Question

由于某种原因，找不到在我的光标对象上调用的函数。这是我的代码：

var db = req.db;
var goalscollection = db.get('goalscollection');
var collection = db.get('hoursburnedcollection');

var cursor = collection.find({goal: selectedgoal}, console.log);  
// the line above prints the correct cursor object

var doc = cursor.hasNext() ? cursor.next() : null;  //line 51
// the line above gives an error

这是错误：

TypeError: undefined is not a function
at /Users/chrispark/Projects/LifeTool/node/routes/index.js:51:27
at Layer.handle [as handle_request] (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/layer.js:95:5)
at next (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/route.js:131:13)
at Route.dispatch (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/layer.js:95:5)
at /Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:277:22
at Function.process_params (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:330:12)
at next (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:271:10)
at Function.handle (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:176:3)
at router (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:46:12)

有什么我想念的吗？提前谢谢。

Answer 1

myCursor来自哪里？

使用cursor代替myCursor：

var doc = cursor.hasNext() ? cursor.next() : null;  //line 51

Answer 2

如果向find提供回调函数，则光标将仅提供给回调而不返回。因此，请删除console.log参数，然后您将获得光标。

此外，next不会返回下一个文档，它会通过异步回调提供给调用者。

var cursor = collection.find({goal: selectedgoal});
if (cursor.hasNext()) {
    cursor.next(function(err, doc) {
        console.log(doc);
    });
}

Answer 3

您确定错误行号吗？

我会说错误来自这些方面：

var goalscollection = db.get('goalscollection');
var collection = db.get('hoursburnedcollection');

我在驱动程序API中找不到任何方法get。它应该是db.collection()：

var goalscollection = db.collection('goalscollection');
var collection = db.collection('hoursburnedcollection');

TypeError：undefined不是函数 - Node.js＆amp; MongoDB的

3 个答案: