Simple HTTP and REST client for Crystal, inspired by the Ruby's RestClient gem.
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README.md

crest

Build Status GitHub release Commits Since Last Release Docs License

Simple HTTP and REST client for Crystal, inspired by the Ruby's RestClient gem.

Installation

Add this to your application's shard.yml:

dependencies:
  crest:
    github: mamantoha/crest

Usage

require "crest"

Basic usage:

Crest.get(
  "http://httpbin.org/get",
  params: {:lang => "en"}
)
# curl -L "http://httpbin.org/get?lang=en"

Crest.post(
  "http://httpbin.org/post",
  form: {:age => 27, :name => {:first => "Kurt", :last => "Cobain"}}
)
# curl -L --data "age=27&name[first]=Kurt&name[last]=Cobain" -X POST "http://httpbin.org/post"

Passing advanced options

Crest::Request accept next parameters:

Mandatory parameters:

  • :method - HTTP method (:get. :post, :put, :patch, :delete, :options)
  • :url - URL (e.g.: http://httpbin.org/ip)

Optional parameters:

  • :headers - a hash containing the request headers
  • :cookies - a hash containing the request cookies
  • :form - a hash containing form params
  • :params - a hash that represent query-string separated from the preceding part by a question mark (?) a sequence of attribute–value pairs separated by a delimiter (&)
  • :user and :password - for Basic Authentication
  • :p_addr, :p_port, :p_user, and :p_pass - specify a per-request proxy by passing these parameters
  • :max_redirects - maximum number of redirections (default to 10)
  • :logging - enable logging (default to false)
  • :logger - set logger (default to Crest::CommonLogger)
  • :handle_errors - error handling (default to true)
  • :http_client - instance of HTTP::Client

More detailed examples:

request = Crest::Request.new(:post,
  "http://httpbin.org/post",
  headers: {"Content-Type" => "application/json"},
  form: {:width => 640, "height" => "480"}
)
request.execute
# curl -L --data "width=640&height=480" --header "Content-Type: application/json" -X POST "http://httpbin.org/post"

Crest::Request.execute(:get,
  "http://httpbin.org/get",
  params: {:width => 640, "height" => "480"},
  headers: {"Content-Type" => "application/json"})
)
# curl -L --header "Content-Type: application/json" "http://httpbin.org/get?width=640&height=480"

Crest::Request.get(
  "http://httpbin.org/get",
  p_addr: "127.0.0.1",
  p_port: 3128,
  p_user: "admin",
  p_pass: "1234"
)
# curl -L --proxy http://127.0.0.1:3128 --proxy-user admin:1234 "http://httpbin.org/get"

A block can be passed to the Crest::Request instance.

This block will then be called with the Crest::Request.

request = Crest::Request.new(:get, "http://httpbin.org/headers") do |request|
  request.headers.add("foo", "bar")
end

request.execute
# curl -L --header "foo: bar" http://httpbin.org/headers

Access HTTP::Client

You can access HTTP::Client via the http_client instance method.

This is usually used to set additional options (e.g. read timeout, authorization header etc.)

client = HTTP::Client.new("http://httpbin.org")
client.read_timeout = 1.second

begin
  Crest::Request.new(:get,
    "http://httpbin.org/delay/10",
    http_client: client
  )
rescue IO::Timeout
  puts "Timeout!"
end

Multipart

Yeah, that's right! This does multipart sends for you!

file = File.open("#{__DIR__}/example.png")
Crest.post("http://httpbin.org/post", form: {:image => file})
file = File.open("#{__DIR__}/example.png")
resource = Crest::Resource.new("https://httpbin.org")
response = resource["/post"].post(form: {:image => file})

JSON payload

crest does not speak JSON natively, so serialize your form to a string before passing it to crest.

Crest.post(
  "http://httpbin.org/post",
  headers: {"Content-Type" => "application/json"},
  form: {:foo => "bar"}.to_json
)

Headers

Request headers can be set by passing a hash containing keys and values representing header names and values:

response = Crest.get(
  "http://httpbin.org/bearer",
  headers: {"Authorization" => "Bearer cT0febFoD5lxAlNAXHo6g"}
)
response.headers
# => {"Authorization" => ["Bearer cT0febFoD5lxAlNAXHo6g"]}

Cookies

Request and Response objects know about HTTP cookies, and will automatically extract and set headers for them as needed:

response = Crest.get(
  "http://httpbin.org/cookies/set",
  params: {"k1" => "v1", "k2" => "v2"}
)
response.cookies
# => {"k1" => "v1", "k2" => "v2"}

response = Crest.get(
  "http://httpbin.org/cookies",
  cookies: {"k1" => "v1"}
)
response.cookies
# => {"k1" => "v1"}

Basic authentication

For basic access authentication for an HTTP user agent you should to provide a user name and password when making a request.

