How to send NULL DATE value to elasticsearch using logstash

Its a blocker to me.
I am not able to send NULL DATE value to the elasticsearch using logstash.
null value storing as string in elasticsearch.
if actual comes with proper date like 2012-01-01 11:11:11 it is also string as string even after converting to date using with the date filter.

Thanks in advance.

Are you using timebased indices?

monthly indices,weekly indices

Then what is the value in sending a null timestamp? It'll just get put into the wrong index.

I have one date field called datetime.
it can have null values(null) and date values(2011-01-01 11:11:11.111).
I am converting this date field to date using date filter like below

if[datetime]!='null' and [datetime]!='NULL'{
date {
match => [ "datetime", "YYYY-MM-dd HH:mm:ss.SSS" ]
target =>"datetime"
if it is null logstash storing as null string like 'null'.
it should be store as null only.

Except that will break in ES because it is not a valid timestamp.
I don't think there is a good solution to your problem here.

null date valid only .
In RDBMS we can store null date also.why cant in ES

Elasticsearch allows to store null dates using api
if we check mapping ANSWEREDON data type is date only.
But from logstash not able to store null date.