# Extracting Substrings Using Runtime Fileds

**URL:** <https://discuss.elastic.co/t/extracting-substrings-using-runtime-fileds/317547>\
**Category:** Kibana\
**Tags:** runtime-fields\
**Created:** [October 26, 2022, 3:28pm UTC](https://discuss.elastic.co/t/extracting-substrings-using-runtime-fileds/317547 "2022-10-26T15:28:04Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![hi\_xavier](https://avatars.discourse-cdn.com/v4/letter/h/ac91a4/32.png) [@hi\_xavier](https://discuss.elastic.co/u/hi_xavier)\
**Post date:** [October 26, 2022, 3:28pm UTC](https://discuss.elastic.co/t/extracting-substrings-using-runtime-fileds/317547/1 "2022-10-26T15:28:04Z")

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Hello,

With runtime fields, is it possible to extract a substring from a given field? For example,

> "url" : "[https://hello.com/random?username](https://hello.com/random?username)"

How would I create a runtime field to grab the "username" string ?

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<div class="post-metadata">

**Author:** ![Marco\_Liberati](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/marco_liberati/32/82953_2.png) [@Marco\_Liberati](https://discuss.elastic.co/u/Marco_Liberati)\
**Post date:** [October 27, 2022, 8:51am UTC](https://discuss.elastic.co/t/extracting-substrings-using-runtime-fileds/317547/2 "2022-10-27T08:51:44Z")

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Hi @hi_xavier

For the time being some string manipulation will do it, but there's [a proposal to add a URL parser](https://github.com/elastic/elasticsearch/issues/60660) to Painless which will make it safer:

```auto
emit(url.substring(url.indexOf('?') + 1));

```

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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 23, 2022, 11:44pm UTC](https://discuss.elastic.co/t/extracting-substrings-using-runtime-fileds/317547/3 "2022-11-23T23:44:32Z")

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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:** [December 21, 2022, 8:41pm UTC](https://discuss.elastic.co/t/extracting-substrings-using-runtime-fileds/317547/4 "2022-12-21T20:41:09Z")

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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:** [January 18, 2023, 8:41pm UTC](https://discuss.elastic.co/t/extracting-substrings-using-runtime-fileds/317547/5 "2023-01-18T20:41:39Z")

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