Crest.get(
  "http://httpbin.org/basic-auth/user/passwd",
  user: "user",
  password: "passwd"
)
# curl -L --user user:passwd http://httpbin.org/basic-auth/user/passwd

Proxy

If you need to use a proxy, you can configure individual requests with the proxy host and port arguments to any request method:

Crest.get(
  "http://httpbin.org/ip",
  p_addr: "localhost",
  p_port: 3128
)

To use HTTP Basic Auth with your proxy, use next syntax:

Crest.get(
  "http://httpbin.org/ip",
  p_addr: "localhost",
  p_port: 3128,
  p_user: "user",
  p_pass: "qwerty"
)

Logging

Logger class is completely taken from halite shard. Thanks icyleaf!

By default, the Crest does not enable logging. You can enable it per request by setting logging: true:

Crest.get("http://httpbin.org/get", logging: true)

Filter sensitive information from logs with a regex matcher

resource = Crest::Request.get("http://httpbin.org/get", params: {api_key => "secret"}, logging: true) do |request|
  request.logger.filter(/(api_key=)(\w+)/, "\\1[REMOVED]")
end

# => crest | 2018-07-04 14:49:49 | GET | http://httpbin.org/get?api_key=[REMOVED]

Customize logging

You can create the custom logger by integration Crest::Logger abstract class. Here has two methods must be implement: Crest::Logger.request and Crest::Logger.response.

class MyLogger < Crest::Logger
  def request(request)
    @logger.info ">> | %s | %s" % [request.method, request.url]
  end

  def response(response)
    @logger.info "<< | %s | %s" % [response.status_code, response.url]
  end
end

Crest.get("http://httpbin.org/get", logging: true, logger: MyLogger.new)

Resource

A Crest::Resource class can be instantiated for access to a RESTful resource, including authentication, proxy and logging.

Additionally, you can set default params and headers separately. So can use Crest::Resource to share common headers and params.

The final headers and params consist of:

  • default headers from initializer
  • headers provided in call method (get, post, etc)

This is especially useful if you wish to define your site in one place and call it in multiple locations.

resource = Crest::Resource.new(
  "http://httpbin.org",
  params: {"key" => "value"},
  headers: {"Content-Type" => "application/json"}
)

response["/get"].get(
  headers: {"Auth-Token" => "secret"}
)

response["/post"].post(
  form: {:height => 100, "width" => "100"},
  params: {:secret => "secret"}
)

Use the [] syntax to allocate subresources:

site = Crest::Resource.new("http://httpbin.org")

site["/post"].post({:param1 => "value1", :param2 => "value2"})
# curl -L --data "param1=value1&param2=value2" -X POST http://httpbin.org/post

You can pass suburl through Request#http_verb methods:

site = Crest::Resource.new("http://httpbin.org")

site.post("/post", form: {:param1 => "value1", :param2 => "value2"})
# curl -L --data "param1=value1&param2=value2" -X POST http://httpbin.org/post

site.get("/get", params: {:status => "active"})
# curl -L http://httpbin.org/get?status=active

A block can be passed to the Crest::Resource instance.

This block will then be called with the Crest::Resource.

resource = Crest::Resource.new("http://httpbin.org") do |resource|
  resource.headers.merge!({"foo" => "bar"})
end

resource["/headers"].get

With HTTP basic authentication:

resource = Crest::Resource.new(
  "http://httpbin.org/basic-auth/user/passwd",
  user: "user",
  password: "passwd"
)

With Proxy authentication:

resource = Crest::Resource.new(
  "http://httpbin.org/get",
  p_host: "localhost",
  p_port: 3128
)

Exceptions

  • for result codes between 200 and 207, a Crest::Response will be returned
  • for result codes 301, 302, 303 or 307, the redirection will be followed and the request transformed into a GET
  • for other cases, a Crest::RequestFailed holding the Response will be raised
  • call .response on the exception to get the server's response
Crest.get("http://httpbin.org/status/404")
# => HTTP status code 404: Not Found (Crest::NotFound)

begin
  Crest.get("http://httpbin.org/status/404")
rescue ex : Crest::NotFound
  puts ex.response
end

To not raise exceptions but return the Crest::Response you can set :handle_errors => false.

response = Crest.get("http://httpbin.org/status/404", handle_errors: false)
response.status_code # => 404

Redirection

By default, crest will follow HTTP 30x redirection requests.

To disable automatic redirection, set :max_redirects => 0.

Crest::Request.execute(method: :get, url: "http://httpbin.org/redirect/1", max_redirects: 0)
# => Crest::Found: 302 Found

Result handling

The result of a Crest::Request is a Crest::Response object.

Response objects have several useful methods.

  • Response#body: The response body as a string
  • Response#status_code: The HTTP response code
  • Response#headers: A hash of HTTP response headers
  • Response#cookies: A hash of HTTP cookies set by the server
  • Response#request: The Crest::Request object used to make the request
  • Response#http_client_res: The HTTP::Client::Response object
  • Response#history: A list of each response received in a redirection chain

Development

Install dependencies:

shards

To run test:

make test

Workbook

crystal play
open http://localhost:8080

Then select the Workbook -> Requests from the menu.

Contributing

  1. Fork it ( https://github.com/mamantoha/crest/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request

Contributors

License

Copyright: 2017-2018 Anton Maminov (anton.maminov@gmail.com)

This library is distributed under the MIT license. Please see the LICENSE file.