cowboy_req:parse_qs(3)

Name

cowboy_req:parse_qs - Parse the query string

Description

parse_qs(Req :: cowboy_req:req()) -> parse_qs(Req, #{})
parse_qs(Req :: cowboy_req:req(), Opts)
    -> [{Key :: binary(), Value :: binary() | true}]

Opts :: #{max_keys => non_neg_integer()}

Parse the query string as a list of key/value pairs.

Arguments

Req

The Req object.

Opts

The max_keys option limits the maximum number of keys in the query string. It defaults to 100.

Return value

The parsed query string is returned as a list of key/value pairs. The key is a binary string. The value is either a binary string, or the atom true. Both key and value are case sensitive.

The atom true is returned when a key is present in the query string without a value. For example, in the following URIs the key <<"edit">> will always have the value true:

• /posts/42?edit
• /posts/42?edit&exclusive=1
• /posts/42?exclusive=1&edit
• /posts/42?exclusive=1&edit&from=web

Changelog

• 2.17: Function parse_qs/2 introduced with a max_keys option.
• 2.0: The parsed value is not longer cached in the Req object.
• 2.0: Only the parsed query string is returned, it is no longer wrapped in a tuple.
• 2.0: Function introduced. Replaces qs_val/1 and qs_vals/1.

Examples

ParsedQs = cowboy_req:parse_qs(Req),
AtomsQs = [{binary_to_existing_atom(K, latin1), V}
    || {K, V} <- ParsedQs].

See also

cowboy_req(3), cowboy_req:qs(3), cowboy_req:match_qs(3)