PlugBest parses HTTP “Accept-*” headers and returns the best match based on a list of values.

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  • Updated at: 2020-03-05 17:52:01



PlugBest parses HTTP Accept-* headers and returns the best match based on a list of values.


Add plug_best to the deps function in your project's mix.exs file:

defp deps do
    {:plug_best, "~> 0.3"}

Then run mix do deps.get, deps.compile inside your project's directory.


PlugBest currently provides eight methods:

  • best_language/2
  • best_language_or_first/2
  • best_charset/2
  • best_charset_or_first/2
  • best_encoding/2
  • best_encoding_or_first/2
  • best_type/2
  • best_type_or_first/2

To find out which language is the best one to use among a list of supported languages:

conn |> Plug.Conn.get_req_header("accept-language")
# => ["fr-CA,fr;q=0.8,en;q=0.6,en-US;q=0.4"]

conn |> PlugBest.best_language(["en", "fr"])
# => {"fr-CA", "fr", 1.0}

If no values in the header is support, PlugBest will return the first nil. However, you can use the _or_first suffix to make it return the first value in those cases.

conn |> Plug.Conn.get_req_header("accept-language")
# => ["fr-CA,fr;q=0.8,en;q=0.6,en-US;q=0.4"]

conn |> PlugBest.best_language(["es", "ru"])
# => nil

conn |> PlugBest.best_language_or_first(["es", "ru"])
# => {"es", "es", 0.0}


PlugBest is © 2016-2017 Rémi Prévost and may be freely distributed under the MIT license. See the file for more information.