# Decode\_json on partial field

**URL:** <https://discuss.elastic.co/t/decode-json-on-partial-field/203904>\
**Category:** Beats\
**Tags:** filebeat\
**Created:** [October 16, 2019, 5:56pm UTC](https://discuss.elastic.co/t/decode-json-on-partial-field/203904 "2019-10-16T17:56:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dnorth98](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dnorth98/32/54823_2.png) [@dnorth98](https://discuss.elastic.co/u/dnorth98)\
**Post date:** [October 16, 2019, 5:56pm UTC](https://discuss.elastic.co/t/decode-json-on-partial-field/203904/1 "2019-10-16T17:56:54Z")

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Hi there,  
I'm pulling in a log with filebeat with lines that look like this:

`I, [2019-10-16T17:44:37.242758 #17339] INFO -- : [ac4878f8-b88b-406f-8271-f7efb873e200] {"method":"GET","path":"/healthcheck","format":"text","controller":"HealthCheck::HealthCheckController","action":"index","status":200,"duration":4.71,"view":0.14,"db":2.25,"params":{"action":"index"},"plan_name":null,"admin_id":null,"admin_name":null}`

So there's some preamble prefixing a json object. What I'd like to do is use decode\_json only on the json part of this field (in this case, the whole text comes in just in the`message` field. Is there some way to break this up and run the json decode only on the json part?

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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:** [November 13, 2019, 5:57pm UTC](https://discuss.elastic.co/t/decode-json-on-partial-field/203904/2 "2019-11-13T17:57:02Z")

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