# Painless : Use variable as regex

**URL:** <https://discuss.elastic.co/t/painless-use-variable-as-regex/99606>\
**Category:** Elasticsearch\
**Created:** [September 6, 2017, 3:02pm UTC](https://discuss.elastic.co/t/painless-use-variable-as-regex/99606 "2017-09-06T15:02:56Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![airpons1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/airpons1/32/19727_2.png) [@airpons1](https://discuss.elastic.co/u/airpons1)\
**Post date:** [September 6, 2017, 3:02pm UTC](https://discuss.elastic.co/t/painless-use-variable-as-regex/99606/1 "2017-09-06T15:02:57Z")

</div>

Hi.

I'm starting to use **painless** script in my ES queries and I'm currently struggled to convert a parameter or a variable to a Pattern.

**GET ressources/\_search**

```
{
  "query": {
    "bool": {
      "must": {
        "script": {
          "script": {
            "inline": "
              boolean find = false; 
              for( doc in params['_source']['documents']) {
                Pattern patt = /params.value/;
                if ( doc.label =~ /patt/ ) { 
                  find = true;
                } 
              } return find;",
            "lang": "painless",
            "params": {
              "value": "title"
            }
          }
        }
      }
    }
  }
}

```

So with this script my variable **patt** has value "/params.value/" instead of "/title/".  
I tried to use `def patt = ~params.value;` like suggested in Groovy doc but it's not worked too.

Anyone as a suggestion?

Thanks !

---

<div class="post-metadata">

**Author:** ![jpountz](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jpountz/32/45836_2.png) [@jpountz](https://discuss.elastic.co/u/jpountz)\
**Post date:** [September 6, 2017, 4:12pm UTC](https://discuss.elastic.co/t/painless-use-variable-as-regex/99606/2 "2017-09-06T16:12:33Z")

</div>

This is not supported: [https://www.elastic.co/guide/en/elasticsearch/painless/master/painless-syntax.html#patterns](https://www.elastic.co/guide/en/elasticsearch/painless/master/painless-syntax.html#patterns)

> Regular expression constants are directly supported. To ensure fast performance, this is the only mechanism for creating patterns. Regular expressions are always constants and compiled efficiently a single time.

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<div class="post-metadata">

**Author:** ![airpons1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/airpons1/32/19727_2.png) [@airpons1](https://discuss.elastic.co/u/airpons1)\
**Post date:** [September 6, 2017, 4:30pm UTC](https://discuss.elastic.co/t/painless-use-variable-as-regex/99606/3 "2017-09-06T16:30:17Z")

</div>

Oh I missed that.  
Thx for your answer !

---

<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:** [October 4, 2017, 4:30pm UTC](https://discuss.elastic.co/t/painless-use-variable-as-regex/99606/4 "2017-10-04T16:30:54Z")

</div>

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