# 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:** 5
**Page:** 1
### Author:  [@Cyril\_SANTUNE](https://discuss.elastic.co/u/Cyril_SANTUNE)
#### Post date: [February 12, 2015, 9:31am UTC](https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128/1 "2015-02-12T09:31:12Z")
Hi,
I have a csv file as follow :
,10,CPU load,....
,3958,Memory used,....
,...,..,....
So, I parse the csv. I create a new field, I use content of the 3rd column
as name, and the 2nd column as value.
Extract of my configuration:
if [type] == "csv\_perfmon" {
csv {
columns =\> [
"syslog\_timestamp",
"value",
"name" ]
add\_field =\> {
"syslog\_severity" =\> "notice"
"syslog\_severity\_code" =\> "5"
"syslog\_hostname" =\> "10.68.63.110"
"syslog\_program" =\> "serverAgent"
"%{name}" =\> "%{value}"
}
}
date {
match =\> ["syslog\_timestamp", "UNIX\_MS"]
target =\> "syslog\_timestamp"
}
```
mutate {
rename => ["message", "syslog_message"]
convert => ["%{name}", "float"]
remove_field => [
"value",
```
"name",
"column4",
"column5"
......... ]
}
}
Everything is fine in kibana/elasticsearch, I can see the new field and its
value.
However I can not change the type of the field.
The mutate part doesn't work :
mutate {
convert =\> ["%{name}", "float"]
The field type is still a string. So I can't graph it in kibana
Note: If I don't use a variable, it works
mutate {
convert =\> ["CPU load", "float"]
Is it a bug or I miss something ?
--
You received this message because you are subscribed to the Google Groups "elasticsearch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com).
To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/61a0c0d6-8748-4266-a810-5f51ce1829d6%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/61a0c0d6-8748-4266-a810-5f51ce1829d6%40googlegroups.com).
For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout).
---
### Author:  [@GogLlundain](https://discuss.elastic.co/u/GogLlundain)
#### Post date: [March 23, 2017, 11:21am UTC](https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128/2 "2017-03-23T11:21:11Z")
I'm seeing similar today with Logstash 5.2.
@Cyril_SANTUNE did you get an anwer to this?
---
### Author:  [@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")
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).
---
### Author:  [@Cyril\_SANTUNE](https://discuss.elastic.co/u/Cyril_SANTUNE)
#### Post date: [March 23, 2017, 12:39pm UTC](https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128/4 "2017-03-23T12:39:42Z")
No, I don't have any answer. And I am not comfortable with Ruby so...
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 5, 2017, 10:01pm UTC](https://discuss.elastic.co/t/logstash-mutate-convert-doesnt-work-on-dynamic-field-name/22128/5 "2017-07-05T22:01:59Z")