Node.js Mongoose-如何使用预钩子移除级联删除

我有一个矩模式，它可以有多个相关联的注释。当某个时刻被删除时，我希望所有与该时刻相关的评论也被删除

动量图式

let MomentSchema = new Schema({

    body: String,
    likes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    dislikes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    comments: [{
        type: Schema.Types.ObjectId,
        ref: 'Comment',
    }],
    author: {
        type: Schema.Types.ObjectId,
        ref: 'User',
    },

},
    {
        timestamps: {createdAt: 'created_at', updatedAt: 'updated_at'},
    });

MomentSchema.pre('remove', (next) => {

//What to include here to delete all the comments for this moment

});

let CommentSchema = new Schema({

    body: {
        type: String,
        required: true,
    },
    moment: {
        type: Schema.Types.ObjectId,
        ref: 'Moment',
    },
    author: {
        type: Schema.Types.ObjectId, ref: 'User',
        required: true,
    },
    likes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    dislikes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    parent: {
        type: Schema.Types.ObjectId, 
        ref: 'Comment',
    },
    replies: [{
        type: Schema.Types.ObjectId,
        ref: 'Comment',
    }],

},
    {
        timestamps: {createdAt: 'created_at', updatedAt: 'updated_at'},
    });

仅供参考，一条评论也可以有一个回复，这也是一个评论模型，因此我还需要在评论模型中添加一个pre-remove钩子

注释模式

let MomentSchema = new Schema({

    body: String,
    likes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    dislikes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    comments: [{
        type: Schema.Types.ObjectId,
        ref: 'Comment',
    }],
    author: {
        type: Schema.Types.ObjectId,
        ref: 'User',
    },

},
    {
        timestamps: {createdAt: 'created_at', updatedAt: 'updated_at'},
    });

MomentSchema.pre('remove', (next) => {

//What to include here to delete all the comments for this moment

});

let CommentSchema = new Schema({

    body: {
        type: String,
        required: true,
    },
    moment: {
        type: Schema.Types.ObjectId,
        ref: 'Moment',
    },
    author: {
        type: Schema.Types.ObjectId, ref: 'User',
        required: true,
    },
    likes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    dislikes: [{
        type: Schema.Types.ObjectId,
        ref: 'User',
    }],
    parent: {
        type: Schema.Types.ObjectId, 
        ref: 'Comment',
    },
    replies: [{
        type: Schema.Types.ObjectId,
        ref: 'Comment',
    }],

},
    {
        timestamps: {createdAt: 'created_at', updatedAt: 'updated_at'},
    });

API删除：时刻/：id

 destroy(req, res) {

        let id = req.params.id;

        Moment.findOne({'_id': id}, (err, moment) => {

            if (err) {

                return res.status(404).json({

                    success: false,
                    status: 404,
                    data: {},
                    message: 'Failed to find moment',

                });

            }

            moment.remove((err, moment) => {

                if (err) {
                    return res.status(400).json({
                        success: false,
                        status: 400,
                        data: err,
                        message: 'Failed to delete moment',
                    });
                }

                return res.status(200).json({

                    success: true,
                    status: 200,
                    data: {},
                    message: 'Successfully deleted moment',

                });

            });


        });

}

---

我需要在pre-hook中删除什么才能删除与该时刻相关的所有注释。此外，当在预钩子移除中调用“this”时，它返回未定义。

因此要移除所有注释和多级级联，我必须调用文档上的.remove方法。将下面的代码插入力矩预钩移除函数，它将在移除力矩之前删除注释

此外，在删除注释之前，它将调用注释前钩子。在这里，我可以添加代码来删除对每条评论的回复

 Comment.find({'moment': this._id})
        .then((comments) => {
            Promise.all(comments.forEach((comment) => comment.remove()))
                .then(next());
        });

---

此处使用了promise.all，因为我们只想在删除所有注释后删除该时刻

，因此要删除所有注释和多级级联，我必须调用文档上的.remove方法。将下面的代码插入力矩预钩移除函数，它将在移除力矩之前删除注释

此外，在删除注释之前，它将调用注释前钩子。在这里，我可以添加代码来删除对每条评论的回复

 Comment.find({'moment': this._id})
        .then((comments) => {
            Promise.all(comments.forEach((comment) => comment.remove()))
                .then(next());
        });

此处使用的是promise.all，因为我们只想在删除所有评论后删除该时刻