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https://github.com/icyleaf/halite

💎HTTP Requests Client with a chainable REST API, built-in sessions and middlewares.
https://github.com/icyleaf/halite

chainable-methods crystal http-client http-interceptor http-logger http-middleware http-session

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💎HTTP Requests Client with a chainable REST API, built-in sessions and middlewares.

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![halite-logo](https://github.com/icyleaf/halite/raw/master/halite-logo-small.png)



# Halite



[![Language](https://img.shields.io/badge/language-crystal-776791.svg)](https://github.com/crystal-lang/crystal)

[![Tag](https://img.shields.io/github/tag/icyleaf/halite.svg)](https://github.com/icyleaf/halite/blob/master/CHANGELOG.md)

[![Source](https://img.shields.io/badge/source-github-brightgreen.svg)](https://github.com/icyleaf/halite/)

[![Document](https://img.shields.io/badge/document-api-brightgreen.svg)](https://icyleaf.github.io/halite/)

[![Build Status](https://github.com/icyleaf/halite/workflows/Linux%20CI/badge.svg)](https://github.com/icyleaf/halite/actions?query=workflow%3A%22Linux+CI%22)



HTTP Requests with a chainable REST API, built-in sessions and middleware written by [Crystal](https://crystal-lang.org/).

Inspired from the **awesome** Ruby's [HTTP](https://github.com/httprb/http)/[RESTClient](https://github.com/rest-client/rest-client)

and Python's [requests](https://github.com/requests/requests).



Build in Crystal version `>= 1.0.0`, this document valid with latest commit.



## Index



- [Installation](#installation)

- [Usage](#usage)

  - [Making Requests](#making-requests)

  - [Passing Parameters](#passing-parameters)

    - [Query string parameters](#query-string-parameters)

    - [Form data](#form-data)

    - [File uploads (via form data)](#file-uploads-via-form-data)

    - [JSON data](#json-data)

    - [Raw String](#raw-string)

  - [Passing advanced options](#passing-advanced-options)

    - [Auth](#auth)

    - [User Agent](#user-agent)

    - [Headers](#headers)

    - [Cookies](#cookies)

    - [Redirects and History](#redirects-and-history)

    - [Timeout](#timeout)

  - [HTTPS](#https)

  - [Response Handling](#response-handling)

    - [Response Content](#response-content)

    - [JSON Content](#json-content)

    - [Parsing Content](#parsing-content)

    - [Binary Data](#binary-data)

  - [Error Handling](#error-handling)

    - [Raise for status code](#raise-for-status-code)

- [Middleware](#middleware)

  - [Write a simple feature](#write-a-simple-feature)

  - [Write a interceptor](#write-a-interceptor)

- [Advanced Usage](#advanced-usage)

  - [Configuring](#configuring)

  - [Endpoint](#endpoint)

  - [Sessions](#sessions)

  - [Streaming Requests](#streaming-requests)

  - [Logging](#logging)

  - [Local Cache](#local-cache)

  - [Link Headers](#link-headers)



## Installation



Add this to your application's `shard.yml`:



```yaml

dependencies:

  halite:

    github: icyleaf/halite

```



## Usage



```crystal

require "halite"

```



### Making Requests



Make a GET request:



```crystal

# Direct get url

Halite.get("http://httpbin.org/get")



# Support NamedTuple as query params

Halite.get("http://httpbin.org/get", params: {

  language: "crystal",

  shard: "halite"

})



# Also support Hash as query params

Halite.get("http://httpbin.org/get", headers: {

    "Private-Token" => "T0k3n"

  }, params: {

    "language" => "crystal",

    "shard" => "halite"

  })



# And support chainable

Halite.header(private_token: "T0k3n")

      .get("http://httpbin.org/get", params: {

        "language" => "crystal",

        "shard" => "halite"

      })

```



See also all [chainable methods](https://icyleaf.github.io/halite/Halite/Chainable.html).



