crul

An HTTP client, taking inspiration from Rubyland's faraday.

Installation

CRAN version

install.packages("crul")

Dev version

install.packages("devtools")
devtools::install_github("ropensci/crul")

library("crul")

the client

HttpClient is where to start

(x <- HttpClient$new(
  url = "https://httpbin.org",
  opts = list(
    timeout = 1
  ),
  headers = list(
    a = "hello world"
  )
))
#> <crul connection> 
#>   url: https://httpbin.org
#>   options: 
#>     timeout: 1
#>   headers: 
#>     a: hello world

Makes a R6 class, that has all the bits and bobs you'd expect for doing HTTP requests. When it prints, it gives any defaults you've set. As you update the object you can see what's been set

x$opts
#> $timeout
#> [1] 1

x$headers
#> $a
#> [1] "hello world"

You can also pass in curl options when you make HTTP requests, see below for examples.

do some http

The client object created above has http methods that you can call, and pass paths to, as well as query parameters, body values, and any other curl options.

Here, we'll do a GET request on the route /get on our base url https://httpbin.org (the full url is then https://httpbin.org/get)

res <- x$get("get")

The response from a http request is another R6 class HttpResponse, which has slots for the outputs of the request, and some functions to deal with the response:

Status code

res$status_code
#> [1] 200

Status information

res$status_http()
#> <Status code: 200>
#>   Message: OK
#>   Explanation: Request fulfilled, document follows

The content

res$content
#>   [1] 7b 0a 20 20 22 61 72 67 73 22 3a 20 7b 7d 2c 20 0a 20 20 22 68 65 61
#>  [24] 64 65 72 73 22 3a 20 7b 0a 20 20 20 20 22 41 22 3a 20 22 68 65 6c 6c
#>  [47] 6f 20 77 6f 72 6c 64 22 2c 20 0a 20 20 20 20 22 41 63 63 65 70 74 22
#>  [70] 3a 20 22 2a 2f 2a 22 2c 20 0a 20 20 20 20 22 41 63 63 65 70 74 2d 45
#>  [93] 6e 63 6f 64 69 6e 67 22 3a 20 22 67 7a 69 70 2c 20 64 65 66 6c 61 74
#> [116] 65 22 2c 20 0a 20 20 20 20 22 48 6f 73 74 22 3a 20 22 68 74 74 70 62
#> [139] 69 6e 2e 6f 72 67 22 2c 20 0a 20 20 20 20 22 55 73 65 72 2d 41 67 65
#> [162] 6e 74 22 3a 20 22 6c 69 62 63 75 72 6c 2f 37 2e 35 31 2e 30 20 72 2d
#> [185] 63 75 72 6c 2f 32 2e 33 20 63 72 75 6c 2f 30 2e 32 2e 30 22 0a 20 20
#> [208] 7d 2c 20 0a 20 20 22 6f 72 69 67 69 6e 22 3a 20 22 37 31 2e 36 33 2e
#> [231] 32 32 33 2e 31 31 33 22 2c 20 0a 20 20 22 75 72 6c 22 3a 20 22 68 74
#> [254] 74 70 73 3a 2f 2f 68 74 74 70 62 69 6e 2e 6f 72 67 2f 67 65 74 22 0a
#> [277] 7d 0a

HTTP method

res$method
#> [1] "get"

Request headers

res$request_headers
#> $useragent
#> [1] "libcurl/7.51.0 r-curl/2.3 crul/0.2.0"
#> 
#> $a
#> [1] "hello world"

Response headers

res$response_headers
#> $status
#> [1] "HTTP/1.1 200 OK"
#> 
#> $server
#> [1] "nginx"
#> 
#> $date
#> [1] "Tue, 03 Jan 2017 05:51:33 GMT"
#> 
#> $`content-type`
#> [1] "application/json"
#> 
#> $`content-length`
#> [1] "278"
#> 
#> $connection
#> [1] "keep-alive"
#> 
#> $`access-control-allow-origin`
#> [1] "*"
#> 
#> $`access-control-allow-credentials`
#> [1] "true"

And you can parse the content with parse()

res$parse()
#> No encoding supplied: defaulting to UTF-8.
#> [1] "{\n  \"args\": {}, \n  \"headers\": {\n    \"A\": \"hello world\", \n    \"Accept\": \"*/*\", \n    \"Accept-Encoding\": \"gzip, deflate\", \n    \"Host\": \"httpbin.org\", \n    \"User-Agent\": \"libcurl/7.51.0 r-curl/2.3 crul/0.2.0\"\n  }, \n  \"origin\": \"71.63.223.113\", \n  \"url\": \"https://httpbin.org/get\"\n}\n"
jsonlite::fromJSON(res$parse())
#> No encoding supplied: defaulting to UTF-8.
#> $args
#> named list()
#> 
#> $headers
#> $headers$A
#> [1] "hello world"
#> 
#> $headers$Accept
#> [1] "*/*"
#> 
#> $headers$`Accept-Encoding`
#> [1] "gzip, deflate"
#> 
#> $headers$Host
#> [1] "httpbin.org"
#> 
#> $headers$`User-Agent`
#> [1] "libcurl/7.51.0 r-curl/2.3 crul/0.2.0"
#> 
#> 
#> $origin
#> [1] "71.63.223.113"
#> 
#> $url
#> [1] "https://httpbin.org/get"

curl options

res <- HttpClient$new(url = "http://api.gbif.org/v1/occurrence/search")
res$get(query = list(limit = 100), timeout_ms = 100)
#> Error in curl::curl_fetch_memory(x$url$url, handle = x$url$handle) : 
#>   Timeout was reached

TO DO

Add integration for:

• webmockr
• vcr

for flexible and easy HTTP request caching

Meta

• Please report any issues or bugs.
• License: MIT
• Get citation information for crul in R doing citation(package = 'crul')
• Please note that this project is released with a Contributor Code of Conduct.

By participating in this project you agree to abide by its terms.