# Blacklisting with Ruby Filter
**URL:** https://discuss.elastic.co/t/blacklisting-with-ruby-filter/282517
**Category:** Logstash
**Created:** [August 25, 2021, 7:43pm UTC](https://discuss.elastic.co/t/blacklisting-with-ruby-filter/282517 "2021-08-25T19:43:49Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@pkward](https://discuss.elastic.co/u/pkward)
#### Post date: [August 25, 2021, 7:43pm UTC](https://discuss.elastic.co/t/blacklisting-with-ruby-filter/282517/1 "2021-08-25T19:43:49Z")
Hi,
I'm looking to blacklist 1000+ nested fields. I've read in another forum that it's not possible to use the prune filter for nested filters, but I can with a ruby filter. I wanted to know is there a way to blacklist with a ruby filter using a wildcard based on the first object field? e.g., if I had a field called "File.Type.Extension", could I create a ruby filter that could blacklist all fields that begins with File or essentially File\*? Or could you provide me guidance based
"""
```auto
filter {
ruby {
code => "
def remove_fields(blacklist, event)
blacklist.each { |field| event.remove(field) }
end
blacklist = [
'[File]*'
]
remove_fields(blacklist, event)
"
}
}
```
"""
---
### Author:  [@leandrojmp](https://discuss.elastic.co/u/leandrojmp)
#### Post date: [August 25, 2021, 7:55pm UTC](https://discuss.elastic.co/t/blacklisting-with-ruby-filter/282517/2 "2021-08-25T19:55:07Z")
The example you gave can easily be done with just the `prune` filter.
It works with top-level fields, in this case the `File` json object, if you want to blacklist everything starting with `File.*`, then you can use the prune filter.
If this is not the case you will need to write a ruby code that will remove the fields according to what you do not want.
---
### Author:  [@pkward](https://discuss.elastic.co/u/pkward)
#### Post date: [August 26, 2021, 12:28am UTC](https://discuss.elastic.co/t/blacklisting-with-ruby-filter/282517/3 "2021-08-26T00:28:47Z")
Ok, I wasn't sure because I saw elsewhere that I couldn't prune nested fields. I will attempt before coming here next time.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [September 23, 2021, 12:29am UTC](https://discuss.elastic.co/t/blacklisting-with-ruby-filter/282517/4 "2021-09-23T00:29:21Z")
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