header(Name, Req) -> header(Name, Req, undefined) header(Name, Req, Default) -> binary() | Default Name :: binary() %% lowercase; case insensitive Req :: cowboy_req:req() Default :: any()
cowboy_req:header - HTTP header
header(Name, Req) -> header(Name, Req, undefined) header(Name, Req, Default) -> binary() | Default Name :: binary() %% lowercase; case insensitive Req :: cowboy_req:req() Default :: any()
Return the value for the given HTTP header.
The header name must be given as a lowercase binary string. While header names are case insensitive, Cowboy requires them to be given as lowercase to function properly.
Headers can also be obtained using pattern matching:
#{headers := #{Name := Value}} = Req.Note that this snippet will crash if the header is missing.
Desired HTTP header name as a lowercase binary string.
The Req object.
Default value returned when the header is missing.
The header value is returned as a binary string. When the header is missing, the default argument is returned.
2.0: Only the header value is returned, it is no longer wrapped in a tuple.
1.0: Function introduced.
Accept = cowboy_req:header(<<"accept">>, Req).
Length = cowboy_req:header(<<"content-length">>, Req, <<"0">>).