cowboy_req:parse_cookies(3)

Name

cowboy_req:parse_cookies - Parse cookie headers

Description

parse_cookies(Req) -> [{Name, Value}]

Name  :: binary() %% case sensitive
Value :: binary() %% case sensitive

Parse cookie headers.

Alias for cowboy_req:parse_header(<<"cookie">>, Req).

When the cookie header is missing or empty, [] is returned.

This function will crash on invalid cookie data. Because invalid cookies are fairly common when dealing with browsers (because of the string interface that the Javascript API provides), it is recommended to filter the cookie header value before attempting to parse it. This can be accomplished by calling the function cowboy_req:filter_cookies(3) first. This does not guarantee that parsing succeeds. If it still fails it is recommended to send an error response or redirect with instructions to delete the relevant cookies:

Req1 = cowboy_req:filter_cookies([session_id, token], Req0),
try cowboy_req:parse_cookies(Req1) of
    Cookies ->
        do_something(Req1, Cookies)
catch _:_ ->
    %% We can't parse the cookies we need, unset them
    %% otherwise the browser will continue sending them.
    Req2 = cowboy_req:set_resp_cookie(<<"session_id">>,
        <<>>, Req1, #{max_age => 0}),
    Req = cowboy_req:set_resp_cookie(<<"token">>,
        <<>>, Req2, #{max_age => 0}),
    cowboy_req:reply(500, Req)
end.

Arguments

Req

The Req object.

Return value

The cookies are returned as a list of key/values. Keys and values are case sensitive binary strings.

Changelog

• 2.0: Only the parsed header value is returned, it is no longer wrapped in a tuple.
• 2.0: Function introduced. Replaces cookie/2,3 and cookies/1.

Examples

Cookies = cowboy_req:parse_cookies(Req),
{_, Token} = lists:keyfind(<<"token">>, 1, Cookies).

See also

cowboy_req(3), cowboy_req:parse_header(3), cowboy_req:filter_cookies(3), cowboy_req:match_cookies(3)