如何删除mongodb中的json元素？

Question

Following is the content in mongodb like this:

{
"_id": 74924,
"bangs": {
    "436": {
        "join_time": 1345624851,
        "status": 1,
        "scores": 0
    },
    "446": {
        "join_time": 1355727257,
        "status": 1,
        "scores": 0
    }
},
"_id": 74926,
"bangs": {
    "436": {
        "join_time": 1345624851,
        "status": 1,
        "scores": 0
    },
    "446": {
        "join_time": 1355727257,
        "status": 1,
        "scores": 0
    }
 }
}

I want to delete :

"436": {
        "join_time": 1345624851,
        "status": 1,
        "scores": 0
    },
 where _id=74924

The result will be:

{
"_id": 74924,
"bangs": {
    "446": {
        "join_time": 1355727257,
        "status": 1,
        "scores": 0
    }
},
"_id": 74926,
"bangs": {
    "436": {
        "join_time": 1345624851,
        "status": 1,
        "scores": 0
    },
    "446": {
        "join_time": 1355727257,
        "status": 1,
        "scores": 0
    }
 }
}

I wrote the code like this:

$mongo->users->users->update(array('_id'=>74924), array('$pull'=>array('bangs'=>436)));

But the record didn't remove

How can i write the code?
Thanks in advance!

Answer 1

You can remove it with this:

db.test.update( { _id:74924 }, { $unset: {"bangs.436":1} } )

// I think this can be written in php like this:
$mongo->users->users->update(array('_id'=>74924), array('$unset'=>array('bangs.436'=>1)));