Many other HTTP methods are available as well:



- `get`

- `head`

- `post`

- `put`

- `delete`

- `patch`

- `options`



### Passing Parameters



#### Query string parameters



Use the `params` argument to add query string parameters to requests:



```crystal

Halite.get("http://httpbin.org/get", params: { "firstname" => "Olen", "lastname" => "Rosenbaum" })

```



#### Form data



Use the `form` argument to pass data serialized as form encoded:



```crystal

Halite.post("http://httpbin.org/post", form: { "firstname" => "Olen", "lastname" => "Rosenbaum" })

```



#### File uploads (via form data)



To upload files as if form data, construct the form as follows:



```crystal

Halite.post("http://httpbin.org/post", form: {

  "username" => "Quincy",

  "avatar" => File.open("/Users/icyleaf/quincy_avatar.png")

})

```



It is possible to upload multiple files:



```crystal

Halite.post("http://httpbin.org/post", form: {

  photos: [

    File.open("/Users/icyleaf/photo1.png"),

    File.open("/Users/icyleaf/photo2.png")

  ],

  album_name: "samples"

})

```



Or pass the name with `[]`:



```crystal

Halite.post("http://httpbin.org/post", form: {

  "photos[]" => [

    File.open("/Users/icyleaf/photo1.png"),

    File.open("/Users/icyleaf/photo2.png")

  ],

  "album_name" => "samples"

})

```



Multiple files can also be uploaded using both ways above, it depend on web server.



#### JSON data



Use the `json` argument to pass data serialized as body encoded:



```crystal

Halite.post("http://httpbin.org/post", json: { "firstname" => "Olen", "lastname" => "Rosenbaum" })

```



#### Raw String



Use the `raw` argument to pass raw string as body and set the `Content-Type` manually:



```crystal

# Set content-type to "text/plain" by default

Halite.post("http://httpbin.org/post", raw: "name=Peter+Lee&address=%23123+Happy+Ave&language=C%2B%2B")



# Set content-type manually

Halite.post("http://httpbin.org/post",

  headers: {

    "content-type" => "application/json"

  },

  raw: %Q{{"name":"Peter Lee","address":"23123 Happy Ave","language":"C++"}}

)

```



### Passing advanced options



#### Auth



Use the `#basic_auth` method to perform [HTTP Basic Authentication](http://tools.ietf.org/html/rfc2617) using a username and password:



```crystal

Halite.basic_auth(user: "user", pass: "p@ss").get("http://httpbin.org/get")



# We can pass a raw authorization header using the auth method:

Halite.auth("Bearer dXNlcjpwQHNz").get("http://httpbin.org/get")

```



#### User Agent



Use the `#user_agent` method to overwrite default one:



```crystal

Halite.user_agent("Crystal Client").get("http://httpbin.org/user-agent")

```



#### Headers



Here are two way to passing headers data:



##### 1. Use the `#headers` method



```crystal

Halite.headers(private_token: "T0k3n").get("http://httpbin.org/get")



# Also support Hash or NamedTuple

Halite.headers({ "private_token" => "T0k3n" }).get("http://httpbin.org/get")



# Or

Halite.headers({ private_token: "T0k3n" }).get("http://httpbin.org/get")

```



##### 2. Use the `headers` argument in the available request method:



```crystal

Halite.get("http://httpbin.org/anything" , headers: { private_token: "T0k3n" })



Halite.post("http://httpbin.org/anything" , headers: { private_token: "T0k3n" })

```



#### Cookies



##### Passing cookies in requests



The `Halite.cookies` option can be used to configure cookies for a given request:



```crystal

Halite.cookies(session_cookie: "6abaef100b77808ceb7fe26a3bcff1d0")

      .get("http://httpbin.org/headers")

```



##### Get cookies in requests



To obtain the cookies(cookie jar) for a given response, call the `#cookies` method:



```crystal

r = Halite.get("http://httpbin.org/cookies?set?session_cookie=6abaef100b77808ceb7fe26a3bcff1d0")

pp r.cookies

# => ##}>

```



#### Redirects and History



##### Automatically following redirects



The `Halite.follow` method can be used for automatically following redirects(Max up to 5 times):



```crystal

# Set the cookie and redirect to http://httpbin.org/cookies

Halite.follow

      .get("http://httpbin.org/cookies/set/name/foo")

```



##### Limiting number of redirects



As above, set over 5 times, it will raise a `Halite::TooManyRedirectsError`, but you can change less if you can:



```crystal

Halite.follow(2)

      .get("http://httpbin.org/relative-redirect/5")

```



##### Disabling unsafe redirects



It only redirects with `GET`, `HEAD` request and returns a `300`, `301`, `302` by default, otherwise it will raise a `Halite::StateError`.

