# Concatenate two fields

**URL:** https://discuss.elastic.co/t/concatenate-two-fields/241817
**Category:** Logstash
**Created:** [July 19, 2020, 10:04pm UTC](https://discuss.elastic.co/t/concatenate-two-fields/241817 "2020-07-19T22:04:54Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Jasmin](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jasmin/32/56586_2.png) [@Jasmin](https://discuss.elastic.co/u/Jasmin)
#### Post date: [July 19, 2020, 10:04pm UTC](https://discuss.elastic.co/t/concatenate-two-fields/241817/1 "2020-07-19T22:04:55Z")

</div>

hi ,  
i am using mutate add\_field to concatenate two fileds to make them a unique id ,  
but ouptut give me this :  
{  
"\_index" : "sql",  
"\_type" : "\_doc",  
"\_id" : " %{GL\_ETABLISSEMENT} %{GL\_NUMERO} ",  
"\_score" : 1.0,  
"\_source" : {  
"gp\_numero" : 205029243,  
"gl\_qtefact" : 1.0,  
"gl\_datepiece" : "2019-05-11T23:00:00.000Z",  
"gl\_etablissement" : "205",  
"gl\_article" : "28ZFPNG01 00502N X",  
"gl\_totalttc" : 41.757,  
"gl\_representant" : "101810",  
"gp\_dtsvlastchange" : "2019-05-12T14:17:41.147Z",  
"gp\_dtsvcreate" : "2019-05-12T14:17:41.147Z",  
"gl\_puttcbase" : 44.9,  
"gl\_codearticle" : "28ZFPNG01",  
"@timestamp" : "2020-07-19T21:33:51.173Z",  
"@version" : "1",  
"newfield" : " %{GL\_ETABLISSEMENT} %{GL\_NUMERO}"  
}

I CANNOT concatenate .

---

<div class="post-metadata">

### Author: ![Badger](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/badger/32/25190_2.png) [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [July 19, 2020, 10:39pm UTC](https://discuss.elastic.co/t/concatenate-two-fields/241817/2 "2020-07-19T22:39:00Z")

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Field name are case sensitive. Try

```
mutate { add_field => { "newfield" => "%{gl_etablissement}" %{gp_numero" } }

```

It's gp\_numero, not gl\_numero, right?

---

<div class="post-metadata">

### Author: ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)
#### Post date: [August 16, 2020, 10:39pm UTC](https://discuss.elastic.co/t/concatenate-two-fields/241817/3 "2020-08-16T22:39:08Z")

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