Very unusual mongoose behavior: find () returns only one document

Question

Very unusual mongoose behavior: find () returns only one document

I have been working with mongoose for a while, and I'm currently stuck with this problem:

I have a dynamic MongoDB database on which express-end batch inserts records using Model.collection.insert. The insert is perfect, I see all the documents on demand using the mongo shell, and the number of documents is as expected.

Here is the format of the inserted documents:

[  
   {  
      "disk":"Aff90",
      "graph":
       {
         "Q1":{  
            "frequency":21
         },
         "Q2":{  
            "frequency":13
         },
         "Q3":{  
            "frequency":35
         },
         "Q4":{  
            "frequency":24
         }
      },
      "sales": 987,
      "deep_discount": 50,
      "demand_score": 3.4
   },
   {  
      "disk":"B721",
      "graph":
       {
         "Q1":{  
            "frequency":98
         },
         "Q2":{  
            "frequency":129
         },
         "Q3":{  
            "frequency":812
         },
         "Q4":{  
            "frequency":240
         }
      },
      "sales": 2017,
      "deep_discount": 80,
      "demand_score": 7.4
   },//and so on(about 1000 documents) 
]

However, when I use my express point to request this data, it returns only the first element. I have not encountered this specific problem with mongoose yet and could not find a solution on the Internet.

Express API to retrieve:

router.post('/end-point',  function(req, res, next) {

  model.find({}, {"_id":0}, function(err, data){
      if(err){
        throw err;
      }
      if(data.length){
        res.json(data);
      }
   });
});