request

hook_output <- knitr::knit_hooks$get("output")
knitr::knit_hooks$set(output = function(x, options) {
   lines <- options$output.lines
   if (is.null(lines)) {
     return(hook_output(x, options))  # pass to default hook
   }
   x <- unlist(strsplit(x, "\n"))
   more <- "..."
   if (length(lines) == 1) {        # first n lines
     if (length(x) > lines) {
       # truncate the output, but add ....
       x <- c(head(x, lines), more)
     }
   } else {
     x <- c(if (abs(lines[1])>1) more else NULL,
            x[lines],
            if (length(x)>lines[abs(length(lines))]) more else NULL
           )
   }
   # paste these lines together
   x <- paste(c(x, ""), collapse = "\n")
   hook_output(x, options)
 })

knitr::opts_chunk$set(
  warning = FALSE,
  message = FALSE,
  collapse = TRUE,
  comment = "#>"
)

request is DSL for http requests for R, and is inspired by the CLI tool httpie.

request is built on httr, though may allow using the R packages RCurl or curl as optional backends at some point.

I gave a poster at User2016, its in my talks repo

Philosophy

• The web is increasingly a JSON world, so we assume applications/json by default, but give back other types if not
• The workflow follows logically, or at least should, from, hey, I got this url, to i need to add some options, to execute request
• Whenever possible, we transform output to data.frame's - facilitating downstream manipulation via dplyr, etc.
• We do GET requests by default. Specify a different type if you don't want GET
• You can use non-standard evaluation to easily pass in query parameters without worrying about &'s, URL escaping, etc. (see api_query())
• Same for body params (see api_body())

All of the defaults just mentioned can be changed.

Auto execute http requests with pipes

When using pipes, we autodetect that a pipe is being used within the function calls, and automatically do the appropriate http request on the last piped function call. When you call a function without using pipes, you have to use the http() function explicitly to make the http request.

low level http

Low level access is available with http_client(), which returns an R6 class with various methods for inspecting http request results.

Peek at a request

The function peep() let's you peek at a request without performing the http request.

Install

From CRAN

install.packages("request")

Development version from GitHub

remotes::install_github("sckott/request")

library("request")

NSE and SE

NSE is supported

api('https://api.github.com/') %>%
  api_path(repos, ropensci, rgbif, issues)

as well as SE

api('https://api.github.com/') %>%
  api_path_('repos', 'ropensci', 'rgbif', 'issues')

Building API routes

Works with full or partial URLs

api('https://api.github.com/')
api('http://api.gbif.org/v1')
api('api.gbif.org/v1')

Works with ports, full or partial

api('http://localhost:9200')
api('localhost:9200')
api(':9200')
api('9200')
api('9200/stuff')

Make HTTP requests

The above examples with api() are not passed through a pipe, so only define a URL, but don't do an HTTP request. To make an HTTP request, you can either pipe a url or partial url to e.g., api(), or call http() at the end of a string of function calls:

'https://api.github.com/' %>% api()

Or

api('https://api.github.com/') %>% http()

http() is called at the end of a chain of piped commands, so no need to invoke it. However, you can if you like.

Templating

repo_info <- list(username = 'craigcitro', repo = 'r-travis')
api('https://api.github.com/') %>%
  api_template(template = 'repos/{{username}}/{{repo}}/issues', data = repo_info) %>%
  peep

Set paths

api_path() adds paths to the base URL (see api_query()) for query parameters

api('https://api.github.com/') %>%
  api_path(repos, ropensci, rgbif, issues) %>%
  peep

Query

api("http://api.plos.org/search") %>%
  api_query(q = ecology, wt = json, fl = 'id,journal') %>%
  peep

ToDo

See the issues for discussion of these

• Paging
• Retry
• Rate limit

Meta

• 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.