Regarding if else condition for grok filter

[Rios]

Depend how date is coming, you can set to:

• Empty string
  if ![date] {
  mutate { add_field => { "date" => "" } }
  }
• Null string
  if ![date] {
  mutate { add_field => { "date" => "Null" } }
  }
• Or null value, use ruby inside if
  How to write NULL value for a field
  Change null value from database for one field using logstash and insert into Elasticsearch - #8 by malhotras