为什么mongodb文件不更新？

Question

我有一个获取request.user属性并更新其值的函数，如下面的代码所示。问题在于更新后的文档不会保存，但是我可以使用更新后的版本将其记录到控制台中

async function checkPosts(){
        if(req.user.get("posts")){
            let posts = await req.user.get("posts");
            posts.push({
                        "Type": "Idea",
                        "Field/s of idea": req.body["Field/s of idea"],
                        "Idea": req.body.idea,
                        "Date": new Date()
                        });
            await req.user.set("posts", posts);
        }else{
            await req.user.set("posts", [{
                        "Type": "Idea",
                        "Field/s of idea": req.body["Field/s of idea"],
                        "Idea": req.body.idea,
                        "Date": new Date()
                        }]
            );
        };
        User.findOne({email:req.user.email})
            .then(user=>{
                //also tried req.user.save();
                user=req.user;
                user.save();

            })
            .catch(err=>{
                if(err) throw err
            })
    }

在猫鼬模式中未定义posts property。 这是模式：

const UserSchema = new Schema({
    _id: {type: ObjectId, auto: true},
    username: {type: String, required: true, max:18},
    email: {type: String, required: true},
    password: {type: String, required: true, min:5},
    date_of_registration: {type: Date, required: true}
}, { strict: false });