This function generate S3 condition objects which are passed to stop or warning to generate classes warnings and error. These can be used in conjunction with tryCatch to respond differently to different type of failure.

http_condition(x, type, task = NULL, call = sys.call(-1))

Arguments

x

a response, or numeric http code (or other object with status_code method)

type

type of condition to generate. Must be one of error, warning or message.

task

The text of the message: either NULL or a character vector. If non-NULL, the error message will finish with "Failed to task".

call

The call stored in the condition object.

Value

An S3 object that inherits from (e.g.) condition, type, http_error, http_400 and http_404.

See also

http://adv-r.had.co.nz/Exceptions-Debugging.html#condition-handling for more details about R's condition handling model

Examples

# You can use tryCatch to take different actions based on the type # of error. Note that tryCatch will call the first handler that # matches any classes of the condition, not the best matching, so # always list handlers from most specific to least specific f <- function(url) { tryCatch(stop_for_status(GET(url)), http_404 = function(c) "That url doesn't exist", http_403 = function(c) "You need to authenticate!", http_400 = function(c) "You made a mistake!", http_500 = function(c) "The server screwed up" ) } f("http://httpbin.org/status/404")
#> [1] "That url doesn't exist"
f("http://httpbin.org/status/403")
#> [1] "You need to authenticate!"
f("http://httpbin.org/status/505")
#> [1] "The server screwed up"