# Field value String manipulation in logstash filter

**URL:** https://discuss.elastic.co/t/field-value-string-manipulation-in-logstash-filter/97726
**Category:** Logstash
**Created:** [August 21, 2017, 8:46am UTC](https://discuss.elastic.co/t/field-value-string-manipulation-in-logstash-filter/97726 "2017-08-21T08:46:43Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![Jonesthomas](https://avatars.discourse-cdn.com/v4/letter/j/f4b2a3/32.png) [@Jonesthomas](https://discuss.elastic.co/u/Jonesthomas)
#### Post date: [August 21, 2017, 8:46am UTC](https://discuss.elastic.co/t/field-value-string-manipulation-in-logstash-filter/97726/1 "2017-08-21T08:46:43Z")

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I need to manipulate the string value of my json log, This is my sample log file  
`{"LogLevel":"ERROR","LogMsg":"{\"itemId\":0,\"module\":\"/curie/calendar/appointment\",\"action\":\"/getSlotByDate/{doctorId}/{date}\",\"errorMessage\":\"systems.ellora.core.exception.UnhandledRuntimeException: .... 108 more\\n\",\"parameter\":\"8/2017-08-31\"}","Time":"2017-08-21_02:13:31.517"}`  
1- I need to manipulate the errorMessage field value string to 50 characters.  
2-This is a valid json file.

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<div class="post-metadata">

### Author: ![Jonesthomas](https://avatars.discourse-cdn.com/v4/letter/j/f4b2a3/32.png) [@Jonesthomas](https://discuss.elastic.co/u/Jonesthomas)
#### Post date: [August 21, 2017, 8:47am UTC](https://discuss.elastic.co/t/field-value-string-manipulation-in-logstash-filter/97726/2 "2017-08-21T08:47:03Z")

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Any one?

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### Author: ![inhinyera16](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/inhinyera16/32/61625_2.png) [@inhinyera16](https://discuss.elastic.co/u/inhinyera16)
#### Post date: [August 23, 2017, 6:49pm UTC](https://discuss.elastic.co/t/field-value-string-manipulation-in-logstash-filter/97726/3 "2017-08-23T18:49:55Z")

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Not sure though, but you can try mutate convert filter to maximize string

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### Author: ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)
#### Post date: [September 20, 2017, 6:50pm UTC](https://discuss.elastic.co/t/field-value-string-manipulation-in-logstash-filter/97726/4 "2017-09-20T18:50:05Z")

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