I am projecting a field as i want the difference between DateOfOcurrance and current time. Then I want to compare the diff_time field with one time which is in String format(HH:MM:SS) as I want those documents which have less than 15mins diff_time, but not getting.
{$project: {diff_time:{ $subtract: ["$DateOfOcurrance", new Date("2020-02-14")]}}},
{"$match": {"diff_time": { "$lt": "00:15:00" }}}