MongoDB insert field to existing document if does not already exist

Question

I have a document like this (this is very simplified):

{
    'name' : 'test',
    'age' : 16
}

and also this

{
    'name' : 'test2'
}

I want to set all 'age' to 14 if it does not exist.

How can I do this?

Answer 1

尝试$exists 运算符 ：

$this->mongolib->update('people', array('age' => array('$exists' => false)), array('$set' => array('age' => 14)), array('upsert' => true, 'multiple' => true));

Answer 2

I have a roundabout way that I can think of. I suggest you use the normal update command but just add a regex condition in your selection criteria to match only those documents that do not have a value (or numeric value) set for the 'age' attribute.