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While the http protocol is rather basic in essence, it can be a pain
to work with. reqres is here to soothe the pain somewhat by
providing two powerful classes for handling all parts of request and
response handling during a http exchange. This is not a web
server, instead it focuses on making life easier for developers of
web servers by extracting the complexity of cookies, headers, content
negotiation, and the likes into neat little classes. reqres
builds upon the rook
specifications and is thus well suited for httpuv-based
webservers.
reqres draws a lot of inspiration from express.js and the Request
and Response classes is aiming for feature parity with
those from express. The Request class provides automatic
parsing of the query string along with parsing of the body based on the
Content-Type header (with decompression if
Content-Encoding is provided). Further, it provides content
negotiation based on the Accept(-*) headers. The
Response class allows you to set headers and cookies
easily, assign arbitrary data for later use, and automatically format
the body based on content negotiation with the Request
object that it is responding to (again, it will compress automatically
if the Accept-Encoding header allows it). If any part of
the content negotiation fails the correct response status code will be
set, making the response ready to send.
reqres comes with a range of parsers and formatters
making it work out of the box with json, xml, html, csv, tab, multipart,
and www-form-urlencoded payloads. It is easy to either modify these or
provide your own parsers and formatters if needed - reqres
will take care of the content negotiation and simply call your custom
parser/formatter if chosen.
reqrescan be installed from CRAN with
install.packages('reqres') or the development version can
be installed from github:
# install.packages('devtools')
devtools::install_github('thomasp85/reqres')Below is a quick demo of some of the features in reqres.
It uses the fake_request() in fiery to mock a
rook request so it can be used without setting up a webserver:
library(reqres)
# We start by mocking our request
rook <- fiery::fake_request(
url = 'http://www.example.com/summary?id=2347&user=Thomas+Lin+Pedersen',
content = '{"name":["Thomas Lin Pedersen"],"age":[31],"homepage":["www.data-imaginist.com","www.github.com/thomasp85"]}',
headers = list(
Content_Type = 'application/json',
Accept = 'application/json, application/xml; q=0.5, text/*; q=0.3',
Accept_Encoding = 'gzip, br'
)
)
# A Request object can now be created
req <- Request$new(rook)
req
#> A HTTP request
#> ==============
#> Trusted: No
#> Method: get
#> URL: http://www.example.com:80/summary?id=2347&user=Thomas+Lin+Pedersen
# ... along with a response
res <- req$respond()
res
#> A HTTP response
#> ===============
#> Status: 404 - Not Found
#> Content type: text/plain
#>
#> In response to: http://www.example.com:80/summary?id=2347&user=Thomas+Lin+PedersenA lot of information is already available, such as the query and other parts of the url, but the body is not filled in automatically.
req$host
#> [1] "www.example.com:80"
req$query
#> $id
#> [1] 2347
#>
#> $user
#> [1] "Thomas Lin Pedersen"
req$body
#> NULLThe body can easily be parsed though, as long as a parser exists for the provided content type.
req$is('json')
#> [1] TRUE
req$parse(json = parse_json())
#> [1] TRUE
req$body
#> $name
#> [1] "Thomas Lin Pedersen"
#>
#> $age
#> [1] 31
#>
#> $homepage
#> [1] "www.data-imaginist.com" "www.github.com/thomasp85"Instead of inspecting it manually you can simply provide a range of parsers and let the object choose the correct one itself
req$set_body(NULL)
req$parse(
txt = parse_plain(),
html = parse_html(),
json = parse_json()
)
#> [1] TRUE
req$body
#> $name
#> [1] "Thomas Lin Pedersen"
#>
#> $age
#> [1] 31
#>
#> $homepage
#> [1] "www.data-imaginist.com" "www.github.com/thomasp85"In the case that none of the provided parsers fits the content type, the response will automatically get updated with the correct error code
req$set_body(NULL)
req$parse(txt = parse_plain())
#> [1] FALSE
res
#> A HTTP response
#> ===============
#> Status: 415 - Unsupported Media Type
#> Content type: text/plain
#>
#> In response to: http://www.example.com:80/summary?id=2347&user=Thomas+Lin+PedersenTo facilitate all this reqres comes with a mapping of
standard mime types to the provided parsers. This can simply be supplied
to the parse method
req$set_body(NULL)
req$parse(default_parsers)
#> [1] TRUE
req$body
#> $name
#> [1] "Thomas Lin Pedersen"
#>
#> $age
#> [1] 31
#>
#> $homepage
#> [1] "www.data-imaginist.com" "www.github.com/thomasp85"While the request is mainly intended to be read from, the response
should be written to. The Response class contains a slew of
methods to easily set headers, cookies, etc.
