UnhandledPromiseRejectionWarning：.aggregate()不是函数

Question

我试图用这个管道执行.aggregate()函数，但是我得到了以下错误：

UnhandledPromiseRejectionWarning: TypeError: User.find(...).select(...).sort(...).aggregate is not a function

const users = await User
            .find(findParams)
            .select(userResponse)
            .sort(sortParams)
            .aggregate([
                {$group: {_id: "$_id", dateCreated: {$first: "$dateCreated"}}},
                {$set: {dateCreated: {$dateToString: {format: "%d.%m.%G %H:%M:%S", date: "$dateCreated"}}}}
            ])
            .exec()

用户是我从MongoDB收集的。是否需要更多管道来拒绝此错误？谢谢

Answer 1

.find()返回一个不能调用.aggregate()的游标。您需要将聚合管道直接传递给.aggregate()。

const users = await User.aggregate([
                {$group: {_id: "$_id", dateCreated: {$first: "$dateCreated"}}},
                {$set: {dateCreated: {$dateToString: {format: "%d.%m.%G %H:%M:%S", date: "$dateCreated"}}}}
            ])
            .exec()

Answer 2

你好，我的朋友聚合()方法仅用于模式，如下所示

const users = await User
        .aggregate([
            {$group: {_id: "$_id", dateCreated: {$first: "$dateCreated"}}},
            {$set: {dateCreated: {$dateToString: {format: "%d.%m.%G %H:%M:%S", date: "$dateCreated"}}}}
        ])
        .exec()

跟踪这个文档，您将得到更好的聚合()方法的概念。