# How to calculate date diffs using ingest node
**URL:** https://discuss.elastic.co/t/how-to-calculate-date-diffs-using-ingest-node/169652
**Category:** Elasticsearch
**Created:** [February 23, 2019, 7:37am UTC](https://discuss.elastic.co/t/how-to-calculate-date-diffs-using-ingest-node/169652 "2019-02-23T07:37:02Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Christian\_SANCHEZ](https://discuss.elastic.co/u/Christian_SANCHEZ)
#### Post date: [February 23, 2019, 7:37am UTC](https://discuss.elastic.co/t/how-to-calculate-date-diffs-using-ingest-node/169652/1 "2019-02-23T07:37:02Z")
Hi
I have a basic date diff between 2 dates to do and display it as weeks.
If i use the Kibana scripted fields, it works fine using the following syntax :
Math.round((doc['last\_detected'].value.toInstant().toEpochMilli() - doc['first\_detected'].value.toInstant().toEpochMilli())/((3600000\*24))/7)
However, I would like to have it calculated during the document ingestion but i can not figure which is the syntax ?
Any guess ?
---
### Author:  [@abdon](https://discuss.elastic.co/u/abdon)
#### Post date: [February 24, 2019, 1:02pm UTC](https://discuss.elastic.co/t/how-to-calculate-date-diffs-using-ingest-node/169652/2 "2019-02-24T13:02:58Z")
The `doc` syntax to access field only works at search or aggregation time. To access fields in an ingest processor, you can use the `ctx["field_name"]` syntax.
Something like the following processor should work:
```auto
{
"script": {
"source": """
if(ctx.containsKey("first_detected") && ctx.containsKey("last_detected")) {
ZonedDateTime first = ZonedDateTime.parse(ctx["first_detected"]);
ZonedDateTime last = ZonedDateTime.parse(ctx["last_detected"]);
ctx.diff = ChronoUnit.MILLIS.between(first, last);
}
"""
}
}
```
---
### Author:  [@Christian\_SANCHEZ](https://discuss.elastic.co/u/Christian_SANCHEZ)
#### Post date: [February 26, 2019, 9:49am UTC](https://discuss.elastic.co/t/how-to-calculate-date-diffs-using-ingest-node/169652/3 "2019-02-26T09:49:27Z")
Hi
Thanks a lot.
Regards
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [March 26, 2019, 9:49am UTC](https://discuss.elastic.co/t/how-to-calculate-date-diffs-using-ingest-node/169652/4 "2019-03-26T09:49:31Z")
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