# How to iterate through json array and print a formatted string?
**URL:** https://discuss.elastic.co/t/how-to-iterate-through-json-array-and-print-a-formatted-string/319676
**Category:** Logstash
**Created:** [November 23, 2022, 5:39pm UTC](https://discuss.elastic.co/t/how-to-iterate-through-json-array-and-print-a-formatted-string/319676 "2022-11-23T17:39:07Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@learningelastic](https://discuss.elastic.co/u/learningelastic)
#### Post date: [November 23, 2022, 5:39pm UTC](https://discuss.elastic.co/t/how-to-iterate-through-json-array-and-print-a-formatted-string/319676/1 "2022-11-23T17:39:07Z")
I'm learning how to use logstash and I got things to mostly work. But I want to learn how to iterate through a json array and print a formatted result set. For example, I created a file called `/root/test.log` with the following content:
```auto
{"message":"Server log: Log title: 'Search Results';- Hits: {\"title\":\"Book 1\",\"author\":\"Jim\"},{\"title\":\"Book 2\",\"author\":\"Jen\"};---"}
{"message":"Server log: Log title: 'Search Results';- Hits: {\"title\":\"Book 3\",\"author\":\"Jess\"},{\"title\":\"Book 4\",\"author\":\"Jazz\"},{\"title\":\"Book 5\",\"author\":\"Jules\"};---"}
```
Then from my bash, I ran this command:
```auto
/usr/share/logstash/bin/logstash -e 'input {
file {
type => "json"
codec => "json"
path => "/root/test.log"
start_position => beginning
}
}
filter {
grok {
match => {
"message" => "Server log: Log title: '%{DATA:logtitle}';- Hits: %{DATA:hitlist};---"
}
}
mutate {
add_field => { "hitstring" => "[%{hitlist}]" }
remove_field => ["hitlist"]
}
json {
source => "hitstring"
target => "hits"
}
mutate {
remove_field => ["hitstring"]
}
}
output {
email {
to => "user@example.com"
from => "user@example.com"
subject => "Alert: %{logtitle}"
body => "Here are your results\nBook1\nTitle: %{[hits][0][title]}\nAuthor: %{[hits][0][author]}\n\n\nBook2\nTitle: %{[hits][1][title]}\nAuthor: %{[hits][1][author]}\n\n"
authentication => "plain"
address => "smtp.mailtrap.io"
domain => "smtp.mailtrap.io"
port =>2525
username => "my-username"
password => "my-password"
}
stdout {
codec => line {
format => "Here are your results\nBook1\nTitle: %{[hits][0][title]}\nAuthor: %{[hits][0][author]}\n\n\nBook2\nTitle: %{[hits][1][title]}\nAuthor: %{[hits][1][author]}\n\n"
}
}
}'
```
This works except the second result is missing the `Book3 Title: Book 5 Author: Jules`. I could fix this by adding a `Book3\nTitle: %{[hits][2][title]}\nAuthor: %{[hits][2][author]}`. But is there a way to iterate through the json array and print out a string dynamically instead of hardcoding my string?
---
### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [November 23, 2022, 6:27pm UTC](https://discuss.elastic.co/t/how-to-iterate-through-json-array-and-print-a-formatted-string/319676/2 "2022-11-23T18:27:47Z")
> [@learningelastic](#):
>
> is there a way to iterate through the json array and print out a string dynamically
You would have to use ruby, something like
```
json { source => "hitstring" target => "hits" }
ruby {
code => '
h = event.get("hits")
if h.is_a? Array
s = ""
h.each_index { |x|
title = h[x]["title"]
author = h[x]["author"]
s += "Book#{x+1}\nTitle: #{title}\nAuthor: #{author}\n"
}
event.set("[@metadata][list]", s)
end
'
}
```
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [December 21, 2022, 6:28pm UTC](https://discuss.elastic.co/t/how-to-iterate-through-json-array-and-print-a-formatted-string/319676/3 "2022-12-21T18:28:43Z")
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