We can disable it to set `:strict` to `false` if we want any method(verb) requests, in which case the `GET` method(verb) will be used for

that redirect:



```crystal

Halite.follow(strict: false)

      .post("http://httpbin.org/relative-redirect/5")

```



##### History



`Response#history` property list contains the `Response` objects that were created in order to complete the request.

The list is ordered from the oldest to most recent response.



```crystal

r = Halite.follow

          .get("http://httpbin.org/redirect/3")



r.uri

# => http://httpbin.org/get



r.status_code

# => 200



r.history

# => [

#      # "/relative-redirect/2" ...>,

#      # "/relative-redirect/1" ...>,

#      # "/get" ...>,

#      # "application/json" ...>

#    ]

```



**NOTE**: It contains the `Response` object if you use `history` and HTTP was not a `30x`, For example:



```crystal

r = Halite.get("http://httpbin.org/get")

r.history.size # => 0



r = Halite.follow

          .get("http://httpbin.org/get")

r.history.size # => 1

```



#### Timeout



By default, the Halite does not enforce timeout on a request.

We can enable per operation timeouts by configuring them through the chaining API.



The `connect` timeout is the number of seconds Halite will wait for our client to establish a connection to a remote server call on the socket.



Once our client has connected to the server and sent the HTTP request,

the `read` timeout is the number of seconds the client will wait for the server to send a response.



```crystal

# Separate set connect and read timeout

Halite.timeout(connect: 3.0, read: 2.minutes)

      .get("http://httpbin.org/anything")



# Boath set connect and read timeout

# The timeout value will be applied to both the connect and the read timeouts.

Halite.timeout(5)

      .get("http://httpbin.org/anything")

```



### HTTPS



The Halite supports HTTPS via Crystal's built-in OpenSSL module. All you have to do in order to use HTTPS is pass in an https://-prefixed URL.



To use client certificates, you can pass in a custom `OpenSSL::SSL::Context::Client` object containing the certificates you wish to use:



```crystal

tls = OpenSSL::SSL::Context::Client.new

tls.ca_certificates = File.expand_path("~/client.crt")

tls.private_key = File.expand_path("~/client.key")



Halite.get("https://httpbin.org/anything", tls: tls)

```



### Response Handling



After an HTTP request, `Halite::Response` object have several useful methods. (Also see the [API documentation](https://icyleaf.github.io/halite/Halite/Response.html)).



- **#body**: The response body.

- **#body_io**: The response body io only available in streaming requests.

- **#status_code**: The HTTP status code.

- **#content_type**: The content type of the response.

- **#content_length**: The content length of the response.

- **#cookies**: A `HTTP::Cookies` set by server.

- **#headers**: A `HTTP::Headers` of the response.

- **#links**: A list of `Halite::HeaderLink` set from headers.

- **#parse**: (return value depends on MIME type) parse the body using a parser defined for the `#content_type`.

- **#to_a**: Return a `Hash` of status code, response headers and body as a string.

- **#to_raw**: Return a raw of response as a string.

- **#to_s**: Return response body as a string.

- **#version**: The HTTP version.



#### Response Content



We can read the content of the server's response by call `#body`:



```crystal

r = Halite.get("http://httpbin.org/user-agent")

r.body

# => {"user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36"}

```



The `gzip` and `deflate` transfer-encodings are automatically decoded for you.

And requests will automatically decode content from the server. Most unicode charsets are seamlessly decoded.



