/// <summary>
/// Initializes a new instance of the <see cref="ResponseMediaTypeMatch"/> class.
/// </summary>
/// <param name="mediaTypeMatch">The <see cref="MediaTypeMatch"/> containing the media type and its quality factor.</param>
/// <param name="result">The kind of match.</param>
public ResponseMediaTypeMatch(MediaTypeMatch mediaTypeMatch, ResponseFormatterSelectionResult result)
{
Contract.Assert(mediaTypeMatch != null, "mediaTypeMatch cannot be null.");
Contract.Assert(Enum.IsDefined(typeof(ResponseFormatterSelectionResult), result), "result must be valid ResponseFormatterSelectionResult.");
ResponseFormatterSelectionResult = result;
MediaTypeMatch = mediaTypeMatch;
}
/// <summary>
/// Initializes a new instance of the <see cref="ResponseMediaTypeMatch"/> class.
/// </summary>
/// <param name="mediaTypeMatch">The <see cref="MediaTypeMatch"/> containing the media type and its quality factor.</param>
/// <param name="result">The kind of match.</param>
public ResponseMediaTypeMatch(MediaTypeMatch mediaTypeMatch, ResponseFormatterSelectionResult result)
{
Contract.Assert(mediaTypeMatch != null, "mediaTypeMatch cannot be null.");
Contract.Assert(Enum.IsDefined(typeof(ResponseFormatterSelectionResult), result), "result must be valid ResponseFormatterSelectionResult.");
ResponseFormatterSelectionResult = result;
MediaTypeMatch = mediaTypeMatch;
}
private static MediaTypeFormatter RunNegotiation(Type type, HttpRequestMessage request, IEnumerable <MediaTypeFormatter> formatters, out MediaTypeHeaderValue mediaType)
{
// Asking to serialize a response. This is the nominal code path.
// We ask all formatters for their best kind of match, and then we
// choose the best among those.
MediaTypeFormatter formatterMatchOnType = null;
ResponseMediaTypeMatch mediaTypeMatchOnType = null;
MediaTypeFormatter formatterMatchOnAcceptHeader = null;
ResponseMediaTypeMatch mediaTypeMatchOnAcceptHeader = null;
MediaTypeFormatter formatterMatchWithMapping = null;
ResponseMediaTypeMatch mediaTypeMatchWithMapping = null;
MediaTypeFormatter formatterMatchOnRequestContentType = null;
ResponseMediaTypeMatch mediaTypeMatchOnRequestContentType = null;
foreach (MediaTypeFormatter formatter in formatters)
{
ResponseMediaTypeMatch match = formatter.SelectResponseMediaType(type, request);
if (match == null)
{
// Null signifies no match
continue;
}
ResponseFormatterSelectionResult matchResult = match.ResponseFormatterSelectionResult;
switch (matchResult)
{
case ResponseFormatterSelectionResult.MatchOnCanWriteType:
// First match by type trumps all other type matches
if (formatterMatchOnType == null)
{
formatterMatchOnType = formatter;
mediaTypeMatchOnType = match;
}
break;
case ResponseFormatterSelectionResult.MatchOnResponseContentType:
// Match on response content trumps all other choices
mediaType = match.MediaTypeMatch.MediaType;
return(formatter);
case ResponseFormatterSelectionResult.MatchOnRequestAcceptHeader:
// Matches on accept headers must choose the highest quality match
double thisQuality = match.MediaTypeMatch.Quality;
if (formatterMatchOnAcceptHeader != null)
{
double bestQualitySeen = mediaTypeMatchOnAcceptHeader.MediaTypeMatch.Quality;
if (thisQuality <= bestQualitySeen)
{
continue;
}
}
formatterMatchOnAcceptHeader = formatter;
mediaTypeMatchOnAcceptHeader = match;
break;
case ResponseFormatterSelectionResult.MatchOnRequestWithMediaTypeMapping:
// Matches on accept headers using mappings must choose the highest quality match
double thisMappingQuality = match.MediaTypeMatch.Quality;
if (mediaTypeMatchWithMapping != null)
{
double bestMappingQualitySeen = mediaTypeMatchWithMapping.MediaTypeMatch.Quality;
if (thisMappingQuality <= bestMappingQualitySeen)
{
continue;
}
}
formatterMatchWithMapping = formatter;
mediaTypeMatchWithMapping = match;
break;
case ResponseFormatterSelectionResult.MatchOnRequestContentType:
// First match on request content type trumps other request content matches
if (formatterMatchOnRequestContentType == null)
{
formatterMatchOnRequestContentType = formatter;
mediaTypeMatchOnRequestContentType = match;
}
break;
}
}
// If we received matches based on both supported media types and from media type mappings,
// we want to give precedence to the media type mappings, but only if their quality is >= that of the supported media type.
// We do this because media type mappings are the user's extensibility point and must take precedence over normal
// supported media types in the case of a tie. The 99% case is where both have quality 1.0.
if (mediaTypeMatchWithMapping != null && mediaTypeMatchOnAcceptHeader != null)
{
if (mediaTypeMatchOnAcceptHeader.MediaTypeMatch.Quality > mediaTypeMatchWithMapping.MediaTypeMatch.Quality)
{
formatterMatchWithMapping = null;
}
}
// now select the formatter and media type
// A MediaTypeMapping is highest precedence -- it is an extensibility point
// allowing the user to override normal accept header matching
if (formatterMatchWithMapping != null)
{
mediaType = mediaTypeMatchWithMapping.MediaTypeMatch.MediaType;
return(formatterMatchWithMapping);
}
else if (formatterMatchOnAcceptHeader != null)
{
mediaType = mediaTypeMatchOnAcceptHeader.MediaTypeMatch.MediaType;
return(formatterMatchOnAcceptHeader);
}
else if (formatterMatchOnRequestContentType != null)
{
mediaType = mediaTypeMatchOnRequestContentType.MediaTypeMatch.MediaType;
return(formatterMatchOnRequestContentType);
}
else if (formatterMatchOnType != null)
{
mediaType = mediaTypeMatchOnType.MediaTypeMatch.MediaType;
return(formatterMatchOnType);
}
mediaType = null;
return(null);
}