diff static method

List<Map<String, dynamic>> diff(dynamic oldJson, dynamic newJson)

Performs a diff-algorithm on two JSON-like objects.

Returns a JSON-like List of JSON Patch operations to get from oldJson to newJson. May throw a JsonPatchError if something goes wrong.

See https://tools.ietf.org/html/rfc6902 for more information.

Implementation

static List<Map<String, dynamic>> diff(dynamic oldJson, dynamic newJson) {
  try {
    // If both objects are null, no patch is required.
    if (oldJson == null && newJson == null) {
      return [];
    }

    // If the object was either null before or set to null now, replace the value.
    if (oldJson == null || newJson == null) {
      return [
        {'op': 'replace', 'path': '', 'value': newJson}
      ];
    }

    // If the parameters are Maps, call the specialized function for objects.
    if (oldJson is Map<String, dynamic> && newJson is Map<String, dynamic>) {
      return _objectDiff(oldJson, newJson);
    }

    // If the parameters are List, call the specialized function for lists.
    if (oldJson is List && newJson is List) {
      return _listDiff(oldJson, newJson);
    }

    // If the runtime type changed, replace the value.
    if (oldJson.runtimeType != newJson.runtimeType) {
      return [
        {'op': 'replace', 'path': '', 'value': newJson}
      ];
    }

    // For primitive types, use the == operator for comparison and replace if necessary.
    if (oldJson != newJson) {
      return [
        {'op': 'replace', 'path': '', 'value': newJson}
      ];
    }

    // No difference found.
    return [];
  } catch (e) {
    throw JsonPatchError('An unknown error occurred.');
  }
}