#### JSON Content



There’s also a built-in a JSON adapter, in case you’re dealing with JSON data:



```crystal

r = Halite.get("http://httpbin.org/user-agent")

r.parse("json")

r.parse # simplily by default

# => {

# =>   "user-agent" => "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36"

# => }

```



#### Parsing Content



`Halite::Response` has a MIME type adapter system that you can use a decoder to parse the content,

we can inherit `Halite::MimeTypes::Adapter` to make our adapter:



```crystal

# Define a MIME type adapter

class YAMLAdapter < Halite::MimeType::Adapter

  def decode(string)

    YAML.parse(string)

  end



  def encode(obj)

    obj.to_yaml

  end

end



# Register to Halite to invoke

Halite::MimeType.register YAMLAdapter.new, "application/x-yaml", "yaml", "yml"



# Test it!

r = Halite.get "https://raw.githubusercontent.com/icyleaf/halite/master/shard.yml"

r.parse("yaml") # or "yml"

# => {"name" => "halite", "version" => "0.4.0", "authors" => ["icyleaf "], "crystal" => "0.25.0", "license" => "MIT"}

```



#### Binary Data



Store binary data (eg, `application/octet-stream`) to file, you can use [streaming requests](#streaming-requests):



```crystal

Halite.get("https://github.com/icyleaf/halite/archive/master.zip") do |response|

  filename = response.filename || "halite-master.zip"

  File.open(filename, "w") do |file|

    IO.copy(response.body_io, file)

  end

end

```



### Error Handling



- For any status code, a `Halite::Response` will be returned.

- If request timeout, a `Halite::TimeoutError` will be raised.

- If a request exceeds the configured number of maximum redirections, a `Halite::TooManyRedirectsError` will raised.

- If request uri is http and configured tls context, a `Halite::RequestError` will raised.

- If request uri is invalid, a `Halite::ConnectionError`/`Halite::UnsupportedMethodError`/`Halite::UnsupportedSchemeError` will raised.



#### Raise for status code



If we made a bad request(a 4xx client error or a 5xx server error response), we can raise with `Halite::Response.raise_for_status`.



But, since our `status_code` was not `4xx` or `5xx`, it returns `nil` when we call it:



```crystal

urls = [

  "https://httpbin.org/status/404",

  "https://httpbin.org/status/500?foo=bar",

  "https://httpbin.org/status/200",

]



urls.each do |url|

  r = Halite.get url

  begin

    r.raise_for_status

    p r.body

  rescue ex : Halite::ClientError | Halite::ServerError

    p "[#{ex.status_code}] #{ex.status_message} (#{ex.class})"

  end

end



# => "[404] not found error with url: https://httpbin.org/status/404 (Halite::Exception::ClientError)"

# => "[500] internal server error error with url: https://httpbin.org/status/500?foo=bar (Halite::Exception::ServerError)"

# => ""

```



## Middleware



Halite now has middleware (a.k.a features) support providing a simple way to plug in intermediate custom logic

in your HTTP client, allowing you to monitor outgoing requests, incoming responses, and use it as an interceptor.



Available features:



- [Logging](#logging) (Yes, logging is based on feature, cool, aha!)

- [Local Cache](#local-cache) (local storage, speed up in development)



### Write a simple feature



Let's implement simple middleware that prints each request:



```crystal

class RequestMonister < Halite::Feature

  @label : String

  def initialize(**options)

    @label = options.fetch(:label, "")

  end



  def request(request) : Halite::Request

    puts @label

    puts request.verb

    puts request.uri

    puts request.body



    request

  end



  Halite.register_feature "request_monster", self

end

```



Then use it in Halite:



```crystal

Halite.use("request_monster", label: "testing")

      .post("http://httpbin.org/post", form: {name: "foo"})



# Or configure to client

client = Halite::Client.new do

  use "request_monster", label: "testing"

end



client.post("http://httpbin.org/post", form: {name: "foo"})



# => testing

# => POST

# => http://httpbin.org/post

# => name=foo

```



### Write a interceptor



Halite's killer feature is the **interceptor**, Use `Halite::Feature::Chain` to process with two result:



