how to remove array filed with value null after unset in mongodb

问题

I had unset an array field, in mongo but it's leave the field with valué null,

the question is, how to remove it!

like this image http://i.stack.imgur.com/O2WiV.png

回答1:

You could remove all null elements from the array with the $pull operation.
See docs

Code example:

db.collecton.update({condition: "x"}, {$pull: {state: null}});

来源：https://stackoverflow.com/questions/19445508/how-to-remove-array-filed-with-value-null-after-unset-in-mongodb