'Need an example on how to get preferred language from Accept-Language request header

I need a code example or library which would parse Accept-Language header and return me preferred language. RFC2616 states that:

The Accept-Language request-header field is similar to Accept, but restricts the set of natural languages that are preferred as a response to the request. Language tags are defined in section 3.10.

   Accept-Language = "Accept-Language" ":"
                     1#( language-range [ ";" "q" "=" qvalue ] )
   language-range  = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" )

Each language-range MAY be given an associated quality value which represents an estimate of the user's preference for the languages specified by that range. The quality value defaults to "q=1".

Further reading shows that there are too many "optional", "should", "may" and other turns of speech that prevent me from reinventing the wheel - all I want to know is what language user prefers, any browser answers this question billion times a day.

Any code snippet in any language (except Lisp and Assembler please) would be helpful.

Many thanks in advance!

c++sharpjavaphp.net


Solution 1:[1]

Solution:

namespace ConsoleApplication
{
    using System;
    using System.Linq;
    using System.Net.Http.Headers;

    class Program
    {
        static void Main(string[] args)
        {
            string header = "en-ca,en;q=0.8,en-us;q=0.6,de-de;q=0.4,de;q=0.2";
            var languages = header.Split(',')
                .Select(StringWithQualityHeaderValue.Parse)
                .OrderByDescending(s => s.Quality.GetValueOrDefault(1));
        }
    }
}

Result:

enter image description here

Solution 2:[2]

Update for ASP.NET Core:

Microsoft has that built in by now. Use the AcceptLanguageHeaderRequestCultureProvider:

IApplicationBuilder builder = ...;
builder.UseRequestLocalization(options => options
  .AddInitialRequestCultureProvider(new AcceptLanguageHeaderRequestCultureProvider()));

you can then get the IRequestCultureFeature through the context:

// probably injected through your DI container
IHttpContextAccessor _accessor = ...;
await _accessor.HttpContext.Features
  .Get<IRequestCultureFeature>().Provider
  .DetermineProviderCultureResult(_accessor.HttpContext);

that returns a ProviderCultureResult?, you can then read the cultures (in form of IList<StringSegment>) from that.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 weston
Solution 2 Mafii

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