- `next`: perform and run next interceptor

- `return`: perform and return



So, you can intercept and turn to the following registered features.



```crystal

class AlwaysNotFound < Halite::Feature

  def intercept(chain)

    response = chain.perform

    response = Halite::Response.new(chain.request.uri, 404, response.body, response.headers)

    chain.next(response)

  end



  Halite.register_feature "404", self

end



class PoweredBy < Halite::Feature

  def intercept(chain)

    if response = chain.response

      response.headers["X-Powered-By"] = "Halite"

      chain.return(response)

    else

      chain

    end

  end



  Halite.register_feature "powered_by", self

end



r = Halite.use("404").use("powered_by").get("http://httpbin.org/user-agent")

r.status_code               # => 404

r.headers["X-Powered-By"]   # => Halite

r.body                      # => {"user-agent":"Halite/0.6.0"}

```



For more implementation details about the feature layer, see the [Feature](https://github.com/icyleaf/halite/blob/master/src/halite/feature.cr#L2) class and [examples](https://github.com/icyleaf/halite/tree/master/src/halite/features) and [specs](https://github.com/icyleaf/halite/blob/master/spec/spec_helper.cr#L23).



## Advanced Usage



### Configuring



Halite provides a traditional way to instance client, and you can configure any chainable methods with block:



```crystal

client = Halite::Client.new do

  # Set basic auth

  basic_auth "username", "password"



  # Enable logging

  logging true



  # Set timeout

  timeout 10.seconds



  # Set user agent

  headers user_agent: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36"

end



# You also can configure in this way

client.accept("application/json")



r = client.get("http://httpbin.org/get")

```



### Endpoint



No more given endpoint per request, use `endpoint` will make the request URI shorter, you can set it in flexible way:



```crystal

client = Halite::Client.new do

  endpoint "https://gitlab.org/api/v4"

  user_agent "Halite"

end



client.get("users")       # GET https://gitlab.org/api/v4/users



# You can override the path by using an absolute path

client.get("/users")      # GET https://gitlab.org/users

```



### Sessions



As like [requests.Session()](http://docs.python-requests.org/en/master/user/advanced/#session-objects), Halite built-in session by default.



Let's persist some cookies across requests:



```crystal

client = Halite::Client.new

client.get("http://httpbin.org/cookies/set?private_token=6abaef100b77808ceb7fe26a3bcff1d0")

client.get("http://httpbin.org/cookies")

# => 2018-06-25 18:41:05 +08:00 | request | GET    | http://httpbin.org/cookies/set?private_token=6abaef100b77808ceb7fe26a3bcff1d0

# => 2018-06-25 18:41:06 +08:00 | response | 302    | http://httpbin.org/cookies/set?private_token=6abaef100b77808ceb7fe26a3bcff1d0 | text/html

# => 

# => Redirecting...

# => 
Redirecting...


# => 
You should be redirected automatically to target URL: /cookies.  If not click the link.

# => 2018-06-25 18:41:06 +08:00 | request | GET    | http://httpbin.org/cookies

# => 2018-06-25 18:41:07 +08:00 | response | 200    | http://httpbin.org/cookies | application/json

# => {"cookies":{"private_token":"6abaef100b77808ceb7fe26a3bcff1d0"}}

```



All it support with [chainable methods](https://icyleaf.github.io/halite/Halite/Chainable.html) in the other examples list in [requests.Session](http://docs.python-requests.org/en/master/user/advanced/#session-objects).



Note, however, that chainable methods will not be persisted across requests, even if using a session. This example will only send the cookies or headers with the first request, but not the second:



```crystal

client = Halite::Client.new

r = client.cookies("username": "foobar").get("http://httpbin.org/cookies")

r.body # => {"cookies":{"username":"foobar"}}



r = client.get("http://httpbin.org/cookies")

r.body # => {"cookies":{}}

```



If you want to manually add cookies, headers (even features etc) to your session, use the methods start with `with_` in `Halite::Options`

to manipulate them:



```crystal

r = client.get("http://httpbin.org/cookies")

r.body # => {"cookies":{}}



client.options.with_cookie("username": "foobar")

r = client.get("http://httpbin.org/cookies")

r.body # => {"cookies":{"username":"foobar"}}

