/// <summary>Gets the best encoding available for the specified charset request.</summary>
/// <param name="acceptableCharsets">
/// The Accept-Charset header value (eg: "iso-8859-5, unicode-1-1;q=0.8").
/// </param>
/// <param name="mediaType">The media type used to compute the default encoding for the payload.</param>
/// <param name="utf8Encoding">The encoding to use for UTF-8 charsets; we use the one without the BOM.</param>
/// <param name="defaultEncoding">The encoding to use if no encoding could be computed from the <paramref name="acceptableCharsets"/> or <paramref name="mediaType"/>.</param>
/// <returns>An Encoding object appropriate to the specifed charset request.</returns>
internal static Encoding EncodingFromAcceptableCharsets(string acceptableCharsets, ODataMediaType mediaType, Encoding utf8Encoding, Encoding defaultEncoding)
{
Debug.Assert(mediaType != null, "mediaType != null");
// Determines the appropriate encoding mapping according to
// RFC 2616.14.2 (http://tools.ietf.org/html/rfc2616#section-14.2).
Encoding result = null;
if (!string.IsNullOrEmpty(acceptableCharsets))
{
// PERF: in the future if we find that computing the encoding from the accept charsets is
// too expensive we could introduce a cache of original strings to resolved encoding.
CharsetPart[] parts = new List <CharsetPart>(AcceptCharsetParts(acceptableCharsets)).ToArray();
// NOTE: List<T>.Sort uses an unstable sort algorithm; if charsets have the same quality value
// we want to pick the first one specified so we need a stable sort.
KeyValuePair <int, CharsetPart>[] sortedParts = parts.StableSort(delegate(CharsetPart x, CharsetPart y)
{
return(y.Quality - x.Quality);
});
foreach (KeyValuePair <int, CharsetPart> sortedPart in sortedParts)
{
CharsetPart part = sortedPart.Value;
if (part.Quality > 0)
{
// When UTF-8 is specified, select the version that doesn't use the BOM.
if (String.Compare("utf-8", part.Charset, StringComparison.OrdinalIgnoreCase) == 0)
{
result = utf8Encoding;
break;
}
else
{
result = GetEncodingFromCharsetName(part.Charset);
if (result != null)
{
break;
}
// If the charset is not supported it is ignored so other possible charsets are evaluated.
}
}
}
}
// No Charset was specifed, or if charsets were specified, no valid charset was found.
// Returning a different charset is also valid. Get the default encoding for the media type.
if (result == null)
{
result = mediaType.SelectEncoding();
if (result == null)
{
return(defaultEncoding);
}
}
return(result);
}
/// <summary>
/// Given the Accept and the Accept-Charset headers of the request message computes the media type, encoding and <see cref="ODataFormat"/>
/// to be used for the response message.
/// </summary>
/// <param name="settings">The message writer settings to use for serializing the response payload.</param>
/// <param name="payloadKind">The kind of payload to be serialized as part of the response message.</param>
/// <param name="mediaTypeResolver">The media type resolver to use when interpreting the content type.</param>
/// <param name="mediaType">The media type to be used in the response message.</param>
/// <param name="encoding">The encoding to be used in the response message.</param>
/// <returns>The <see cref="ODataFormat"/> used when serializing the response.</returns>
internal static ODataFormat GetContentTypeFromSettings(
ODataMessageWriterSettings settings,
ODataPayloadKind payloadKind,
ODataMediaTypeResolver mediaTypeResolver,
out ODataMediaType mediaType,
out Encoding encoding)
{
Debug.Assert(settings != null, "settings != null");
// compute format, media type and encoding
ODataFormat format;
// get the supported and default media types for the specified payload kind
IList <ODataMediaTypeFormat> supportedMediaTypes = mediaTypeResolver.GetMediaTypeFormats(payloadKind).ToList();
if (supportedMediaTypes == null || supportedMediaTypes.Count == 0)
{
throw new ODataContentTypeException(Strings.MediaTypeUtils_DidNotFindMatchingMediaType(null, settings.AcceptableMediaTypes));
}
if (settings.UseFormat == true)
{
Debug.Assert(settings.AcceptableMediaTypes == null, "settings.AcceptableMediaTypes == null");
Debug.Assert(settings.AcceptableCharsets == null, "settings.AcceptableCharsets == null");
mediaType = GetDefaultMediaType(supportedMediaTypes, settings.Format, out format);
// NOTE the default media types don't have any parameters (in particular no 'charset' parameters)
encoding = mediaType.SelectEncoding();
}
else
{
// parse the accept header into its parts
IList <KeyValuePair <ODataMediaType, string> > specifiedTypes = HttpUtils.MediaTypesFromString(settings.AcceptableMediaTypes);
// Starting in V3 we replace all occurrences of application/json with application/json;odata.metadata=minimal
// before handing the acceptable media types to the conneg code. This is necessary because for an accept
// header 'application/json, we want to the result to be 'application/json;odata.metadata=minimal'
ConvertApplicationJsonInAcceptableMediaTypes(specifiedTypes);
ODataMediaTypeFormat selectedMediaTypeWithFormat;
string specifiedCharset = null;
if (specifiedTypes == null || specifiedTypes.Count == 0)
{
selectedMediaTypeWithFormat = supportedMediaTypes[0];
}
else
{
// match the specified media types against the supported/default ones and get the format
MediaTypeMatchInfo matchInfo = MatchMediaTypes(specifiedTypes.Select(kvp => kvp.Key), supportedMediaTypes.Select(smt => smt.MediaType).ToArray());
if (matchInfo == null)
{
// We're calling the ToArray here since not all platforms support the string.Join which takes IEnumerable.
string supportedTypesAsString = String.Join(", ", supportedMediaTypes.Select(mt => mt.MediaType.ToText()).ToArray());
throw new ODataContentTypeException(Strings.MediaTypeUtils_DidNotFindMatchingMediaType(supportedTypesAsString, settings.AcceptableMediaTypes));
}
selectedMediaTypeWithFormat = supportedMediaTypes[matchInfo.TargetTypeIndex];
specifiedCharset = specifiedTypes[matchInfo.SourceTypeIndex].Value;
}
format = selectedMediaTypeWithFormat.Format;
mediaType = selectedMediaTypeWithFormat.MediaType;
// If a charset was specified with the accept header, consider it for the encoding
string acceptableCharsets = settings.AcceptableCharsets;
if (specifiedCharset != null)
{
acceptableCharsets = acceptableCharsets == null ? specifiedCharset : specifiedCharset + "," + acceptableCharsets;
}
encoding = GetEncoding(acceptableCharsets, payloadKind, mediaType, /*useDefaultEncoding*/ true);
}
return(format);
}