suppose have following documents in collection
{ "_id":objectid("562e7c594c12942f08fe4192"), "tags" : [ { "tagname" : "fun", "created" : isodate("2016-01-22t06:13:56.510z") }, { "tagname" : "cool", "created" : isodate("2016-01-22t06:13:56.509z") }, { "tagname" : "good", "created" : isodate("2016-01-22t06:13:56.509z") } ] }, { "_id":objectid("562e7c594c12942f08fe4193"), "tags" : [ { "tagname" : "super", "created" : isodate("2016-01-22t06:13:56.509z") }, { "tagname" : "fun", "created" : isodate("2016-01-22t06:13:56.509z") } ] }
i want search relative tags , want display tag array only.
how can query list of tag names?
to query specific field in mongodb can use find method projection parameter: https://docs.mongodb.org/manual/reference/method/db.collection.find/
db.test.find({}, {"tags.tagname":1,"_id":0}).pretty() { "tags" : [ { "tagname" : "fun" }, { "tagname" : "cool" }, { "tagname" : "good" } ] }
the first parameter blank {}
because don't have query , second parameter projection. embedded document have use dot notation "tags.tagname"
. "_id":0
not display _id
field.
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