Question

我使用express.js和mongoose进行mongoDB访问。如果有人输入不存在的URL（基于user_id），我会尝试实现回退。这是代码：

app.get('/track/:id', function(req, res) {
var user_id = req.params.id;
User.findById(user_id, function(err, user_) {
    if (!err) {
        res.render('track', { pins: user_.pins, layout: false });
    } else {
        res.send("FAIL! " + err);
    }
});
});

当访问http://foo.bar/track/1234并且1234不存在时，它应该打印出FAIL !,如果id存在，它应该从db获取它的内容（这实际上有效）。输入错误的ID（应用程序崩溃）时，这就是我现在得到的结果：

/home/node/node-service/releases/20110530081158/server.js:112
            res.render('track', { pins: user_.pins, layout: false });
                                             ^
TypeError: Cannot read property 'pins' of null
    at /home/node/node-service/releases/20110530081158/server.js:112:46
    at /home/node/.node_libraries/.npm/mongoose/1.3.6/package/lib/mongoose/query.js:778:22
    at [object Object].<anonymous> (/home/node/.node_libraries/.npm/mongoose/1.3.6/package/support/node-mongodb-native/lib/mongodb/collection.js:462:35)
    at [object Object].emit (events.js:67:17)
    at [object Object].<anonymous> (/home/node/.node_libraries/.npm/mongoose/1.3.6/package/support/node-mongodb-native/lib/mongodb/db.js:94:12)
    at [object Object].emit (events.js:64:17)
    at Socket.<anonymous> (/home/node/.node_libraries/.npm/mongoose/1.3.6/package/support/node-mongodb-native/lib/mongodb/connection.js:86:16)
    at Socket.emit (events.js:64:17)
    at Socket._onReadable (net.js:671:31)
    at IOWatcher.onReadable [as callback] (net.js:177:10)

Answer 1

不返回不存在的ID的数据是正常操作，而不是错误，因此没有设置错误。

尝试将if (!err)更改为if (!err && user_)。

Answer 2

尝试切换回调参数＆gt;

User.findById(user_id, function(user_, err ) {
    if (!err) {
        res.render('track', { pins: user_.pins, layout: false });
    } else {
        res.send("FAIL! " + err);
    }
});

express.js + mongoose：回拨错误的ID？

2 个答案: