JS/Apps Script: How do I map nested keys?

May 2, 2023

In the following Google Apps Script code, I want to write three keys to the sheet key_1,key_3.subkey and key_4[1].key. How do fix my code to show the subkey and second element of key_4 as well?

function main() {

  const data = [{"key_1":10,"key_2":20,"key_3":{"subkey":30},"key_4":[{"key":41},{"key":42}]},{"key_1":40,"key_2":50,"key_3":{"subkey":60},"key_4":[{"key":43},{"key":44}]}];
  const keys = ["key_1","key_3.subkey","key_4[1].key"];


  print(data, keys);

}

function print(data, keys) {

  ss = SpreadsheetApp.getActiveSpreadsheet();
  sheet = ss.getSheetByName("Test");
  sheet.clear();

  for (let i=0; i<data.length; i++) {
    arr = Array(keys.map(k => data[i][k]));
    sheet.getRange(i+1,1,1,2).setValues(arr);
  }
}

Solution

function main() {
  const data = [{"key_1":10,"key_2":20,"key_3":{"subkey":30},"key_4":[{"key":41},{"key":42}]},{"key_1":40,"key_2":50,"key_3":{"subkey":60},"key_4":[{"key":43},{"key":44}]}];
  const keys = ["key_1","key_3.subkey","key_4.1.key"];
  print(data, keys);
}

function print(data, keys) {
  for (let i=0; i < data.length; i++) {
    let arr = keys.map(k => k.split('.').reduce((a, b) => a[b], data[i]));
    Logger.log(arr);
  }
}

>Solution :

You could use a format where all subkeys are separated by .. Then, you can split the string on . and use Array#reduce to traverse the nested data structure.

function main() {
  const data = [{"key_1":10,"key_2":20,"key_3":{"subkey":30},"key_4":["","4a"]},{"key_1":40,"key_2":50,"key_3":{"subkey":60},"key_4":["","4b"]}];
  const keys = ["key_1","key_3.subkey","key_4.1"];
  print(data, keys);
}
function print(data, keys) {
  for (let i=0; i < data.length; i++) {
    let arr = keys.map(k => k.split('.').reduce((a, b) => a[b], data[i]));
    console.log(arr);
  }
}
main();