private DynamicPageEndpointSelector ResolveSelector(DynamicPageEndpointSelector currentSelector, Endpoint endpoint)
{
var selector = _selectorCache.GetEndpointSelector(endpoint);
Debug.Assert(currentSelector == null || ReferenceEquals(currentSelector, selector));
return(selector);
}
public DynamicPageEndpointMatcherPolicy(DynamicPageEndpointSelector selector, PageLoader loader)
{
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
if (loader == null)
{
throw new ArgumentNullException(nameof(loader));
}
_selector = selector;
_loader = loader;
}
public async Task ApplyAsync(HttpContext httpContext, CandidateSet candidates)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
if (candidates == null)
{
throw new ArgumentNullException(nameof(candidates));
}
DynamicPageEndpointSelector selector = null;
// There's no real benefit here from trying to avoid the async state machine.
// We only execute on nodes that contain a dynamic policy, and thus always have
// to await something.
for (var i = 0; i < candidates.Count; i++)
{
if (!candidates.IsValidCandidate(i))
{
continue;
}
var endpoint = candidates[i].Endpoint;
var originalValues = candidates[i].Values;
RouteValueDictionary dynamicValues = null;
// We don't expect both of these to be provided, and they are internal so there's
// no realistic way this could happen.
var dynamicPageMetadata = endpoint.Metadata.GetMetadata <DynamicPageMetadata>();
var transformerMetadata = endpoint.Metadata.GetMetadata <DynamicPageRouteValueTransformerMetadata>();
DynamicRouteValueTransformer transformer = null;
if (dynamicPageMetadata != null)
{
dynamicValues = dynamicPageMetadata.Values;
}
else if (transformerMetadata != null)
{
transformer = (DynamicRouteValueTransformer)httpContext.RequestServices.GetRequiredService(transformerMetadata.SelectorType);
if (transformer.State != null)
{
throw new InvalidOperationException(Resources.FormatStateShouldBeNullForRouteValueTransformers(transformerMetadata.SelectorType.Name));
}
transformer.State = transformerMetadata.State;
dynamicValues = await transformer.TransformAsync(httpContext, originalValues);
}
else
{
// Not a dynamic page
continue;
}
if (dynamicValues == null)
{
candidates.ReplaceEndpoint(i, null, null);
continue;
}
selector = ResolveSelector(selector, endpoint);
var endpoints = selector.SelectEndpoints(dynamicValues);
if (endpoints.Count == 0 && dynamicPageMetadata != null)
{
// Having no match for a fallback is a configuration error. We can't really check
// during startup that the action you configured exists, so this is the best we can do.
throw new InvalidOperationException(
"Cannot find the fallback endpoint specified by route values: " +
"{ " + string.Join(", ", dynamicValues.Select(kvp => $"{kvp.Key}: {kvp.Value}")) + " }.");
}
else if (endpoints.Count == 0)
{
candidates.ReplaceEndpoint(i, null, null);
continue;
}
// We need to provide the route values associated with this endpoint, so that features
// like URL generation work.
var values = new RouteValueDictionary(dynamicValues);
// Include values that were matched by the fallback route.
if (originalValues != null)
{
foreach (var kvp in originalValues)
{
values.TryAdd(kvp.Key, kvp.Value);
}
}
if (transformer != null)
{
endpoints = await transformer.FilterAsync(httpContext, values, endpoints);
if (endpoints.Count == 0)
{
candidates.ReplaceEndpoint(i, null, null);
continue;
}
}
// Update the route values
candidates.ReplaceEndpoint(i, endpoint, values);
var loadedEndpoints = new List <Endpoint>(endpoints);
for (var j = 0; j < loadedEndpoints.Count; j++)
{
var metadata = loadedEndpoints[j].Metadata;
var pageActionDescriptor = metadata.GetMetadata <PageActionDescriptor>();
CompiledPageActionDescriptor compiled;
if (_loader is DefaultPageLoader defaultPageLoader)
{
compiled = await defaultPageLoader.LoadAsync(pageActionDescriptor, endpoint.Metadata);
}
else
{
compiled = await _loader.LoadAsync(pageActionDescriptor);
}
loadedEndpoints[j] = compiled.Endpoint;
}
// Expand the list of endpoints
candidates.ExpandEndpoint(i, loadedEndpoints, _comparer);
}
}