```



### Streaming Requests



Similar to [HTTP::Client](https://crystal-lang.org/api/0.36.1/HTTP/Client.html#streaming) usage with a block,

you can easily use same way, but Halite returns a `Halite::Response` object:



```crystal

r = Halite.get("http://httpbin.org/stream/5") do |response|

  response.status_code                  # => 200

  response.body_io.each_line do |line|

    puts JSON.parse(line)               # => {"url" => "http://httpbin.org/stream/5", "args" => {}, "headers" => {"Host" => "httpbin.org", "Connection" => "close", "User-Agent" => "Halite/0.8.0", "Accept" => "*/*", "Accept-Encoding" => "gzip, deflate"}, "id" => 0_i64}

  end

end

```



> **Warning**:

>

> `body_io` is avaiabled as an `IO` and not reentrant safe. Might throws a "Nil assertion failed" exception if there is no data in the `IO`

(such like `head` requests). Calling this method multiple times causes some of the received data being lost.

>

> One more thing, use streaming requests the response will always [enable redirect](#redirects-and-history) automatically.



### Logging



Halite does not enable logging on each request and response too.

We can enable per operation logging by configuring them through the chaining API.



By default, Halite will logging all outgoing HTTP requests and their responses(without binary stream) to `STDOUT` on DEBUG level.

You can configuring the following options:



- `logging`: Instance your `Halite::Logging::Abstract`, check [Use the custom logging](#use-the-custom-logging).

- `format`: Output format, built-in `common` and `json`, you can write your own.

- `file`: Write to file with path, works with `format`.

- `filemode`: Write file mode, works with `format`, by default is `a`. (append to bottom, create it if file is not exist)

- `skip_request_body`: By default is `false`.

- `skip_response_body`: By default is `false`.

- `skip_benchmark`: Display elapsed time, by default is `false`.

- `colorize`: Enable colorize in terminal, only apply in `common` format, by default is `true`.



> **NOTE**: `format` (`file` and `filemode`) and `logging` are conflict, you can not use both.



Let's try with it:



```crystal

# Logging json request

Halite.logging

      .get("http://httpbin.org/get", params: {name: "foobar"})



# => 2018-06-25 18:33:14 +08:00 | request  | GET    | http://httpbin.org/get?name=foobar

# => 2018-06-25 18:33:15 +08:00 | response | 200    | http://httpbin.org/get?name=foobar | 381.32ms | application/json

# => {"args":{"name":"foobar"},"headers":{"Accept":"*/*","Accept-Encoding":"gzip, deflate","Connection":"close","Host":"httpbin.org","User-Agent":"Halite/0.3.2"},"origin":"60.206.194.34","url":"http://httpbin.org/get?name=foobar"}



# Logging image request

Halite.logging

      .get("http://httpbin.org/image/png")



# => 2018-06-25 18:34:15 +08:00 | request  | GET    | http://httpbin.org/image/png

# => 2018-06-25 18:34:15 +08:00 | response | 200    | http://httpbin.org/image/png | image/png



# Logging with options

Halite.logging(skip_request_body: true, skip_response_body: true)

      .post("http://httpbin.org/get", form: {image: File.open("halite-logo.png")})



# => 2018-08-28 14:33:19 +08:00 | request  | POST   | http://httpbin.org/post

# => 2018-08-28 14:33:21 +08:00 | response | 200    | http://httpbin.org/post | 1.61s | application/json

```



#### JSON-formatted logging



It has JSON formatted for developer friendly logging.



```

Halite.logging(format: "json")

      .get("http://httpbin.org/get", params: {name: "foobar"})

```



#### Write to a log file



```crystal

# Write plain text to a log file

Log.setup("halite.file", backend: Log::IOBackend.new(File.open("/tmp/halite.log", "a")))

Halite.logging(for: "halite.file", skip_benchmark: true, colorize: false)

      .get("http://httpbin.org/get", params: {name: "foobar"})



# Write json data to a log file

Log.setup("halite.file", backend: Log::IOBackend.new(File.open("/tmp/halite.log", "a")))

Halite.logging(format: "json", for: "halite.file")

      .get("http://httpbin.org/get", params: {name: "foobar"})



# Redirect *all* logging from Halite to a file:

Log.setup("halite", backend: Log::IOBackend.new(File.open("/tmp/halite.log", "a")))

```



#### Use the custom logging



Creating the custom logging by integration `Halite::Logging::Abstract` abstract class.

