对嵌套的对象数组进行排序 [英] Sort nested array of objects

问题描述

我正在寻找一种对嵌套对象数组进行排序的方法.

I'm looking for a way to sort a nested array of objects.

这是一个例子:

{
  answers : [
    { name : 'paul',  state : 'RU' },
    { name : 'steve', state : 'US' }, 
    { name : 'mike',  state : 'DE' }, 
    ...
  ]
}

假设现在我想找到 answers 数组的所有 name，但我如何按升序对它们进行排序?

Suppose now I want to find all the name, of the answers array, but how can I sort them in ascending order?

推荐答案

我会按照你想要的顺序存储它.或者拉出来后排序，在客户端.

I would store it in the order you want it back out. Or sort it after you pull it out, on the client side.

如果这两个都不可能，您可以使用聚合框架:

If neither of those are possible, you can use the aggregation framework:

> db.test.insert({answers: [
...                 {name: 'paul', state: 'RU'},
...                 {name: 'steve', state: 'US'}, 
...                 {name: 'mike', state: 'DE'}]});
> db.test.insert({answers: [
...                 {name: 'paul', state: 'RU'},
...                 {name: 'steve', state: 'US'}, 
...                 {name: 'xavier', state: 'TX'}]});

db.test.aggregate([
  {$unwind: "$answers"}, 
  {$sort: {"answers.name":1}}, 
  {$group: {_id:"$_id", answers: {$push:"$answers"}}}
]);

产生:

{
  "result" : [
  {
    "_id" : ObjectId("5053b2477d820880c3469364"),
    "answers" : [
      {
        "name" : "paul",
        "state" : "RU"
      },
      {
        "name" : "steve",
        "state" : "US"
      },
      {
        "name" : "xavier",
        "state" : "TX"
      }
    ]
  },
  {
    "_id" : ObjectId("5053af9f7d820880c3469363"),
    "answers" : [
      {
        "name" : "mike",
        "state" : "DE"
      },
      {
        "name" : "paul",
        "state" : "RU"
      },
      {
        "name" : "steve",
        "state" : "US"
      }
    ]
  }
],
  "ok" : 1
}

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