通过字符串初始化documentReference失败

我有一个方法,它返回一个字符串,我确信该字符串指向文档。按以下方式使用该字符串时:

const docRef = "users/uid/data/online"
const dbPath = db.doc(docRef)
console.log(dbPath.path)
return dbPath.set({"test" : 1})

它失败:

如果我使用db。集合(“用户”)。文档(uid)。。。。。。它起作用了。如何通过typescript中的字符串创建文档引用?

应根据以下文件进行操作: https://firebase.google.com/docs/firestore/data-model#references

编辑:这是我的班级:

export enum UserCollection {
    online = "online",
    private = "private",
    server = "server"
}

export enum UserDocument { 
    online = "online",
    private = "private",
    server = "server"
}

class ManagerPath { 

    pathToUser = "users/"

    getPathToUser(uid: string, userCollection: UserCollection, userDocument: UserDocument): string { 
        return this.pathToUser + "/" + uid + "/" + userCollection + "/" + userDocument;
    }

}

export const managerPath = new ManagerPath();

这就是我检索路径的方式:

exports.initializeNewUser = functions.auth.user().onCreate((user) => {
    const test = managerPath.getPathToUser(user.uid, UserCollection.online, UserDocument.online);
    console.log(test)
    const dbPath = db.doc(test)
    return dbPath.set({"dateCreation" : Date.now()}) //fails
})