node.js - Mongoose - 如何在 Mongoose 中的填充字段数组中选择特定对象？

Question

我已经在 Mongoose 中填充了一个虚拟，填充的虚拟将检索一个对象数组。

 objects:{[name:'xxx',age:20],[name:'yyy',age:21],[name:'zzz', age:23]}

如何使其只检索我指定的一个元素？

...
.populate({
   path:'someVirtual',
   select:'objects', //get only the 'objects' array
   options: {where:'objects',elemMatch:{name:'zzz'}} //this is what I tried 
                                                     //but it doesn't work
  )}
 .exec(function(err,docs){
    //handle
  });

Answer 1

您可以在填充中使用match

.populate({
   path:'someVirtual',
   match: { objects: { $elemMatch: { name: 'zzz' } } },
   select: 'objects'                                        
})

如果你想使用投影那么

.populate({
   path:'someVirtual',
   match: { objects: { $elemMatch: { name: 'zzz' } } },
   select: { objects: { $elemMatch: { name: 'zzz' } } }                                   
})