# Using input field for pattern matching
**URL:** https://discuss.elastic.co/t/using-input-field-for-pattern-matching/40651
**Category:** Logstash
**Created:** [February 1, 2016, 4:14pm UTC](https://discuss.elastic.co/t/using-input-field-for-pattern-matching/40651 "2016-02-01T16:14:53Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Dheeraj](https://discuss.elastic.co/u/Dheeraj)
#### Post date: [February 1, 2016, 4:14pm UTC](https://discuss.elastic.co/t/using-input-field-for-pattern-matching/40651/1 "2016-02-01T16:14:53Z")
Hi,
Is it possible to use an input field to match the pattern via multiline/grok filter. For example, following doesn't work :
```
multiline {
pattern => [log_pattern]
negate => true
what => "previous"
source => "data"
}
```
Use case:
I am trying to setup a logstash multiline parser with inputs from different applications. I'd like to make the applications set a pattern field which will be used for matching.
---
### Author:  [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)
#### Post date: [February 1, 2016, 5:34pm UTC](https://discuss.elastic.co/t/using-input-field-for-pattern-matching/40651/2 "2016-02-01T17:34:20Z")
Theoretically,
```auto
multiline {
pattern => "%{log_pattern}"
...
}
```
could be made to work for a multiline filter, but then every single event would need to have a `log_pattern` field. Except for a few plugins (like multiline), Logstash doesn't keep any state between events.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 5:13am UTC](https://discuss.elastic.co/t/using-input-field-for-pattern-matching/40651/3 "2017-07-06T05:13:31Z")