res$set_header('Date', to_http_date(Sys.time()))
res$get_header('Date')
#> [1] "Fri, 19 Aug 2022 12:12:12 GMT"
res$set_cookie('user', req$query$id, max_age = 9000L)
res$has_cookie('user')
#> [1] TRUEFurthermore, it contains its own data store where arbitrary information can be stored so as to pass it between middleware etc. This data will never be part of the actual response.
res$set_data('alphabet', letters)
res$get_data('alphabet')
#> [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s"
#> [20] "t" "u" "v" "w" "x" "y" "z"Files can be attached and marked for download, setting the relevant headers automatically
res$attach(system.file('NEWS.md', package = 'reqres'))
res$get_header('Content-Type')
#> [1] "text/markdown"
res$get_header('Content-Disposition')
#> [1] "attachment; filename=NEWS.md"Often we need to provide a payload in the form of a body. This can be any type of R object until the response is handed off to the server, where it should be either a string or a raw vector.
res$remove_header('Content-Disposition')
res$body <- head(mtcars)
res$body
#> mpg cyl disp hp drat wt qsec vs am gear carb
#> Mazda RX4 21.0 6 160 110 3.90 2.620 16.46 0 1 4 4
#> Mazda RX4 Wag 21.0 6 160 110 3.90 2.875 17.02 0 1 4 4
#> Datsun 710 22.8 4 108 93 3.85 2.320 18.61 1 1 4 1
#> Hornet 4 Drive 21.4 6 258 110 3.08 3.215 19.44 1 0 3 1
#> Hornet Sportabout 18.7 8 360 175 3.15 3.440 17.02 0 0 3 2
#> Valiant 18.1 6 225 105 2.76 3.460 20.22 1 0 3 1Based on the Accept header in the request it can be
formatted correctly thus making it ready to send back to the client. As
this request contains an Accept-Encoding header it will be
compressed as well.
res$format(json = format_json())
#> [1] TRUE
res$body
#> [1] 1f 8b 08 00 00 00 00 00 00 03 9d d2 41 4f 83 30 14 07 f0 af 42 de b9 69 da
#> [26] 47 29 a5 e7 1d bc 78 d1 44 4d 8c 31 dd 20 48 b2 01 16 36 a2 c6 ef 6e d9 a0
#> [51] 6c 63 4b d4 db 4b d3 f6 fd de bf 7d fe 82 4d 9d 83 46 4e 60 f5 b1 06 2d 09
#> [76] a4 45 53 83 e6 92 11 78 eb 0b ee 8a d4 9a 16 74 48 13 02 9d 2b 90 4a 24 f0
#> [101] de 64 ab 7e 23 15 ee d4 ae 01 ed 36 9a 8d 5b 21 90 67 c6 82 16 ee 52 63 97
#> [126] fb e2 d5 56 1d 68 b8 35 9f a9 09 ee 9e 04 7c 93 ff f6 56 71 e4 9b c7 94 e1
#> [151] df 9b 07 8f 26 3f 02 b8 2b 07 82 f0 04 a6 0e 84 24 9c 04 2a 1a 09 e1 34 be
#> [176] a2 92 1f 04 fc 9a 80 7b c1 c2 b4 cd b6 0c 62 ce 8e e7 a7 e2 3c 01 8c d4 85
#> [201] 04 7a 53 b7 af 90 4f 11 24 54 88 13 00 1b 01 e1 1c 70 53 d9 32 6b 03 11 2c
#> [226] 6c b1 cb 26 84 1b 23 1e 10 6a 44 84 fe 19 fa c0 47 04 8f 46 44 df f6 da 33
#> [251] cc 0d 78 6e b8 af 2b db 9a 65 b5 6d 4f 18 b3 df 80 18 0d 0c e6 19 48 63 e9
#> [276] 19 72 64 20 a3 88 bf 8e e2 c1 ac 0b 53 ba e6 2f 3f 40 6a d7 44 06 03 00 00
res$get_header('Content-Type')
#> [1] "application/json"
res$get_header('Content-Encoding')
#> [1] "gzip"The content negotiation understands wildcards as well
res$body <- head(mtcars)
req$get_header('Accept')
#> [1] "application/json" "application/xml; q=0.5" "text/*; q=0.3"
res$format(csv = format_table(sep = ','), compress = FALSE)
#> [1] TRUE
res$body
#> [1] "\"mpg\",\"cyl\",\"disp\",\"hp\",\"drat\",\"wt\",\"qsec\",\"vs\",\"am\",\"gear\",\"carb\"\n\"Mazda RX4\",21,6,160,110,3.9,2.62,16.46,0,1,4,4\n\"Mazda RX4 Wag\",21,6,160,110,3.9,2.875,17.02,0,1,4,4\n\"Datsun 710\",22.8,4,108,93,3.85,2.32,18.61,1,1,4,1\n\"Hornet 4 Drive\",21.4,6,258,110,3.08,3.215,19.44,1,0,3,1\n\"Hornet Sportabout\",18.7,8,360,175,3.15,3.44,17.02,0,0,3,2\n\"Valiant\",18.1,6,225,105,2.76,3.46,20.22,1,0,3,1"
res$get_header('Content-Type')
#> [1] "text/csv"A default formatter mapping exists in parallel to
default_parsers for the Request$format()
method.
