Question

// Use connect method to connect to the server
MongoClient.connect('mongodb://localhost:27017/products', function (err, db) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  var findDocuments = function (db, callback) {
    // Get the documents collection
    var collection = db.collection('products');
    // Find some documents
    collection.find(
      { $and: [{
        "qty": {
          $gt: 0
        }
      }, {
        "price": {
          $gte: 2000.0
        }
      }]
      },
      { "name": 1,
        "brand": 1,
        "_id": 0
      }).toArray(function (err, docs) {
      assert.equal(err, null);
      console.log('Found docs');
      callback(docs);

      db.close();

    });
  }

});

function callback(docs) {
  console.log('callback called');
  console.log(docs)
}

我得到Connected successfully to server然后什么都没有，没有输出甚至是错误。我做错了什么？

Answer 1

你缺少调用函数

findDocuments(db, callback);

功能应该是这样的：

MongoClient.connect('mongodb://localhost:27017/products', function (err, db) {
assert.equal(null, err);
console.log("Connected successfully to server");

var findDocuments = function (db, callback) {
    // Get the documents collection
    var collection = db.collection('products');
    // Find some documents
    collection.find(
        {
            $and: [{
                "qty": {
                    $gt: 0
                }
            }, {
                "price": {
                    $gte: 2000.0
                }
            }]
        },
        {
            "name": 1,
            "brand": 1,
            "_id": 0
        }).toArray(function (err, docs) {
            assert.equal(err, null);
            console.log('Found docs');
            callback(docs);

            db.close();

        });
}
findDocuments(db, callback);

 });

Mongo：找不回报，也没有错误

1 个答案: