public async Task <IActionResult> ExecuteAsync(PageOptionsCursor pageOptions, CancellationToken cancellationToken)
{
DateTimeOffset?createdAfter = Cursor.FromCursor <DateTimeOffset?>(pageOptions.Before);
DateTimeOffset?createdBefore = Cursor.FromCursor <DateTimeOffset?>(pageOptions.After);
ICommandResult <PaginatedResult <Car> > result = await _mediator
.Send(new GetCarPageCommand(pageOptions.First, pageOptions.Last, createdAfter, createdBefore), cancellationToken);
switch (result.Status)
{
case CommandStatus.Unknown:
default:
throw new ArgumentOutOfRangeException(nameof(result.Status), result.Status, null);
case CommandStatus.NotFound:
return(new NotFoundResult());
case CommandStatus.Ok:
PaginatedResult <Car> paginatedResult = result.Data;
List <CarVm> carViewModels = _carMapper.MapList(paginatedResult.Items);
(string startCursor, string endCursor) = Cursor.GetFirstAndLastCursor(paginatedResult.Items, x => x.Created);
PaginatedResultVm <CarVm> paginatedResultVm = _paginatedResultFactory
.GetCursorPaginatedResult(pageOptions, paginatedResult.HasNextPage, paginatedResult.HasPreviousPage,
paginatedResult.TotalCount, startCursor, endCursor, RouteNames.GetCarPage, carViewModels);
_actionCtx.ActionContext.HttpContext
.Response.Headers.Add(CustomHeaderNames.Link, paginatedResultVm.PageInfo.ToLinkHttpHeaderValue());
return(new OkObjectResult(paginatedResultVm));
}
}
public Task <IActionResult> GetPageAsync(
[FromServices] IGetCarPageAh handler,
[FromQuery] PageOptionsCursor pageOptions,
CancellationToken cancellationToken)
{
return(handler.ExecuteAsync(pageOptions, cancellationToken));
}
private Tuple <ExpandoObject, ExpandoObject> GetCursorUniqueQueryParams(PageOptionsCursor pageOptions)
{
ExpandoObject uniqueParams = new ExpandoObject();
ExpandoObject apiVersionParam = new ExpandoObject();
foreach (KeyValuePair <string, StringValues> item in _actionCtx.ActionContext.HttpContext.Request.Query)
{
string key = item.Key.ToLowerInvariant();
if (key != nameof(pageOptions.First).ToLowerInvariant() &&
key != nameof(pageOptions.Last).ToLowerInvariant() &&
key != nameof(pageOptions.Before).ToLowerInvariant() &&
key != nameof(pageOptions.After).ToLowerInvariant())
{
if (key == ApiVersionQueryKey)
{
apiVersionParam.TryAdd(key, item.Value);
}
else
{
uniqueParams.TryAdd(key, item.Value);
}
}
}
return(new Tuple <ExpandoObject, ExpandoObject>(uniqueParams, apiVersionParam));
}
public PaginatedResultVm <T> GetCursorPaginatedResult <T>(PageOptionsCursor pageOptions, bool hasNextPage, bool hasPreviousPage,
int totalCount, string startCursor, string endCursor, string routeName, ICollection <T> items) where T : class
{
ArgumentNullException.ThrowIfNull(pageOptions);
if (string.IsNullOrEmpty(routeName))
{
throw new ArgumentNullException(nameof(routeName));
}
ICollection <T> resultItems = items ?? new List <T>();
Tuple <ExpandoObject, ExpandoObject> baseQueryParams = GetCursorUniqueQueryParams(pageOptions);
PageInfoVm pageInfo = new PageInfoVm()
{
Count = items.Count,
HasNextPage = hasNextPage,
HasPreviousPage = hasPreviousPage,
NextPageUrl = hasNextPage ? GetCursorNextPageUri(routeName, baseQueryParams, pageOptions, endCursor) : null,
PreviousPageUrl = hasPreviousPage ? GetCursorPreviousPageUri(routeName, baseQueryParams, pageOptions, startCursor) : null,
FirstPageUrl = GetCursorFirstPageUri(routeName, baseQueryParams, pageOptions),
LastPageUrl = GetCursorLastPageUri(routeName, baseQueryParams, pageOptions),
};
PaginatedResultVm <T> result = new PaginatedResultVm <T>(totalCount, pageInfo, resultItems);
return(result);
}
private Uri GetCursorNextPageUri(string routeName, Tuple <ExpandoObject, ExpandoObject> baseUrlParams, PageOptionsCursor pageOptions, string endCursor)
{
ExpandoObject baseParams = CopyUniqueQueryParams(baseUrlParams.Item1);
baseParams.TryAdd(nameof(pageOptions.First), pageOptions.First ?? pageOptions.Last);
baseParams.TryAdd(nameof(pageOptions.After), endCursor);
return(GenerateLink(routeName, baseParams, baseUrlParams.Item2));
}
