Introduction to the fauxpas package

fauxpas does http errors!

HTTP error classes more in line with Ruby/Python/Etc. (psssttt: that is a good thing)
An error class for each HTTP status in case a user wants to be specific to an HTTP status code, and general purpose handlers for any error
Work with any of the major R http clients: crul, curl, httr (maybe RCurl later)
Provide flexiblity for what to do on an HTTP error, including custom functions and message templates

There are a lot of functions in this package. Don’t be scared away by that. There are a few major sets of functions that are easy to understand and use:

There’s a function http() that is a general purpose function that handles any HTTP status codes. There’s also a set of functions that follow the pattern http*() where * is a HTTP status code (e.g. http201()). You can use the general purpose function http() or the one specific to the status code you are interested in.
There’s a lower level R6 class Error that is wrapped by http() that like http() is a general purpose function that handles any HTTP status codes. There’s also a set of R6 classes that follow the pattern HTTP*() where * is a HTTP name (e.g. HTTPGatewayTimeout). You can use the general purpose class Error() or the one specific to the status you are interested in.

fauxpas uses httpcode under the hood - which holds all the info about HTTP status codes.

Install

CRAN version

install.packages("fauxpas")

Dev version

# install.packages("remotes")
remotes::install_github("sckott/fauxpas")

library("fauxpas")

Find classes for a HTTP status code

When using fauxpas in another package I personally like to use the HTTP* classes.

Since these are named with their HTTP reason (e.g. HTTPGatewayTimeout), it’s not super straightforward to find them with a status code, which is what one always has as a response from a server. A good way to find these is with a new function find_error_class(). Just pass the function a HTTP status code and it will find the matching class.

(x <- find_error_class(418))
#> <HTTPTeaPot> object generator
#>   Inherits from: <Error>
#>   Public:
#>     name: HTTPTeaPot
#>     status_code: 418
#>     mssg: 
#>     do_verbose: function (response, template = self$message_template_verbose) 
#>     clone: function (deep = FALSE) 
#>   Parent env: <environment: 0x135e88de0>
#>   Locked objects: TRUE
#>   Locked class: FALSE
#>   Portable: TRUE

Which returns the matching error class object, with which you can initialize a new object:

x$new()
#> <HTTPTeaPot>
#>   behavior: stop
#>   message_template: {{reason}} (HTTP {{status}})
#>   message_template_verbose: {{reason}} (HTTP {{status}}).\n - {{message}}

If you pass it a status code it doesn’t know about it errors

find_error_class(999)
#> Error in find_error_class(999) : no method found for 999

Use fauxpas with HTTP clients

crul

library("crul")
cli <- HttpClient$new("https://httpbin.org/status/414")
res <- cli$get()
http(res)
#> Error: Request-URI Too Long (HTTP 414).
http414(res)
#> Error: Request-URI Too Long (HTTP 414).

x <- HTTPRequestURITooLong$new()
x$do_verbose(res)
#> Error: Request-URI Too Long (HTTP 414).
#> - The server is refusing to service the request because the Request-URI is
#>    longer than the server is willing to interpret. This rare condition is only likely
#>    to occur when a client has improperly converted a POST request to a GET request
#>    with long query information, when the client has descended into a URI black hole
#>    of redirection (e.g., a redirected URI prefix that points to a suffix of itself),
#>    or when the server is under attack by a client attempting to exploit security
#>    holes present in some servers using fixed-length buffers for reading or
#>    manipulating the Request-URI.

curl

library("curl")
h <- curl::new_handle()
curl::handle_setopt(h)
resp <- curl::curl_fetch_memory("https://httpbin.org/status/404", h)
http(resp)
#> Error: Not Found (HTTP 404).
http404(resp)
#> Error: Not Found (HTTP 404).

x <- HTTPNotFound$new()
x$do_verbose(resp)
#> Error:  Not Found (HTTP 404).
#>  - The server has not found anything matching the Request-URI. No indication is
#> given of whether the condition is temporary or permanent. The 410 (Gone) status
#> code SHOULD be used if the server knows, through some internally configurable
#> mechanism, that an old resource is permanently unavailable and has no forwarding
#> address. #> This status code is commonly used when the server does not wish to
#> reveal exactly why the request has been refused, or when no other response is
#> applicable.

httr

library("httr")
res <- GET("https://httpbin.org/status/405")
http405(res)
#> Error: Method Not Allowed (HTTP 405).

x <- HTTPMethodNotAllowed$new()
x$do_verbose(res)
#> Error: Method Not Allowed (HTTP 405).
#>  - The method specified in the Request-Line is not allowed for the resource
#> identified by the Request-URI. The response MUST include an Allow header
#> containing a list of valid methods for the requested resource.