# Logstash dynamic fields
**URL:** https://discuss.elastic.co/t/logstash-dynamic-fields/201487
**Category:** Logstash
**Created:** [September 28, 2019, 10:13am UTC](https://discuss.elastic.co/t/logstash-dynamic-fields/201487 "2019-09-28T10:13:40Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Ankit\_Sawant](https://discuss.elastic.co/u/Ankit_Sawant)
#### Post date: [September 28, 2019, 10:13am UTC](https://discuss.elastic.co/t/logstash-dynamic-fields/201487/1 "2019-09-28T10:13:40Z")
I have a field "msg\_string" in my logs which has multiple fields saparated by tilda "~"
e.g. msg\_string =firstname~lasname~city~hobby~marks ...
position of fields firstname,lastname are at index 0 and 1
the position of field city is not fixed i can appear anywhere in msg\_string hence i am using look up with city names. I am using split to saparate out fields in msg\_string and extract firstname and lastname
I have a file with city names for look up i want to add a field name city using lookup file
how to do it please help.
split =\> ["msg\_string","~"]
add\_field =\> {"firstname"=\> "%{[msg\_string][0]}"}
add\_field =\> {"lastname"=\> "%{[msg\_string][1]}"}
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### Author:  [@amanpradhan](https://discuss.elastic.co/u/amanpradhan)
#### Post date: [September 30, 2019, 7:10am UTC](https://discuss.elastic.co/t/logstash-dynamic-fields/201487/2 "2019-09-30T07:10:03Z")
i am facing the similar problem please reply asap as it is very important for me!!
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### Author:  [@ylasri](https://discuss.elastic.co/u/ylasri)
#### Post date: [September 30, 2019, 7:16am UTC](https://discuss.elastic.co/t/logstash-dynamic-fields/201487/3 "2019-09-30T07:16:38Z")
You can use [translate](https://www.elastic.co/guide/en/logstash/current/plugins-filters-translate.html) filter
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### Author:  [@Ankit\_Sawant](https://discuss.elastic.co/u/Ankit_Sawant)
#### Post date: [September 30, 2019, 3:53pm UTC](https://discuss.elastic.co/t/logstash-dynamic-fields/201487/4 "2019-09-30T15:53:53Z")
Can I use translate filter inside ruby filter ?? As I have to iterate over msg\_string which can be done in ruby filter
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [October 28, 2019, 3:54pm UTC](https://discuss.elastic.co/t/logstash-dynamic-fields/201487/5 "2019-10-28T15:54:13Z")
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