Here has two methods must be implement: `#request` and `#response`.



```crystal

class CustomLogging < Halite::Logging::Abstract

  def request(request)

    @logger.info { "| >> | %s | %s %s" % [request.verb, request.uri, request.body] }

  end



  def response(response)

    @logger.info { "| << | %s | %s %s" % [response.status_code, response.uri, response.content_type] }

  end

end



# Add to adapter list (optional)

Halite::Logging.register "custom", CustomLogging.new



Halite.logging(logging: CustomLogging.new)

      .get("http://httpbin.org/get", params: {name: "foobar"})



# We can also call it use format name if you added it.

Halite.logging(format: "custom")

      .get("http://httpbin.org/get", params: {name: "foobar"})



# => 2017-12-13 16:40:13 +08:00 | >> | GET | http://httpbin.org/get?name=foobar

# => 2017-12-13 16:40:15 +08:00 | << | 200 | http://httpbin.org/get?name=foobar application/json

```



### Local Cache



Local cache feature is caching responses easily with Halite through an chainable method that is simple and elegant

yet powerful. Its aim is to focus on the HTTP part of caching and do not worrying about how stuff stored, api rate limiting

even works without network(offline).



It has the following options:



- `file`: Load cache from file. it conflict with `path` and `expires`.

- `path`: The path of cache, default is "/tmp/halite/cache/"

- `expires`: The expires time of cache, default is never expires.

- `debug`: The debug mode of cache, default is `true`



With debug mode, cached response it always included some headers information:



- `X-Halite-Cached-From`: Cache source (cache or file)

- `X-Halite-Cached-Key`: Cache key with verb, uri and body (return with cache, not `file` passed)

- `X-Halite-Cached-At`:  Cache created time

- `X-Halite-Cached-Expires-At`: Cache expired time (return with cache, not `file` passed)



```crystal

Halite.use("cache").get "http://httpbin.org/anything"     # request a HTTP

r = Halite.use("cache").get "http://httpbin.org/anything" # request from local storage

r.headers                                                 # => {..., "X-Halite-Cached-At" => "2018-08-30 10:41:14 UTC", "X-Halite-Cached-By" => "Halite", "X-Halite-Cached-Expires-At" => "2018-08-30 10:41:19 UTC", "X-Halite-Cached-Key" => "2bb155e6c8c47627da3d91834eb4249a"}}

```



### Link Headers



Many HTTP APIs feature [Link headers](https://tools.ietf.org/html/rfc5988). GitHub uses

these for [pagination](https://developer.github.com/v3/#pagination) in their API, for example:



```crystal

r = Halite.get "https://api.github.com/users/icyleaf/repos?page=1&per_page=2"

r.links

# => {"next" =>

# =>   Halite::HeaderLink(

# =>    @params={},

# =>    @rel="next",

# =>    @target="https://api.github.com/user/17814/repos?page=2&per_page=2"),

# =>  "last" =>

# =>   Halite::HeaderLink(

# =>    @params={},

# =>    @rel="last",

# =>    @target="https://api.github.com/user/17814/repos?page=41&per_page=2")}



r.links["next"]

# => "https://api.github.com/user/17814/repos?page=2&per_page=2"



r.links["next"].params

# => {}

```



## Help and Discussion



You can browse the API documents:



https://icyleaf.github.io/halite/



You can browse the all chainable methods:



https://icyleaf.github.io/halite/Halite/Chainable.html



You can browse the Changelog:



https://github.com/icyleaf/halite/blob/master/CHANGELOG.md



If you have found a bug, please create a issue here:



https://github.com/icyleaf/halite/issues/new



## How to Contribute



Your contributions are always welcome! Please submit a pull request or create an issue to add a new question, bug or feature to the list.



All [Contributors](https://github.com/icyleaf/halite/graphs/contributors) are on the wall.



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## License



[MIT License](https://github.com/icyleaf/halite/blob/master/LICENSE) © icyleaf