MongoDB JSON array within JSON object field removal

Question

I have a json object as following:

{ "_id" : ObjectId("508806803bb97dc546e6f307"), "user_name" : "user1", "user_id" : 45645645, "likes" : [ { "event_id" : NumberLong("4578541212") },{ "event_id" : NumberLong("4578541213") } ], "dislikes" : [ ] }

I'm trying to delete specific event within likes array via java drivers tried doing this first in shell:

> db.users.update( {'likes.event_id' : 4578541212}, { '$unset':{'likes.event_id'
:1}})

with no luck...how can I manage doing that?

Do you want to remove the event_id field from the array element (leaving an empty element) or remove the element itself? — JohnnyHK
– JohnnyHK, Commented Oct 24, 2012 at 20:24

JohnnyHK · Accepted Answer · 2012-10-24 20:27:29Z

1

If you want to just remove the event_id field from the array element:

db.users.update( {'likes.event_id' : 4578541212}, {'$unset':{'likes.$.event_id' :1}})

Use the $pull operator to delete the element:

db.users.update({'likes.event_id': 4578541212}, {'$pull':{likes: {event_id: 4578541212}}})

edited Oct 24, 2012 at 20:27

answered Oct 24, 2012 at 20:14

JohnnyHK

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1 Comment

Ranco Over a year ago

thanks alot it worked, but I have another question: as I executed the command you suggested the whole record was messed up (fields switch places), any idea why is this happning?

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