Erlang mime type

Question

How can i know mime type of file with Erlang?

Thank you.

Answer 1

If you want to know the mime type of a file based on its extension you can use the undocumented inets function httpd_conf:load_mime_types/1. This together with a mime.types file (there's one in one of the inets httpd examples in OTP) will give you a list of file extensions and their default associated mime types. The following code will give you the standard mime type for a given filename based on its extension:

mime_type(FileName) ->
    "." ++ Extension = filename:extension(FileName),
    MimeTypes = mime_types(),
    proplists:get_value(Extension, MimeTypes).

mime_types() ->
    MimeTypesFile = filename:join(code:lib_dir(inets), 
                                  "examples/server_root/conf/mime.types"),
    {ok, MimeTypes} = httpd_conf:load_mime_types(MimeTypesFile),
    MimeTypes.

You can now use mime_type/1 on a filename (e.g. example.pdf) and it will return you the default mime type if known (in this case "application/pdf") or undefined otherwise.

If you're going to do this operation repeatedly, it would be a good idea to cache the result of httpd_conf:load_mime_types/1 as the inets httpd server does, so that you avoid reading and parsing the mime types file all the time.