# Performing a function if a value is inside an array

**URL:** https://discuss.elastic.co/t/performing-a-function-if-a-value-is-inside-an-array/201826
**Category:** Logstash
**Created:** [October 1, 2019, 2:38pm UTC](https://discuss.elastic.co/t/performing-a-function-if-a-value-is-inside-an-array/201826 "2019-10-01T14:38:44Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Jasonespo](https://avatars.discourse-cdn.com/v4/letter/j/898d66/32.png) [@Jasonespo](https://discuss.elastic.co/u/Jasonespo)
#### Post date: [October 1, 2019, 2:38pm UTC](https://discuss.elastic.co/t/performing-a-function-if-a-value-is-inside-an-array/201826/1 "2019-10-01T14:38:45Z")

</div>

This is my array:

"device\_tag": [  
"DeviceA",  
"DeviceB"  
]

Essentially I want to do something if tag is Device A and something else if Device is tag B.

```
if [device_tag] == "DeviceA" {
mutate { do something here } }

if [device_tag] == "DeviceB" {
mutate { do something else here } }

```

But this doesn't seem to work, any ideas?

Also tried

```
if [device_tag] =~ /DeviceA/ {
mutate { do something here }
```

---

<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: [October 1, 2019, 5:03pm UTC](https://discuss.elastic.co/t/performing-a-function-if-a-value-is-inside-an-array/201826/2 "2019-10-01T17:03:56Z")

</div>

You can test array membership using in

```
if "DeviceA" in [device_tag] {
```

---

<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: [October 29, 2019, 5:03pm UTC](https://discuss.elastic.co/t/performing-a-function-if-a-value-is-inside-an-array/201826/3 "2019-10-29T17:03:58Z")

</div>

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