req_has_cookie {scenes}

Switch Scenes on Cookies

Description

Create a scene_action specifying a cookie that must be present (or absent) and optionally a check function for that cookie.

Usage

req_has_cookie(cookie_name, validation_fn = NULL, ..., negate = FALSE)

Arguments

cookie_name

The cookie that must be present, as a length-1 character vector.

validation_fn

A function that takes the value of the cookie as the first parameter, and returns TRUE if the cookie is valid, and FALSE otherwise.

...

Additional parameters passed on to validation_fn.

negate

If TRUE, trigger the corresponding scene when this action is not matched.

Value

A scene_action object, to be used in set_scene().

Examples

# Specify an action to detect a cookie named "mycookie".
req_has_cookie("mycookie")

# Specify an action to detect the *lack* of a cookie named "mycookie".
req_has_cookie("mycookie", negate = TRUE)

# Specify an action to detect a cookie named "mycookie" that has 27
# characters.
req_has_cookie(
  cookie_name = "mycookie",
  validation_fn = function(cookie_value) {
    nchar(cookie_value == 27)
  }
)

# Specify an action to detect a cookie named "mycookie" that has N
# characters. This would make more sense in a case where validation_fn isn't
# an anonymous function.
req_has_cookie(
  cookie_name = "mycookie",
  validation_fn = function(cookie_value, N) {
    nchar(cookie_value) == N
  },
  N = 27
)