public async Task<bool> CheckRepresentationHasChangedAsync(
Controller controller,
string representationId)
{
if (controller == null)
{
throw new ArgumentNullException(nameof(controller));
}
if (string.IsNullOrWhiteSpace(representationId))
{
throw new ArgumentNullException(nameof(representationId));
}
// Check the http request contains the header "If-None-Match"
var concatenatedEtags = controller.GetIfNoneMatch();
var modifiedSince = controller.GetModifiedSince();
var checkDateCallback = new Func<DateTime, ConcurrentObject, bool>((d, c) =>
{
return c.DateTime > d;
});
var checkEtagCorrectCallback = new Func<ConcurrentObject, List<EntityTagHeaderValue>, bool>((c, etags) =>
{
return etags.All(etag =>
{
if (etag.IsWeak)
{
// Weak etag
if (c.Etag.Contains(etag.Tag))
{
return false;
}
}
else
{
if (etag.Tag == c.Etag)
{
return false;
}
}
return true;
});
});
return await ContinueExecution(concatenatedEtags, modifiedSince, representationId, checkDateCallback, checkEtagCorrectCallback);
}