JsonPatchExtensions

  public static class JsonPatchDocumentExtensions
    {
        public static Result Apply<TModel>(this JsonPatchDocument<TModel> jsonPatchDocument, TModel model) where TModel : class
        {
            Result applyingResult = Result.Ok();
            void InCaseOfError(JsonPatchError jsonPatchError) => applyingResult = Result.Failure(jsonPatchError.ErrorMessage);
            jsonPatchDocument.ApplyTo(model, InCaseOfError);
            return applyingResult;
        }
        public static Result<TModel, AppError> ApplyOps<TModel>(this JsonPatchDocument<TModel> jsonPatchDocument, TModel model) where TModel : class
        {
            Result<TModel, AppError> applyingResult = Result.Success<TModel, AppError>(model);
            void InCaseOfError(JsonPatchError jsonPatchError) => applyingResult = Result.Failure<TModel, AppError>(new AppError(jsonPatchError.ErrorMessage));
            jsonPatchDocument.ApplyTo(model, InCaseOfError);
            return applyingResult
                .Map(_ => model);
        }

        public static bool ModifiesProperty<TModel>(this JsonPatchDocument<TModel> document, string propertyName)
            where TModel : class
            => propertyName.Exists() && document.GetUpdatingProperties().Contains(propertyName);

        public static T GetUpdatedValue<TModel, T>(this JsonPatchDocument<TModel> document, string propertyName)
            where TModel : class
        {
            var op = document.Operations.Find(op => op.path.Replace("/", string.Empty).Equals(propertyName));
            return JsonConvert.DeserializeObject<T>(JsonConvert.SerializeObject(op.value));
        }

        public static string[] GetUpdatingProperties(this IJsonPatchDocument jsonPatchDocument)
            => jsonPatchDocument.GetOperations().Select(op => op.path.Replace("/", string.Empty)).ToArray();

        public static HashSet<string> GetUpdatedProperties<TTarget>(this JsonPatchDocument<TTarget> jsonPatchDocument)
            where TTarget : class => GetUpdatingProperties(jsonPatchDocument)
            .Select(GetRealPropertyName<TTarget>)
            .ToHashSet();

        private static string GetRealPropertyName<TTarget>(string jsonPropertyName)
        {
            PropertyInfo matchingProperty = typeof(TTarget)
                .GetProperties(BindingFlags.Public | BindingFlags.Instance)
                .FirstOrDefault(prop => prop.Name.Equals(jsonPropertyName) || HasJsonPropertyAttribute(prop, jsonPropertyName));
            return matchingProperty.Name;
        }

        private static bool HasJsonPropertyAttribute(PropertyInfo propInfo, string jsonPropName)
        {
            JsonPropertyAttribute attribute = propInfo.GetCustomAttribute<JsonPropertyAttribute>();
            if (attribute == null)
                return false;
            return attribute.PropertyName.Exists() &&
                   attribute.PropertyName.Equals(jsonPropName, StringComparison.OrdinalIgnoreCase);
        }