calculateDelta static method

Map<String, dynamic> calculateDelta(Map<String, dynamic> oldDocument, Map<String, dynamic> newDocument)

Calculate which fields changed between old and new versions.

Returns only the fields that are different.

Example:

final oldDoc = {'title': 'Old', 'done': false, 'priority': 5};
final newDoc = {'title': 'Old', 'done': true, 'priority': 5};

final delta = DeltaCalculator.calculateDelta(oldDoc, newDoc);
// Returns: {'done': true}

Implementation

static Map<String, dynamic> calculateDelta(
  Map<String, dynamic> oldDocument,
  Map<String, dynamic> newDocument,
) {
  final delta = <String, dynamic>{};

  // Check for changed or new fields
  for (final key in newDocument.keys) {
    final oldValue = oldDocument[key];
    final newValue = newDocument[key];

    if (!_areEqual(oldValue, newValue)) {
      delta[key] = newValue;
    }
  }

  // Check for removed fields (set to null)
  for (final key in oldDocument.keys) {
    if (!newDocument.containsKey(key)) {
      delta[key] = null;
    }
  }

  return delta;
}