下划线对嵌套数组进行分组和排序

Question

使用 meteor，我有一个 mongo 聚合返回一个反应性变量，如下所示：

[{
"_id": "game1",
"playerpicks": [
  {
    "player": "Chris",
    "pick": "atsa"
  },
  {
    "player": "al",
    "pick": "suh"
  },
  {
    "player": "al",
    "pick": "atsh"
  },
  {
    "player": "Chris",
    "pick": "sua"
  }]  },{
"_id": "game2",
"playerpicks": [
  {
    "player": "al",
    "pick": "atsa"
  },
  {
    "player": "Chris",
    "pick": "suh"
  },
  {
    "player": "Chris",
    "pick": "atsh"
  },
  {
    "player": "al",
    "pick": "sua"
  }]  },  ....  ]

我需要将这些数据转换成理想情况下如下所示的网格：

GAME       al          Chris
game1    suh/atsh      sua/atsa
game2    sua/atsa      suh/atsh

假设这是一个太大的挑战，我可以做这样的事情：

game 1    al: suh/atsh     Chris:  sua/atsa
game 2    al: sua/atsa     Chris:  suh/atsh

我看到 Mongo 需要在客户端进行排序，所以我专注于使用下划线，但即使在 _.sortBy 或 _.groupBy 嵌套数组 "playerpicks"

我试过如下：

_.each(monArr, function(obj){ _.each(obj.playerpicks, function(nst){ _.groupBy( nst.player ) }) })

以及：

_.groupBy(monArr, function(obj){return obj.playerpicks.player})

但我还差得远呢。没有数据返回。非常感谢任何建议

Answer 1

这是一个使用无数下划线函数的解决方案，分解成离散的块，希望能使其更具可读性：

// helper function to combine a player's picks into a string delimited by '/'
let combinePicks = player => _.pluck(player, 'pick').join('/');

// helper function to group a game by a player
let groupGame = game => _.chain(game.playerpicks)
    .groupBy('player')
    .mapObject(combinePicks)
    .value();

// map the data to create the object in the required form
let result = _.map(data, game => _.extend({GAME: game._id}, groupGame(game) ));

对于不支持 mapObject（1.8 之前）的早期版本的下划线，可以使用 reduce:

实现相同的结果

let combinePicks = function(memo, player, key){
    memo[key] = _.pluck(player, 'pick').join('/');
    return memo;
} 

let groupGame = game => _.chain(game.playerpicks)
    .groupBy('player')
    .reduce(combinePicks, {})
    .value();

  var data = [{
"_id": "game1",
"playerpicks": [
  {
    "player": "Chris",
    "pick": "atsa"
  },
  {
    "player": "al",
    "pick": "suh"
  },
  {
    "player": "al",
    "pick": "atsh"
  },
  {
    "player": "Chris",
    "pick": "sua"
  }]  },{
"_id": "game2",
"playerpicks": [
  {
    "player": "al",
    "pick": "atsa"
  },
  {
    "player": "Chris",
    "pick": "suh"
  },
  {
    "player": "Chris",
    "pick": "atsh"
  },
  {
    "player": "al",
    "pick": "sua"
  }]  }
 ];

 let combinePicks = player => _.pluck(player, 'pick').join('/');

 let groupGame = game => _.chain(game.playerpicks)
  .groupBy('player')
  .mapObject(combinePicks)
  .value();
 
 let result = _.map(data, game => _.extend({GAME: game._id}, groupGame(game) ));


document.getElementById('result').textContent = JSON.stringify(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>

<p>
  <pre id="result"></pre>
</p>

下划线对嵌套数组进行分组和排序

Underscore group and sort nested arrays

multidimensional-array

mongodb

underscore.js