Chart.js中带有JSON数据的堆叠条形图

Question

I have following JSON data.

[
  {
      "date": "2016-05-01T00:00:00",
      "productInformation": [
        {
            "productName": "Apple",
            "totalWeight": 200
        }
      ]
  },
  {
      "date": "2016-09-01T00:00:00",
      "productInformation": [
        {
            "productName": "Apple",
            "totalWeight": 632
        },
        {
            "productName": "Mango",
            "totalWeight": 856
        },
        {
            "productName": "Spinach",
            "totalWeight": 545
        },
        {
            "productName": "Grapes",
            "totalWeight": 338
        }
      ]
  },
  {
      "date": "2017-01-01T00:00:00",
      "productInformation": [
        {
            "productName": "Mango",
            "totalWeight": 500
        }
      ]
  }
]

On X axis I want to display Month and year and on Y axis I want to display stacked bar of product information. for example in 2016-05 there is only Apple so it will only display apple. In 2016-09 there are 4 products so it will display 4 staked bar according to 4 products and its total weight. I have read chart.js documentation. According to documentation I have to provide Y axis values in dataset. How do I extract Y axis values for dataset to create stacked bar from given JSON data? If I want to create chart manually from JSON data given above then it would be something like this.

var barChartData = {
labels: ["May 2016", "September 2016", "January 2017"],
datasets: [{
    label: "Apple",
    data: [200, 632, 0],
    backgroundColor: "#3c8dbc"
},
{
    label: "Mango",
    data: [0,856,500],
    backgroundColor: "#3c8dbc"
},
{
    label: "Spinach",
    data: [0,545,0],
    backgroundColor: "#3c8dbc"
},
{
    label: "Grapes",
    data: [0,338,0],
    backgroundColor: "#3c8dbc"
}]
};

I need a way to extract data part of dataset from given JSON data.

Answer 1

This snippet should solve the hardest part of your problem (using ES6 syntax):

 const data = [{ "date": "2016-05-01T00:00:00", "productInformation": [{ "productName": "Apple", "totalWeight": 200 }] }, { "date": "2016-09-01T00:00:00", "productInformation": [{ "productName": "Apple", "totalWeight": 632 }, { "productName": "Mango", "totalWeight": 856 }, { "productName": "Spinach", "totalWeight": 545 }, { "productName": "Grapes", "totalWeight": 338 }] }, { "date": "2017-01-01T00:00:00", "productInformation": [{ "productName": "Mango", "totalWeight": 500 }] }] const uniq = a => [...new Set(a)] const flatten = a => [].concat.apply([], a) // step 1: find the distinct dates: ["2016-05-01T00:00:00", ... ] const dates = data.map(e => e.date) // step 2: find the distinct labels: [Apple, Mango, ... ] const labels = uniq( flatten(data.map(e => e.productInformation)) .map(e => e.productName)) // step 3: map the labels to entries containing their data by searching the original data array const result = labels.map(label => { return { label, data: dates.map(date => { const hit = data.find(e => e.date === date) .productInformation .find(p => p.productName === label) return hit ? hit.totalWeight : 0 }) } }) console.log(result)