res$body <- head(mtcars)
res$format(default_formatters, compress = FALSE)
#> [1] TRUE
res$body
#> [{"mpg":21,"cyl":6,"disp":160,"hp":110,"drat":3.9,"wt":2.62,"qsec":16.46,"vs":0,"am":1,"gear":4,"carb":4,"_row":"Mazda RX4"},{"mpg":21,"cyl":6,"disp":160,"hp":110,"drat":3.9,"wt":2.875,"qsec":17.02,"vs":0,"am":1,"gear":4,"carb":4,"_row":"Mazda RX4 Wag"},{"mpg":22.8,"cyl":4,"disp":108,"hp":93,"drat":3.85,"wt":2.32,"qsec":18.61,"vs":1,"am":1,"gear":4,"carb":1,"_row":"Datsun 710"},{"mpg":21.4,"cyl":6,"disp":258,"hp":110,"drat":3.08,"wt":3.215,"qsec":19.44,"vs":1,"am":0,"gear":3,"carb":1,"_row":"Hornet 4 Drive"},{"mpg":18.7,"cyl":8,"disp":360,"hp":175,"drat":3.15,"wt":3.44,"qsec":17.02,"vs":0,"am":0,"gear":3,"carb":2,"_row":"Hornet Sportabout"},{"mpg":18.1,"cyl":6,"disp":225,"hp":105,"drat":2.76,"wt":3.46,"qsec":20.22,"vs":1,"am":0,"gear":3,"carb":1,"_row":"Valiant"}]It is easy to define your own formatters and add them along the defaults
res$body <- head(mtcars)
res$format('text/yaml' = yaml::as.yaml, compress = FALSE)
#> [1] TRUE
res$body
#> [1] "mpg:\n- 21.0\n- 21.0\n- 22.8\n- 21.4\n- 18.7\n- 18.1\ncyl:\n- 6.0\n- 6.0\n- 4.0\n- 6.0\n- 8.0\n- 6.0\ndisp:\n- 160.0\n- 160.0\n- 108.0\n- 258.0\n- 360.0\n- 225.0\nhp:\n- 110.0\n- 110.0\n- 93.0\n- 110.0\n- 175.0\n- 105.0\ndrat:\n- 3.9\n- 3.9\n- 3.85\n- 3.08\n- 3.15\n- 2.76\nwt:\n- 2.62\n- 2.875\n- 2.32\n- 3.215\n- 3.44\n- 3.46\nqsec:\n- 16.46\n- 17.02\n- 18.61\n- 19.44\n- 17.02\n- 20.22\nvs:\n- 0.0\n- 0.0\n- 1.0\n- 1.0\n- 0.0\n- 1.0\nam:\n- 1.0\n- 1.0\n- 1.0\n- 0.0\n- 0.0\n- 0.0\ngear:\n- 4.0\n- 4.0\n- 4.0\n- 3.0\n- 3.0\n- 3.0\ncarb:\n- 4.0\n- 4.0\n- 1.0\n- 1.0\n- 2.0\n- 1.0\n"Please note that the ‘reqres’ project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.
These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
Health stats visible at Monitor.