Question

我使用MongoDB为应用的用户保存数据：

merge into mytable tgt
using (select 0 id, 1 loc_id, 'Lee' author from dual) src
  on (tgt.id = src.id)
when matched then
  update set tgt.loc_id = src.loc_id,
             tgt.author = src.author
when not matched then
insert (tgt.id, tgt.loc_id, tgt.author)
values (src.id, src.loc_id, src.author);

我将数据插入：

mongoose.connect(dBAddress, function(err) {
    if (err) {
        console.log('WARNING: Cannot connect to mongoDB at: ' + dBAddress);
    } else {
        dBConnected = true;
        console.log('Connected to mongoDB at: ' + dBAddress);
    }
});
var userSchema = new mongoose.Schema({
    'userName': String,
    'password': String,
    'userId': String,
    'lastModificationTime': {type: String, default: Common.getCurrentFormanttedTime()},
    'createdTime': {type: String, default: Common.getCurrentFormanttedTime()}
});
User = mongoose.model('User', userSchema);

现在我想检查那里是否有另一个var newUser = { 'userName': newUserInfo.userName, 'password': newUserInfo.password, 'userId': newUserId, 'lastModificationTime': Common.getCurrentFormanttedTime(), 'createdTime': Common.getCurrentFormanttedTime() }; var user = new User(newUser); user.save(function(err) { if (err) { console.log(err); console.log('There is a problem saving the user info'); } else { console.log('A new user saved: '); console.log(newUser); } });字段值相同的文档：

userName

现在问题是这最后一个函数永远不会返回var keyValueExists = function(key, value) { var exists = false; User.count({key: value}, function(err, count) { if (err) { console.log(err); console.log('Problem with `.find` function'); } else { console.log('count: ' + count); exists = (count !== 0); } }); return exists; };！例如，让我们假设我们在我们的集合中有这个文档：

true

（注意：这是运行mongo shell命令的结果：{ "userName": "user1" }）

当我们使用以下参数调用此函数时：db.users.find()它返回false，但是当我代替keyValueExists('userName','user1')硬编码'userName'（没有引号）时它会起作用！

为什么会这样？我怎么能摆脱这个？

Answer 1

您应该将keyValueExists功能更改为：

var keyValueExists = function(key, value, callback) {
    var exists = false;
    var query = {}; query[key] = value;

    User.count(query, function(err, count) {
        if (err) {
            console.log(err);
            console.log('Problem with `.find` function');
        } else {
            console.log('count: ' + count);
            exists = (count !== 0);
        }

        callback(err, exists);
    });
};

keyValueExists('userName','user1', function (err, isExists) {
    // your logic
});

在您的代码中，对MongoDB的请求为{key: 'user1'}而不是{userName: 'user1'}，因为对象符号字符串化

猫鼬不使用双引号？

1 个答案: