我有这样的数据：

[
  {
    "_id": "60ccb13a21d65f0c7c4c0690",
    "username": "testuser",
    "friendRequests": [
      {
        "_id": "60ccb13a21d65f0c7c4c0690",

      }
    ]
  }
]

代码如下：

router.use(async function(req, res, next){

    try {
        res.locals.fr = await User.aggregate([
            {$match:{username: "testuser"}},    
            {$project: {
                frCount: {
                  $size: "$friendRequests"
                }
              }}]),
        res.locals.login = req.isAuthenticated();
        res.locals.newProfile = req.user;
        next();
    }
    catch {
        res.locals.login = req.isAuthenticated();
        res.locals.newProfile = req.user;
        next();
    }

});

它不应该还这个吗？

[
  {
    "frCount": 1,
    "_id": ObjectId("60ccb13a21d65f0c7c4c0690")
  }
]

那么如果我把它放在ejs中：

<p>requests: <%= fr.frCount %></p>

它不应该返回1吗？然而，它什么也不返回，我不知道为什么。