static HttpContextExtensions()
{
GetRequestUserLanguagesImplementation = (context) =>
{
return(LanguageItem.ParseHttpLanguageHeader(context.Request.Headers["Accept-Language"]));
// NB: originally we passed LocalizedApplication.Current.DefaultLanguageTag
// here as the second parameter i.e. to specify the PAL. However, this was
// found to be incorrect when operating i18n with EarlyUrlLocalization disabled,
// as SetPrincipalAppLanguageForRequest was not being called, that normally
// overwriting the PAL set erroneously here.
};
}
public static void SetPrincipalAppLanguageForRequest(this HttpContextBase context, ILanguageTag pal, bool updateThreadCulture = true)
{
// The PAL is stored as the first item in the UserLanguages array (with Quality set to 2).
//
LanguageItem[] UserLanguages = GetRequestUserLanguages(context);
UserLanguages[0] = new LanguageItem(pal, LanguageItem.PalQualitySetting, 0);
// Run through any handlers installed for this event.
if (LocalizedApplication.Current.SetPrincipalAppLanguageForRequestHandlers != null)
{
foreach (LocalizedApplication.SetLanguageHandler handler in LocalizedApplication.Current.SetPrincipalAppLanguageForRequestHandlers.GetInvocationList())
{
handler(context, pal);
}
}
}
public static LanguageItem[] GetRequestUserLanguages(this HttpContextBase context)
{
// Determine UserLanguages.
// This value is created afresh first time this method is called per request,
// and cached for the request's remaining calls to this method.
LanguageItem[] UserLanguages = context.Items["i18n.UserLanguages"] as LanguageItem[];
if (UserLanguages == null)
{
// Construct UserLanguages list and cache it for the rest of the request.
context.Items["i18n.UserLanguages"]
= UserLanguages
= LanguageItem.ParseHttpLanguageHeader(
context.Request.Headers["Accept-Language"]);
// NB: originally we passed LocalizedApplication.Current.DefaultLanguageTag
// here as the second parameter i.e. to specify the PAL. However, this was
// found to be incorrect when operating i18n with EarlyUrlLocalization disabled,
// as SetPrincipalAppLanguageForRequest was not being called, that normally
// overwriting the PAL set erroneously here.
}
return(UserLanguages);
}
/// <summary>
/// Attempts to match the passed language with an AppLanguage.
/// </summary>
/// <param name="langtag">The subject language to match, typically a UserLanguage.</param>
/// <param name="maxPasses">
/// 0 - allow exact match only
/// 1 - allow exact match or default-region match only
/// 2 - allow exact match or default-region match or script match only
/// 3 - allow exact match or default-region match or script match or language match only
/// 4 - allow exact match or default-region match or script or language match only, or failing return the default language.
/// -1 to set to most tolerant (i.e. 4).
/// </param>
/// <returns>
/// A language tag identifying an AppLanguage that will be the same as, or related langtag.
/// </returns>
public static LanguageTag GetMatchingAppLanguage(string langtag, int maxPasses = -1)
{
return(GetMatchingAppLanguage(LanguageItem.ParseHttpLanguageHeader(langtag), maxPasses));
}
/// <summary>
/// Helper for translating the passed string entity which may contain zero or more fully-formed nugget,
/// which may be called when an HttpContext is not available e.g. in background jobs.
/// </summary>
/// <remarks>
/// When translating entities when handling HTTP requests, the language to use is selected from the current UserLanguages value
/// which is derived from the HttpContext (that is, the request headers). In a background job, however,
/// we don't normally have an HttpContext. With this method, however, you can save the UserLanguages
/// obtained from <see cref="i18n.HttpContextExtensions.ParseAndTranslate(System.Web.HttpContextBase, string)"/> when it is available,
/// i.e. prior to scheduling the background job, and pass it through to the job and then on to this method.
/// Note that the UserLanguages array value can be persisted as a string using the <see cref="LanguageItem.DehydrateLanguageItemsToString"/>
/// helper and converted back to an array using the <see cref="LanguageItem.HydrateLanguageItemsFromString"/> helper.
/// Note that this method does not support the localization of URLs embedded in the entity.
/// </remarks>
/// <param name="userLanguages">
/// A list of language preferences, sorted in order or preference (most preferred first)
/// in compact string form.
/// May be null/empty string in which case a a single-item language item array
/// representing a null PAL is returned.
/// Example values:
/// "fr-CA;q=1,fr;q=0.5"
/// "en-CA;q=2,de;q=0.5,en;q=1,fr-FR;q=0,ga;q=0.5"
/// "en-CA;q=1,de;q=0.5,en;q=1,fr-FR;q=0,ga;q=0.5"
/// "en-CA;q=1"
/// "?;q=2"
/// "?;q=2,de;q=0.5,en;q=1,fr-FR;q=0,ga;q=0.5"
/// ""
/// See <see cref="HttpContextExtensions.GetRequestUserLanguagesAsString"/>.
/// See <see cref="LanguageItem.DehydrateLanguageItemsToString"/>.
/// </param>
/// <param name="entity">
/// Entity to be processed. E.g HTTP response entity or Javascript file.
/// </param>
/// <returns>
/// Processed (and possibly modified) entity.
/// </returns>
/// <seealso cref="i18n.HttpContextExtensions.ParseAndTranslate(System.Web.HttpContextBase, string)"/>
public static string ParseAndTranslate(string entity, string userLanguages = null)
{
return(ParseAndTranslate(entity, LanguageItem.HydrateLanguageItemsFromString(userLanguages)));
}
/// <summary>
/// Returns a string representing a collection of languages supported by the user-agent, in descending order
/// of preference. The first item in the collection refers to any Principle Application Language (PAL)
/// for the request determined by EarlyUrlLocalization (which calls SetPrincipalAppLanguageForRequest),
/// or is null if EarlyUrlLocalization is disabled.
/// </summary>
/// <param name="context">Context of the current request.</param>
/// <returns>
/// Compact string representation of the language item array.
/// Example values:
/// "fr-CA;q=1,fr;q=0.5"
/// "en-CA;q=2,de;q=0.5,en;q=1,fr-FR;q=0,ga;q=0.5"
/// "en-CA;q=1,de;q=0.5,en;q=1,fr-FR;q=0,ga;q=0.5"
/// "en-CA;q=1"
/// "?;q=2"
/// "?;q=2,de;q=0.5,en;q=1,fr-FR;q=0,ga;q=0.5"
/// </returns>
/// <remarks>
/// This method is optimised such that the collection is built only once per request.
/// </remarks>
/// See <see cref="LanguageItem.ParseHttpLanguageHeader"/>.
/// See <see cref="LanguageItem.ParseHttpLanguageHeader"/>.
/// See <see cref="HttpContextExtensions.GetRequestUserLanguagesAsString"/>.
/// See <see cref="LanguageItem.DehydrateLanguageItemsToString"/>.
public static string GetRequestUserLanguagesAsString(this System.Web.HttpContextBase context)
{
return(LanguageItem.DehydrateLanguageItemsToString(GetRequestUserLanguages(context)));
}