golang 操作 elasticsearch

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

捕获.PNG

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