# Logstash: mutate convert doesn't work on dynamic field name

**URL:** https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128
**Category:** Elasticsearch
**Created:** [February 12, 2015, 9:31am UTC](https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128 "2015-02-12T09:31:12Z")
**Posts on this page:** 1
**Showing post:** 3

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### Author: ![GogLlundain](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/gogllundain/32/15620_2.png) [@GogLlundain](https://discuss.elastic.co/u/GogLlundain)
#### Post date: [March 23, 2017, 11:34am UTC](https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128/3 "2017-03-23T11:34:22Z")

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Answering my own question here.  
I found [this thread](https://discuss.elastic.co/t/solved-the-filter-plugin-mutate-convert-doesnt-work-in-5-0/65496/15) with the same issue. This is a known limitation and the answer is to use a bit of ruby to convert fields that have dynamic field names.

I'm going to try and find an example bit of ruby and post it back here.  
And possibly [here too](https://github.com/logstash-plugins/logstash-filter-mutate/issues/57).

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_[View the full topic](https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128)._