node.js - Mongoose 查询 : how to pass a variable

Question

如何在下面的 Xcom.find({ $where : "this.NIC_No == '5'"} 中传递 'n' 而不是硬编码的 '5'？

exports.query_by_nic = function ( req, res ){
  var n = req.body.NIC_No;
  console.log(n); //n prints correctly as expected
  Xcom.find({ $where : "this.NIC_No == '5'" }, function ( err, xcoms ){ //works with '5' but how do I query for 'n'?
     res.render( 'query_by_nic', {
        title   : 'Query by NIC',
        xcoms   : xcoms
    });
    console.log(err);
    console.log(xcoms);
  });
};

Answer 1

你可以这样做:

Xcom.find({ $where : "this.NIC_No == '" + variableThatContainsNumber + "'" }, function ( err, xcoms ){
    ...
});

或者更好:

Xcom.find({NIC_No: variableThatContainsNumber}, function(err, doc) {
    ...
});

第二个要好得多，因为它不需要在 MongoDB 中执行 JavaScript。