猫鼬:在保存时根据父字段值设置子文档字段值 [英] Mongoose: Set subdocument field value based on parent field value on save

问题描述

几乎可以肯定在其他地方有介绍，但是:

This is almost certainly covered elsewhere, but:

如果我有一个带有嵌入式子文档的架构，例如:

If I have a single schema with an embedded sub-document, like so:

var ChildSchema = new Schema ({
name : {
        type: String, 
        trim: true
},
user :{
    type: String, 
    trim: true
}
})

var ParentSchema = new Schema ({
name : {
     type: String,
     trim: true
},
child : [ChildSchema]
})

如何在同一.save()操作中将ParentSchema的名称保存为ParentSchema.name和ChildSchema.name?以下内容根本不起作用.

How would I save the name of the ParentSchema to ParentSchema.name and to ChildSchema.name in the same .save() action? The following does not work at all.

ChildSchema.pre('save', function(next){
this.name = ParentSchema.name;
next();
});

推荐答案

您可以通过将中间件移动到ParentSchema来进行访问，该中间件可以访问其自身及其子级:

You can do that by moving the middleware to ParentSchema which has access to itself and its children:

ParentSchema.pre('save', function(next){
    var parent = this;
    this.child.forEach(function(child) {
        child.name = parent.name;
    });
    next();
});

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