# Mutate filter

**URL:** <https://discuss.elastic.co/t/mutate-filter/139156>\
**Category:** Logstash\
**Created:** [July 9, 2018, 11:42am UTC](https://discuss.elastic.co/t/mutate-filter/139156 "2018-07-09T11:42:21Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![seungtae](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/seungtae/32/71413_2.png) [@seungtae](https://discuss.elastic.co/u/seungtae)\
**Post date:** [July 9, 2018, 11:42am UTC](https://discuss.elastic.co/t/mutate-filter/139156/1 "2018-07-09T11:42:21Z")

</div>

Can I exchange the field for the existed field?

Like this..

```
mutate {
	update => {"[matchingCid][0][CID]" => [matchingCid][0][OTC2_CID]}
}

```

[matchingCid][0][CID] and [matchingCid][0][OTC2\_CID] are existed field..

---

<div class="post-metadata">

**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\
**Post date:** [July 9, 2018, 11:44am UTC](https://discuss.elastic.co/t/mutate-filter/139156/2 "2018-07-09T11:44:11Z")

</div>

```
update => {"[matchingCid][0][CID]" => "%{[matchingCid][0][OTC2_CID]}"}
```

---

<div class="post-metadata">

**Author:** ![seungtae](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/seungtae/32/71413_2.png) [@seungtae](https://discuss.elastic.co/u/seungtae)\
**Post date:** [July 9, 2018, 11:44am UTC](https://discuss.elastic.co/t/mutate-filter/139156/3 "2018-07-09T11:44:52Z")

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Thank you very much! @magnusbaeck

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<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 6, 2018, 11:45am UTC](https://discuss.elastic.co/t/mutate-filter/139156/4 "2018-08-06T11:45:02Z")

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