Remove null element from mongo array

Question

{
        "_id" : 160,
        "info" : [
            {
                'name': 'Serg',
                'proff': 'hacker'
            },
            null,
        ]
    }

As you can see I have null element in my array, I need a general solution that will remove null elements from info array.

I tried this:

for doc in iter:
    people.update({ '_id' : doc['_id']}, { '$pull' : { 'info' : 'null' }})

where iter is a collection of documents. and people is a collection

I also tried this in the shell:

> db.people.findAndModify({ query: {}, update: {'$pull': {info:null} } } )

But none of the above examples delete this null from my documents!! ))

score 22 · Accepted Answer · edited May 23 '17 at 12:10

This should work out for you. In python null is called None.

    for doc in iter:
        people.update({'_id':doc[id]},{'$pull':{'info':None}})

null object in Python?

Also in mongo shell, this should work out:

    db.people.update({_id:160},{$pull:{info:null}})

If you want the update operator, to update more that one document at a time, that is to pull out null values from multiple documents, then you have to supply the multi:true option. Because by default, if the query arguemnt is left blank i.e. {} and mulit:true is not provided, update operator works on the first document that it finds

    db.people.update({},{$pull:{info:null}},{multi:true})

Remove null element from mongo array

1 Answers1