# Manipulating Nested Fields

**URL:** <https://discuss.elastic.co/t/manipulating-nested-fields/320768>\
**Category:** Logstash\
**Created:** [December 8, 2022, 10:33am UTC](https://discuss.elastic.co/t/manipulating-nested-fields/320768 "2022-12-08T10:33:20Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![dawiro](https://avatars.discourse-cdn.com/v4/letter/d/71e660/32.png) [@dawiro](https://discuss.elastic.co/u/dawiro)\
**Post date:** [December 8, 2022, 10:33am UTC](https://discuss.elastic.co/t/manipulating-nested-fields/320768/1 "2022-12-08T10:33:20Z")

</div>

Hi,  
Given a field `[field][sub-field]`, how can I move the value from "sub-field" to field? That is, convert this from an object to a string?

I've tried:

```auto
mutate {
    covert => { "field" => "string" }
}

```

and:

```auto
 mutate {
    copy => { [field][subfield] => "new_field" }
}

```

Neither has worked.

Thx  
D

---

<div class="post-metadata">

**Author:** ![Rios](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rios/32/95745_2.png) [@Rios](https://discuss.elastic.co/u/Rios)\
**Post date:** [December 8, 2022, 10:44am UTC](https://discuss.elastic.co/t/manipulating-nested-fields/320768/2 "2022-12-08T10:44:45Z")

</div>

If you want convert:

```auto
mutate {
    covert => { "[field][sub-field]" => "string" }
}

```

Copy:

```auto
 mutate {
    copy => { "[field][subfield]" => "new_field" }
}

```

---

<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:** [January 5, 2023, 10:44am UTC](https://discuss.elastic.co/t/manipulating-nested-fields/320768/3 "2023-01-05T10:44:52Z")

</div>

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