Mongoose findOneAndUpdate 只返回新的 $push 文件

Question

Here is an schema of my collection "profile":

{ 

    _id : ObjectId("2bb0fad110"), 
    name : "Tommy", 
    defaultrates : 
    [ 
            {_id : ObjectId("444cbcfd52"), rate : 35.0, raisedOn : "5/2/2009"}, 
            {_id : ObjectId("2e642b1510"), rate : 55.0, raisedOn : "5/3/2010"}, 
            {_id : ObjectId("47cc4d69d3"), rate : 65.0, raisedOn : "5/5/2010"} 
    ] 
}

I want to $push an embedded array:

{
  _id : new ObjectID(), rate : 60.0, raisedOn : "7/5/2012"
}

and return this after execution.

So I made this thru mongoose,

var condition = { '_id': "2bb0fad110"},
  insert = {
    '_id': new ObjectID(),
    'rate': 60.0,
    'raisedOn': "7/5/2012",

  },

  options = { strict: false, new: true };



function callback (err, result) {
  if (err) { console.log(err); res.status(400).send("error"); }
  console.log('result:' + JSON.stringify(result));
  res.json(result);
}


dbmodel.findOneAndUpdate(condition, { $push: { defaultrates: insert } }, options, callback);

It was good that the returned value (which is the whole object) is:

{

  _id : ObjectId("2bb0fad110"), 
  name : "Tommy", 
  defaultrates : 
  [ 
      {_id : ObjectId("444cbcfd52"), rate : 35.0, raisedOn : "5/2/2009"}, 
      {_id : ObjectId("2e642b1510"), rate : 55.0, raisedOn : "5/3/2010"}, 
      {_id : ObjectId("47cc4d69d3"), rate : 65.0, raisedOn : "5/5/2010"},
      {_id : ObjectId("65009be546"), rate : 60.0, raisedOn : "7/5/2012"}
  ] 
}

But my aim was to return only the value:

{_id : ObjectId("65009be546"), rate : 60.0, raisedOn : "7/5/2012"}

and not the whole document.

How should I do it? What did i missed in this line:

dbmodel.findOneAndUpdate(condition, { $push: { defaultrates: insert } }, options, callback);

Answer 1

Seen as you are getting the full updated object back (due to the { new: true } option), you can locate the last element in the embedded document array using JavaScript and send that as your response.

So with this object...

{
  _id : ObjectId("2bb0fad110"), 
  name : "Tommy", 
  defaultrates : 
  [ 
      {_id : ObjectId("444cbcfd52"), rate : 35.0, raisedOn : "5/2/2009"}, 
      {_id : ObjectId("2e642b1510"), rate : 55.0, raisedOn : "5/3/2010"}, 
      {_id : ObjectId("47cc4d69d3"), rate : 65.0, raisedOn : "5/5/2010"},
      {_id : ObjectId("65009be546"), rate : 60.0, raisedOn : "7/5/2012"}
  ] 
}

You can do this...

function callback (err, result) {
  if (err) { console.log(err); res.status(400).send("error"); }
  console.log('result:' + JSON.stringify(result));

  // BELOW ADDED
  const newDefaultRate = result.defaultrates[result.defaultrates.length - 1]; // gets the last element in the array
  res.status(201).json(newDefaultRate); // http status 201 to show new resource created
}

Hopefully this will help someone that comes across this thread.