node.js 中的 JSON 迭代

Question

[
  {
    "Hs": 5,
    "Type": "Support",
    "By": "William Shake the Speare",
    "Product": "SA",
    "Customer": "Huxley",
    "State": "In progress"
  },
  {
    "Hs": 2,
    "Type": "Support",
    "By": "Orwells",
    "Product": "Web",
    "Customer": "Infranet",
    "State": "Closed"
  }]

I have many of this objects and need to take Customer and sum (add) all of his "Hs" value. So the final array would be like:

[
{
    "Customer" : "Infranet",
    "Total_hs" : "18" 
},
{
    "Customer" : "Huxley",
    "Total_hs" : "11" 
}
]

I tried to find out with lodash and node foreach functions but can't, could you help me please? Thanks!

Answer 1

First, you must make sure you have the input data as a javascript object (so if it is a json string, it will need to be parsed with something like var items = JSON.parse(input_string) )

var items = [{
  "Hs": 5,
  "Type": "Support",
  "By": "William Shake the Speare",
  "Product": "SA",
  "Customer": "Huxley",
  "State": "In progress"
}, {
  "Hs": 2,
  "Type": "Support",
  "By": "Orwells",
  "Product": "Web",
  "Customer": "Infranet",
  "State": "Closed"
}]

... next, create array of summed Hs values...

var totals = _.reduce(items, function(memo, item) {
  // make sure that the customer is created on the output object, or initialise it to zero
  memo[item.Customer] = memo[item.Customer] || 0;
  // increment the Hs value with the current item's Hs value
  memo[item.Customer] += item.Hs;
  // return the current object for the next iteration of the loop
  return memo;
// pass empty object to initialise reduce
}, {});

totals should now have array of objects, with customer name as key, and total Hs as value.

... next, reformat array to match desired data format...

var target_array = _.map(totals, function(item, key) {
  return {
    Customer: key,
    Total_hs: item
  }
});

... check the out put is correct...

console.log(target_array);

Answer 2

Given the JSON is provided as a JavaScript object ( items in the sample below):

var items = [{
    "Hs": 5,
    "Type": "Support",
    "By": "William Shake the Speare",
    "Product": "SA",
    "Customer": "Huxley",
    "State": "In progress"
  }, {
    "Hs": 2,
    "Type": "Support",
    "By": "Orwells",
    "Product": "Web",
    "Customer": "Infranet",
    "State": "Closed"
}];
var collected = _.map(_.keys(_.grouped(items, "Customer")), function(k) {
  return {
    Customer: k,
    Hs: _.reduce(grouped[k], function(accumulator, v) {
        return accumulator + v.Hs;
      }, 0)
  };
});