# Logstash - Nested aggregation
**URL:** https://discuss.elastic.co/t/logstash-nested-aggregation/280308
**Category:** Logstash
**Created:** [August 3, 2021, 12:23pm UTC](https://discuss.elastic.co/t/logstash-nested-aggregation/280308 "2021-08-03T12:23:28Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@MattQDev](https://discuss.elastic.co/u/MattQDev)
#### Post date: [August 3, 2021, 12:23pm UTC](https://discuss.elastic.co/t/logstash-nested-aggregation/280308/1 "2021-08-03T12:23:28Z")
Hey,
I am trying to aggregate some data from a SQL DB with Logstash. The data that I am trying to import has the following structure:
- Category
-
- Type
-
-
- Product
Where each category can have multiple types, and each type can have multiple products
The data is read line by line as:
categoryid | categoryname | typeid | typename | productid | productname
The code I currently have is as follows:
```auto
filter {
aggregate {
task_id => "%{categoryid}"
code => "
map['categoryid'] = event.get('categoryid')
map['categoryname'] = event.get('categoryname')
map['types'] ||= []
map['types'] << {
'typeid' => event.get('typeid'),
'typename' => event.get('typename'),
}
map['types']['products'] ||= []
map['types']['products'] << {
'productid' => event.get('productid'),
'productname' => event.get('productname')
}
event.cancel()
"
push_previous_map_as_event => true
timeout => 3
}
}
```
Unfortunately, this code doesn't work and gives a 'String to Integer' conversion error
I've been searching for help around, but can't seem to find an answer that works.
Thanks in advance!
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [August 31, 2021, 12:23pm UTC](https://discuss.elastic.co/t/logstash-nested-aggregation/280308/2 "2021-08-31T12:23:30Z")
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