Dart Requires Chilkat v11.0.0+

Modify Parts of JSON Document

See more JSON Examples

Demonstrates how to modify parts of a JSON document. This example uses the following JSON document:

{
   "fruit": [
      	{
         "kind": "apple",
	 "count": 24,
	 "fresh": true,
	 "extraInfo": null,
	 "listA": [ "abc", 1, null, false ],
	 "objectB": { "animal" : "monkey" }
      	},
	{
         "kind": "pear",
	 "count": 18,
	 "fresh": false,
	 "extraInfo": null
	 "listA": [ "xyz", 24, null, true ],
	 "objectB": { "animal" : "lemur" }
	}
    ],
    "list" : [ "banana", 12, true, null, "orange", 12.5, { "ticker": "AAPL" }, [ 1, 2, 3, 4, 5 ] ],
    "alien" : true
}

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final json = CkJsonObject();

  // Load the JSON from a file.
  try {
    json.loadFile('qa_data/json/modifySample.json');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // This example will not check for errors (i.e. null / false / 0 return values)...

  // Get the "list" array:

  final listA = CkJsonArray();

  json.arrayOf2('list', listA);

  // Modify values in the list.

  // Change banana to plantain
  listA.setStringAt(0, 'plantain');

  // Change 12 to 24
  listA.setIntAt(1, 24);

  // Change true to false
  listA.setBoolAt(2, false);

  // Is the 3rd item null?

  // Change "orange" to 32.
  listA.setIntAt(4, 32);

  // Change 12.5 to 31.2
  listA.setNumberAt(5, '31.2');

  // Replace the { "ticker" : "AAPL" } object with { "ticker" : "GOOG" }
  // Do this by deleting, then inserting a new object at the same location.
  listA.deleteAt(6);
  final tickerObj = CkJsonObject();
  listA.addObjectAt2(6, tickerObj);

  tickerObj.appendString('ticker', 'GOOG');

  // Replace "[ 1, 2, 3, 4, 5 ]" with "[ "apple", 22, true, null, 1080.25 ]"
  listA.deleteAt(7);
  final aa = CkJsonArray();
  listA.addArrayAt2(7, aa);

  aa.addStringAt(-1, 'apple');
  aa.addIntAt(-1, 22);
  aa.addBoolAt(-1, true);
  aa.addNullAt(-1);
  aa.addNumberAt(-1, '1080.25');

  // Get the "fruit" array
  final aFruit = CkJsonArray();
  json.arrayAt2(0, aFruit);

  // Get the 1st element:
  final appleObj = CkJsonObject();
  aFruit.objectAt2(0, appleObj);

  // Modify values by member name:
  appleObj.setStringOf('fruit', 'fuji_apple');
  appleObj.setIntOf('count', 46);
  appleObj.setBoolOf('fresh', false);
  appleObj.setStringOf('extraInfo', 'developed by growers at the Tohoku Research Station in Fujisaki');

  // Modify values by index:

  final pearObj = CkJsonObject();
  aFruit.objectAt2(1, pearObj);

  pearObj.setStringAt(0, 'bartlett_pear');
  pearObj.setIntAt(1, 12);
  pearObj.setBoolAt(2, false);
  pearObj.setStringAt(3, 'harvested in late August to early September');

  json.emitCompact = false;
  print(json.emit());
}