how to count number of rows of particular field of mlab database in ndoejs

i have donatedate field in schema,i am cretaed api for adding details including donate date,when i next time adding details then i need to display how many time donatedate get changed? api for adding details: router.post("/addDonate", function(req, res, next){ console.log(req.body); var newDonaterecord = new Donaterecord(req.body); console.log(newDonaterecord); newDonaterecord.save(function (err, doc) { if (err){ return res.json(err);} else{ return res.status(200);} console.log('Saved Doc'+ doc); }); res.json('Donation Details Added Successfully!!!'); });

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