Query specific fields of mongoDB using node.js

问题

In the code below the query gives me all the fields. I only want to query _id and serialno. How to go about it.

Schema

var DataSchema = new Schema({
  serialno: String,
  info: String,
  active: Boolean,
  content: String
});

Query

// Get list of datas
exports.index = function(req, res) {
  Data.find(function (err, data) {
    if(err) { return handleError(res, err); }
    return res.json(200, data);
  });
};

回答1:

If you are using latest nodejs mongodb driver 3.0 or above try this code:

Data.find({}).project({ _id : 1, serialno : 1 }).toArray()

回答2:

To query and return only specific fields, this is the correct request :

Data.find({}, { _id : 1, serialno : 1 }, function (err, data) {
  if(err) { return handleError(res, err); }
  return res.json(200, data);
});

The second object params is the projection params, in this object, you can set fields to return or hide.

More informations here : http://docs.mongodb.org/manual/reference/method/db.collection.find/

回答3:

In MongoDB Node.js Driver v3.1 and above:

Collection.find({}, {
   projection: {
     _id: false,
     someField: true
   }
});

Second argument to the find/findOne function is options. It supports limit, sort, projection, and many more filters.

Source: http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#findOne

回答4:

Following the documentation, you are using the function collection.find(query[[[, fields], options], callback]);

So you need to specify the fields argument:

Data.find(null, { "_id": true, "serialno": true }, function (err, data) {
    if(err) { return handleError(res, err); }
    return res.json(200, data);
  });

来源：https://stackoverflow.com/questions/28669849/query-specific-fields-of-mongodb-using-node-js

标签

node.js

mongodb

mongoose