Question

我有一个如下数组：

var result=[{"id": 1, "details": [{"ah": 1.0, "dId": 11},{"ah": 2.0, "dId": 11}, {"ah": 2.0, "dId": 12}]}, {"id": 2, "details": [{"ah": 1.0, "dId": 11},{"ah": 2.0, "dId": 11}]}]

现在我想使用underscore.js通过Id和dId属性过滤它，例如。给我id = 1和dId = 11的所有细节，并做了一个ah属性的总和。所以，例如。过滤id = 1和dId = 11应返回3.

我尝试过这样的事情：_.where(result, {id: 1, details.dId:11})

但我无法让它发挥作用。

我创造了一个小提琴： http://jsfiddle.net/j9Htk/

感谢任何帮助

感谢

托马斯

Answer 1

首先过滤结果以获得具有匹配id的那些（可以处理具有相同id的那个）：

var filteredList = _.filter(result, function(value){
    return value.id == 1;
});

现在总结所有的啊：

var sum = _.reduce(filteredList , function(memo, value){

    // find all details that have a matching dId
    var details = _.filter(value.details, function(detail){ return detail.dId == 11; });

    // return the sum of all the found details
    return memo + _.reduce(details, function(memo2, detail){ return memo2 + detail.ah; }, 0);

}, 0);

Answer 2

我是下划线的初学者，这是我的尝试：

var result=[{"id": 1, "details": [{"ah": 1.0, "dId": 11},{"ah": 2.0, "dId": 11}, {"ah": 2.0, "dId": 12}]}, {"id": 2, "details": [{"ah": 1.0, "dId": 11},{"ah": 2.0, "dId": 11}]}];


function calculate( result, id, dId ){

      var sum = 0;
      _.each( result[id].details, function( detail ){
        if( detail.dId == dId ){
            sum += detail.ah;
        }
      });

      console.log( 'id: ' + id + ' sum: ' + sum );
}

calculate( result,1,11 );

Answer 3

function extractSumOfAhs(result, id, dId) {
  return _.reduce(
    _.pluck(
      _.where(
        _.flatten(
          _.pluck(
            _.where(
              result,
              { id: id }
            ),
            "details"
          )
        ),
        {dId: dId}
      ),
      "ah"
    ),
    function(a,b) { return a + b; }
  )
}

或与链：

function extractSumOfAhs(result, id, dId) {
  return _.chain(result)
    .where({id : id})
    .pluck("details")
    .flatten()
    .where({dId : dId})
    .pluck("ah")
    .reduce(function(a, b) { return a + b;})
    .value()  
}

使用underscore.js按子数组中的属性进行过滤

3 个答案: