Database
db={"colortag":[{"_id":ObjectId("5d3e315975132b3a43149225"),"thetime":201812,"name":"watermelon","cost":7,"info":"empty","taglist":[{"color":"red"},{"color":"green"},{"store":"market"},{"taste":"sweet"}]},{"_id":ObjectId("5d3e315975132b3a43149226"),"thetime":201812,"name":"banana","cost":7,"info":"empty","taglist":[{"store":"market"},{"taste":"sweet"}]}]}
Query
db.colortag.aggregate([{$match:{"taglist.color":{$exists:true}}}])