jq filter json by dates

Question

I have some json that looks like this

 {
  \"users\":[ {  
     \"id\":8734,
     \"last_login\":\"2016-10-04T06:59:40Z\"
  },
  {  
    \"id\":9376,
    \"l         


        

Answer 1

Just add the appropriate null checks.

.users[] | select (.last_login | . == null or fromdateiso8601 > 1475625600).id 

Answer 2

One way to protect against null values of .last_login would be as follows:

.users[]
| select ( .last_login // empty | fromdateiso8601 > 1475625600)
| .id 

For clarity, though, I'd add parentheses, e.g.:

.users[]
| select ( (.last_login // empty) | fromdateiso8601 > 1475625600)
| .id 

Or more defensively still, use ?:

.users[]
| select ( .last_login | fromdateiso8601? > 1475625600)
| .id 

If you want to include items for which .last_login evaluates to null, then you could use the filter that Jeff suggested, or perhaps:

 (.last_login | fromdateiso8601? > 1475625600) // true

P.S. For "90 days before now, expressed in seconds since the beginning of the Unix epoch", you could use:

def daysAgo(days):  (now | floor) - (days * 86400);