != nil {
    println(err.error())
  }
  printemployee(res, err)



  //条件查询
  //年龄大于30岁的
  boolq := elastic.newboolquery()
  boolq.must(elastic.newmatchquery("last_name", "smith"))
  boolq.filter(elastic.newrangequery("age").gt(30))
  res, err = client.search("megacorp").type("employee").query(q).do(context.background())
  printemployee(res, err)

  //短语搜索 搜索about字段中有 rock climbing
  matchphrasequery := elastic.newmatchphrasequery("about", "rock climbing")
  res, err = client.search("megacorp").type("employee").query(matchphrasequery).do(context.background())
  printemployee(res, err)

  //分析 interests
  aggs := elastic.newtermsaggregation().field("interests")
  res, err = client.search("megacorp").type("employee").aggregation("all_interests", aggs).do(context.background())
  printemployee(res, err)

}
//
////简单分页
func list(size,page int) {
  if size < 0 || page < 1 {
    fmt.printf("param error")
    return
  }
  res,err := client.search("megacorp").
    type("employee").
    size(size).
    from((page-1)*size).
    do(context.background())
  printemployee(res, err)

}
//
//打印查询到的employee
func printemployee(res *elastic.searchresult, err error) {
  if err != nil {
    print(err.error())
    return
  }
  var typ employee
  for _, item := range res.each(reflect.typeof(typ)) { //从搜索结果中取数据的方法
    t := item.(employee)
    fmt.printf("%#v\n", t)
  }
}

func main() {
  create()
  delete()
  update()
  gets()
  query()
  list(2,1)
}

有一个小坑要注意在代码中已经注释了，如果没有添加就会有下面错误

no active connection found: no elasticsearch node available

解决

docker no elastic node aviable

关闭sniff模式；或者设置es的地址为 publish_address 地址

代码设置 sniff 为false

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