var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var SubSchema = new Schema( { x : Number } );
SubSchema.pre('save',function (next) {
  console.log("pre save Sub");
  next();
});

var MainSchema = new Schema( { x : Number,children : [SubSchema] } );
MainSchema.pre('save',function (next) {
  console.log("pre save Main");
  next();
});
var Main = mongoose.model('Main',MainSchema);

var m = new Main();
m.children.push( { x : 42 } );

m.save( function(err,doc) {
  console.log(doc +"\n\n");
  doc.children[0].x = 43;

  doc.save( function(err,doc2) {
    console.log(doc2 + "\n\n");
  });
});

当我运行此代码时,我得到以下输出：

pre save Sub
pre save Main
{ __v: 0,_id: 50660b319aec895a50000002,children: [ { x: 42,_id: 50660b319aec895a50000003 } ] }


pre save Main
{ __v: 0,children: [ { x: 43,_id: 50660b319aec895a50000003 } ] }

在第二次保存操作的子文档没有运行预保存挂钩的任何原因？