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= cowboy_req:binding(3)
== Name
cowboy_req:binding - Access a value bound from the route
== Description
[source,erlang]
----
binding(Name, Req) -> binding(Name, Req, undefined)
binding(Name, Req, Default) -> any() | Default
Name :: atom()
Req :: cowboy_req:req()
Default :: any()
----
Return the value for the given binding.
== Arguments
Name::
Desired binding name as an atom.
Req::
The Req object.
Default::
Default value returned when the binding is missing.
== Return value
By default the value is a case sensitive binary string, however
constraints may change the type of this value (for example
automatically converting numbers to integer).
== Changelog
* *2.0*: Only the value is returned, it is no longer wrapped in a tuple.
* *1.0*: Function introduced.
== Examples
.Get the username from the path
[source,erlang]
----
%% Route is "/users/:user"
Username = cowboy_req:binding(user, Req).
----
.Get the branch name, with a default
[source,erlang]
----
%% Route is "/log[/:branch]"
Branch = cowboy_req:binding(branch, Req, <<"master">>)
----
== See also
link:man:cowboy_req(3)[cowboy_req(3)],
link:man:cowboy_req:bindings(3)[cowboy_req:bindings(3)],
link:man:cowboy_req:host_info(3)[cowboy_req:host_info(3)],
link:man:cowboy_req:path_info(3)[cowboy_req:path_info(3)],
link:man:cowboy_router(3)[cowboy_router(3)]
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