High Level 'HTTP' Client.

request

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.

Philosophy

• The web is increasingly a JSON world, so we set content-type and accept headers to applications/json by default
• 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

devtools::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/')
#> URL: https://api.github.com/
api('http://api.gbif.org/v1')
#> URL: http://api.gbif.org/v1
api('api.gbif.org/v1')
#> URL: api.gbif.org/v1

Works with ports, full or partial

api('http://localhost:9200')
#> URL: http://localhost:9200
api('localhost:9200')
#> URL: http://localhost:9200
api(':9200')
#> URL: http://localhost:9200
api('9200')
#> URL: http://localhost:9200
api('9200/stuff')
#> URL: http://localhost: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()
#> $current_user_url
#> [1] "https://api.github.com/user"
#> 
#> $current_user_authorizations_html_url
#> [1] "https://github.com/settings/connections/applications{/client_id}"
#> 
#> $authorizations_url
#> [1] "https://api.github.com/authorizations"
#> 
#> $code_search_url
...

Or

api('https://api.github.com/') %>% http()
#> $current_user_url
#> [1] "https://api.github.com/user"
#> 
#> $current_user_authorizations_html_url
#> [1] "https://github.com/settings/connections/applications{/client_id}"
#> 
#> $authorizations_url
#> [1] "https://api.github.com/authorizations"
#> 
#> $code_search_url
...

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
#> <http request> 
#>   url: https://api.github.com/
#>   paths: 
#>   query: 
#>   body: 
#>   paging: 
#>   headers: 
#>   rate limit: 
#>   retry (n/delay (s)): /
#>   error handler: 
#>   config:

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
#> <http request> 
#>   url: https://api.github.com/
#>   paths: repos/ropensci/rgbif/issues
#>   query: 
#>   body: 
#>   paging: 
#>   headers: 
#>   rate limit: 
#>   retry (n/delay (s)): /
#>   error handler: 
#>   config:

Query

api("http://api.plos.org/search") %>%
  api_query(q = ecology, wt = json, fl = 'id,journal') %>%
  peep
#> <http request> 
#>   url: http://api.plos.org/search
#>   paths: 
#>   query: q=ecology, wt=json, fl=id,journal
#>   body: 
#>   paging: 
#>   headers: 
#>   rate limit: 
#>   retry (n/delay (s)): /
#>   error handler: 
#>   config:

ToDo

See the issues for discussion of these

• Paging
• Retry
• Rate limit

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