Menu
{
"_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!! ))
742
You could remove all null elements from the array with the $pull operation. In the $pull condition you have to set the value that should be removed from the array not the index. So in you're case {$pull:{province:null}} . NOTE: This removes ALL null values from the array.
To remove an element, update, and use $pull in MongoDB. The $pull operator removes from an existing array all instances of a value or values that match a specified condition.
Solution 1: In case preservation of all null values[] or null fields in the array itself is not necessary. Filter out the not null elements using $filter , the ( all null elements) array would be empty, filter that out from documents using $match then $sort on values .
The $pop operator removes the first or last element of an array. Pass $pop a value of -1 to remove the first element of an array and 1 to remove the last element in an array.
This should work out for you. In python null is called None.
for doc in iter:
people.update({'_id':doc[id]},{'$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})
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
