create and count dynamic object in typescript

Question

I am trying to compute a result from an array for objects that I can count how many values for each key and add its own dbId to the same computed result within the object name! the reason behind that is to use it to chart.js. so I can check each result value comes with its own dbIds

const obj = [
  {
    dbId: 26598,
    properties: [
      { attributeName: "BIM7AATypeCode" },
      { displayCategory: "Identity Data" },
      { displayName: "BIM7AATypeCode" },
      { displayValue: "221" },
    ],
  },
  {
    dbId: 26591,
    properties: [
      { attributeName: "BIM7AATypeCode" },
      { displayCategory: "Identity Data" },
      { displayName: "BIM7AATypeCode" },
      { displayValue: "221" },
    ],
  },
  {
    dbId: 3695,
    properties: [
      { attributeName: "abc" },
      { displayCategory: "Identity Data" },
      { displayName: "BIM7AATypeCode" },
      { displayValue: "123" },
    ],
  },
  {
    dbId: 3697,
    properties: [
      { attributeName: "abc" },
      { displayCategory: "Identity Data" },
      { displayName: "BIM7AATypeCode" },
      { displayValue: "123" },
    ],
  },
];

// type Histogram = {
//   [key: string]: number;
// };

let histogram = {}; //as Histogram

for (let iterator of obj) {
  for (let { displayName, displayValue } of iterator.properties) {
    //@ts-ignore
    histogram[displayName] = histogram[displayName] | {};

    if (!histogram[displayValue]) {
      histogram[displayValue] = 1;
    } else {
      histogram[displayValue] = histogram[displayValue] + 1;
    }
  }
}

console.log(histogram);

//expected result:

/*

{
  BIM7AATypeCode: {
    "221": 2,
    dbid: [26598, 26591],
  },
  abc: {
    "123": 2,
    dbid: [3695, 3697],
  },
};
*/

Answer 1

Please find the Array.reduce implementation.

Logic

• Loop through obj array using Array.reduce
• From each object in the array, pick the properties key. From this select node having key attributeName which is attribute node and with displayValue which is display value node.
• Check whether the accumulator has a node with the attributeName.
• If not, push a node to accumulator, with the displayValue having vale 1 and dbid as a single noded array.
• If accumulator already have this node. Update the count of displayValue and push the new dbid

const obj = [
  { dbId: 26598, properties: [{ attributeName: "BIM7AATypeCode" }, { displayCategory: "Identity Data" }, { displayName: "BIM7AATypeCode" }, { displayValue: "221" }] },
  { dbId: 26591, properties: [{ attributeName: "BIM7AATypeCode" }, { displayCategory: "Identity Data" }, { displayName: "BIM7AATypeCode" }, { displayValue: "221" }] },
  { dbId: 3695, properties: [{ attributeName: "abc" }, { displayCategory: "Identity Data" }, { displayName: "BIM7AATypeCode" }, { displayValue: "123" }] },
  { dbId: 3697, properties: [{ attributeName: "abc" }, { displayCategory: "Identity Data" }, { displayName: "BIM7AATypeCode" }, { displayValue: "123" }] },
];
const output = obj.reduce((acc, curr) => {
  const attribute = curr.properties.find(node => node.attributeName);
  const displayValue = curr.properties.find(node => node.displayValue);
  if (acc[attribute.attributeName]) {
    acc[attribute.attributeName][displayValue.displayValue] ? acc[attribute.attributeName][displayValue.displayValue]++ : acc[attribute.attributeName][displayValue.displayValue] = 1;
    acc[attribute.attributeName].dbid.push(curr.dbId);
  } else {
    const newAttribute = {
      [displayValue.displayValue]: 1,
      dbid: [curr.dbId]
    }
    acc[attribute.attributeName] = newAttribute;
  }
  return acc;
}, {});
console.log(output);