Get JSON files from particular interval based on date field

I've a lot json file the structure of which looks like below:

{
  key1: 'val1'
  key2: {
          'key21': 'someval1',
          'key22': 'someval2',
          'key23': 'someval3',
          'date': '2018-07-31T01:30:30Z',
          'key25': 'someval4'
  }
  key3: []
  ... some other objects
 }

My goal is to get only these files where date field is from some period. For example from 2018-05-20 to 2018-07-20. I can't base on date of creation this files, because all of this was generated in one day. Maybe it is possible using sed or similar program?

Solution

Fortunately, the date in this format can be compared as a string. You only need something to parse the JSONs, e.g. Perl:

perl -l -0777 -MJSON::PP -ne '
   $date = decode_json($_)->{key2}{date};
   print $ARGV if $date gt "2018-07-01T00:00:00Z";
' *.json

-0777 makes perl slurp the whole files instead of reading them line by line
-l adds a newline to print
$ARGV contains the name of the currently processed file

See JSON::PP for details. If you have JSON::XS or Cpanel::JSON::XS, you can switch to them for faster processing.

I had to fix the input (replace ' by ", add commas, etc.) in order to make the parser happy.