# How to append a string to a value?

**URL:** <https://discuss.elastic.co/t/how-to-append-a-string-to-a-value/298542>\
**Category:** Logstash\
**Created:** [March 1, 2022, 5:14pm UTC](https://discuss.elastic.co/t/how-to-append-a-string-to-a-value/298542 "2022-03-01T17:14:25Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![mohsin106](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mohsin106/32/65203_2.png) [@mohsin106](https://discuss.elastic.co/u/mohsin106)\
**Post date:** [March 1, 2022, 5:14pm UTC](https://discuss.elastic.co/t/how-to-append-a-string-to-a-value/298542/1 "2022-03-01T17:14:25Z")

</div>

Hi,

I would like to append the letter C to this key:  
`"module-temp": 32.37` so that it looks like` "module-temp": 32.37 C`

Tried this but didn't work:

```auto
 if ("*" in [module-temp]) {
        mutate {
            replace => {"module-temp" => "%{module-temp} C"}
        }
    }

```

---

<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:** [March 1, 2022, 5:28pm UTC](https://discuss.elastic.co/t/how-to-append-a-string-to-a-value/298542/2 "2022-03-01T17:28:09Z")

</div>

> [@mohsin106](#):
>
> `if ("*" in [module-temp]) {`

What are you trying to test using that conditional? The mutate+replace looks good.

---

<div class="post-metadata">

**Author:** ![mohsin106](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mohsin106/32/65203_2.png) [@mohsin106](https://discuss.elastic.co/u/mohsin106)\
**Post date:** [March 1, 2022, 7:48pm UTC](https://discuss.elastic.co/t/how-to-append-a-string-to-a-value/298542/3 "2022-03-01T19:48:55Z")

</div>

> [@Badger](#):
>
> What are you trying to test using that conditional? The mutate+replace looks good.

I was just trying an alternate to:

```auto
 if [module-temp] {
        mutate {
            replace => {"module-temp" => "%{module-temp} C"}
        }
    }

```

---

<div class="post-metadata">

**Author:** ![aaron-nimocks](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/aaron-nimocks/32/73965_2.png) [@aaron-nimocks](https://discuss.elastic.co/u/aaron-nimocks)\
**Post date:** [March 1, 2022, 7:53pm UTC](https://discuss.elastic.co/t/how-to-append-a-string-to-a-value/298542/4 "2022-03-01T19:53:57Z")

</div>

What you have here works if you use your second conditional statement method.

**Conf**

```auto
input {
  generator {
    message => '{"module-temp": 32.37} '
    count => 1
    codec => "json"
  }
}
filter {
  if [module-temp] {
    mutate {
      replace => {"module-temp" => "%{module-temp} C"}
    }
  }  
}
output {
  stdout { }
}

```

**Output**

```auto
"module-temp": "32.37 C"

```

---

<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:** [March 29, 2022, 7:54pm UTC](https://discuss.elastic.co/t/how-to-append-a-string-to-a-value/298542/5 "2022-03-29T19:54:17Z")

</div>

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