猫鼬-删除更新中的数组元素

Question

I have a JSON in this format:

{
   _id:5522ff94a1863450179abd33,
   userName:'bill',
   __v:3,
   friends:[
      {
         _id:55156119ec0b97ec217d8197,
         firstName:'John',
         lastName:'Doe',
         username:'johnDoe'
      },
      {
         _id:5515ce05207842d412c07e03,
         lastName:'Adam',
         firstName:'Foo',
         username:'adamFoo'
      }
   ]
}

And I would like to remove whole corresponding subarray. For example I want to remove user John Doe with ID 55156119ec0b97ec217d8197 so the result will be:

{
   _id:5522ff94a1863450179abd33,
   userName:'bill',
   __v:3,
   friends:[
      {
         _id:5515ce05207842d412c07e03,
         lastName:'Adam',
         firstName:'Foo',
         username:'adamFoo'
      }
   ]
}

So far I have this:

exports.delete = function (req, res) {
    var friends = req.friends[0];

    friends.update(
        {'_id': req.body.friendsId},
        {$pull: {'friends.friends': {_id: req.body.friendId}}}, function (err) {
            if (err) {
                return res.status(400).send({
                    message: getErrorMessage(err)
                });
            } else {
                res.json(friends);
            }
        });
};

But without result and also I'm not getting any error, it will stay just same as before. req.body.friendsId is ID of main array and req.body.friendId is ID of specific user which I want to pull.

Answer 1

Change your update query to this:

exports.delete = function (req, res) {
    var friends = req.friends[0]; // assuming the friends object is your mongodb collection

    friends.update(
        { '_id': req.body.friendsId },
        { $pull: {'friends': { _id: req.body.friendId } } }, function (err) {
            if (err) {
                return res.status(400).send({
                    message: getErrorMessage(err)
                });
            } else {
                res.json(friends);
            }
        });
};

This will search for documents which have the friends array element _id value = req.body.friendsId and removes the specific array element from that array using the $pull operator.