# Logstash, converting fields

**URL:** <https://discuss.elastic.co/t/logstash-converting-fields/115075>\
**Category:** Logstash\
**Created:** [January 11, 2018, 11:48am UTC](https://discuss.elastic.co/t/logstash-converting-fields/115075 "2018-01-11T11:48:32Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![EditAxha](https://avatars.discourse-cdn.com/v4/letter/e/5f9b8f/32.png) [@EditAxha](https://discuss.elastic.co/u/EditAxha)\
**Post date:** [January 11, 2018, 11:48am UTC](https://discuss.elastic.co/t/logstash-converting-fields/115075/1 "2018-01-11T11:48:32Z")

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Hello  
i want to make some converts in my .log files, for example converting kilometer to meter.  
how can i do this?

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<div class="post-metadata">

**Author:** ![guyboertje](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/guyboertje/32/31592_2.png) [@guyboertje](https://discuss.elastic.co/u/guyboertje)\
**Post date:** [January 12, 2018, 4:43pm UTC](https://discuss.elastic.co/t/logstash-converting-fields/115075/2 "2018-01-12T16:43:50Z")

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We don't have a math filter yet. You will need to use a ruby filter.

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<div class="post-metadata">

**Author:** ![EditAxha](https://avatars.discourse-cdn.com/v4/letter/e/5f9b8f/32.png) [@EditAxha](https://discuss.elastic.co/u/EditAxha)\
**Post date:** [January 15, 2018, 9:35pm UTC](https://discuss.elastic.co/t/logstash-converting-fields/115075/3 "2018-01-15T21:35:25Z")

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Thnx, With ruby, can i make all converts that i need?

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<div class="post-metadata">

**Author:** ![guyboertje](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/guyboertje/32/31592_2.png) [@guyboertje](https://discuss.elastic.co/u/guyboertje)\
**Post date:** [January 16, 2018, 1:11pm UTC](https://discuss.elastic.co/t/logstash-converting-fields/115075/4 "2018-01-16T13:11:44Z")

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yes. This should work. Just change the `[somefield]`. If your field is called `distance` then it should be `[distance]`. If your field is a nested field then it should be `[parent][distance]` with any number of `[][][]` groups to correctly reference the field nesting.

```auto
  ruby {
    init => '
      KILOMETER_FIELD_REF = "[somefield]"
    '
    code => '
      kilometers = event.get(KILOMETER_FIELD_REF).to_f
      event.set(KILOMETER_FIELD_REF, (kilometers * 1000).round.to_i )
    '
  }

```

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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:** [February 13, 2018, 1:11pm UTC](https://discuss.elastic.co/t/logstash-converting-fields/115075/5 "2018-02-13T13:11:57Z")

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