Faraday

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Faraday is an HTTP client lib that provides a common interface over many adapters (such as Net::HTTP) and embraces the concept of Rack middleware when processing the request/response cycle.

Faraday supports these adapters out of the box:

Adapters are slowly being moved into their own gems, or bundled with HTTP clients:

It also includes a Rack adapter for hitting loaded Rack applications through Rack::Test, and a Test adapter for stubbing requests by hand.

API documentation

Available at rubydoc.info.

Usage

Basic Use

ruby response = Faraday.get 'http://sushi.com/nigiri/sake.json' A simple get request can be performed by using the syntax described above. This works if you don’t need to set up anything; you can roll with just the default middleware stack and default adapter (see Faraday::RackBuilder#initialize).

A more flexible way to use Faraday is to start with a Connection object. If you want to keep the same defaults, you can use this syntax:

ruby conn = Faraday.new(:url => 'http://www.example.com') response = conn.get '/users' # GET http://www.example.com/users'

Connections can also take an options hash as a parameter or be configured by using a block. Checkout the section called Advanced middleware usage for more details about how to use this block for configurations. Since the default middleware stack uses url_encoded middleware and default adapter, use them on building your own middleware stack.

```ruby conn = Faraday.new(:url => ‘http://sushi.com’) do |faraday| faraday.request :url_encoded # form-encode POST params faraday.response :logger # log requests to $stdout faraday.adapter Faraday.default_adapter # make requests with Net::HTTP end

Filter sensitive information from logs with a regex matcher

conn = Faraday.new(:url => ‘http://sushi.com/api_key=s3cr3t’) do |faraday| faraday.request :url_encoded # form-encode POST params faraday.response :logger do | logger | logger.filter(/(api_key=)(\w+)/,’\1[REMOVED]’) end faraday.adapter Faraday.default_adapter # make requests with Net::HTTP end ```

Once you have the connection object, use it to make HTTP requests. You can pass parameters to it in a few different ways:

```ruby ## GET ##

response = conn.get ‘/nigiri/sake.json’ # GET http://sushi.com/nigiri/sake.json response.body

conn.get ‘/nigiri’, { :name => ‘Maguro’ } # GET http://sushi.com/nigiri?name=Maguro

conn.get do |req| # GET http://sushi.com/search?page=2&limit=100 req.url ‘/search’, :page => 2 req.params[‘limit’] = 100 end

POST

conn.post ‘/nigiri’, { :name => ‘Maguro’ } # POST “name=maguro” to http://sushi.com/nigiri ```

Some configuration options can be adjusted per request:

```ruby # post payload as JSON instead of “www-form-urlencoded” encoding: conn.post do |req| req.url ‘/nigiri’ req.headers[‘Content-Type’] = ‘application/json’ req.body = ‘{ “name”: “Unagi” }’ end

Per-request options

conn.get do |req| req.url ‘/search’ req.options.timeout = 5 # open/read timeout in seconds req.options.open_timeout = 2 # connection open timeout in seconds end ```

And you can inject arbitrary data into the request using the context option:

```ruby # Anything you inject using context option will be available in the env on all middlewares

conn.get do |req| req.url ‘/search’ req.options.context = { foo: ‘foo’, bar: ‘bar’ } end ```

Changing how parameters are serialized

Sometimes you need to send the same URL parameter multiple times with different values. This requires manually setting the parameter encoder and can be done on either per-connection or per-request basis.

```ruby # per-connection setting conn = Faraday.new :request => { :params_encoder => Faraday::FlatParamsEncoder }

conn.get do |req| # per-request setting: # req.options.params_encoder = my_encoder req.params[‘roll’] = [‘california’, ‘philadelphia’] end # GET ‘http://sushi.com?roll=california&roll=philadelphia’ ```

The value of Faraday params_encoder can be any object that responds to:

  • encode(hash) #=> String
  • decode(string) #=> Hash

The encoder will affect both how query strings are processed and how POST bodies get serialized. The default encoder is Faraday::NestedParamsEncoder.

Authentication

Basic and Token authentication are handled by Faraday::Request::BasicAuthentication and Faraday::Request::TokenAuthentication respectively. These can be added as middleware manually or through the helper methods.

```ruby Faraday.new(…) do |conn| conn.basic_auth(‘username’, ‘password’) end

Faraday.new(…) do |conn| conn.token_auth(‘authentication-token’) end ```

Proxy

Faraday will try to automatically infer the proxy settings from your system using URI#find_proxy. This will retrieve them from environment variables such as http_proxy, ftp_proxy, no_proxy, etc. If for any reason you want to disable this behaviour, you can do so by setting the global varibale ignore_env_proxy:

ruby Faraday.ignore_env_proxy = true

You can also specify a custom proxy when initializing the connection

ruby Faraday.new('http://www.example.com', :proxy => 'http://proxy.com')

Advanced middleware usage

The order in which middleware is stacked is important. Like with Rack, the first middleware on the list wraps all others, while the last middleware is the innermost one, so that must be the adapter.

```ruby Faraday.new(…) do |conn| # POST/PUT params encoders: conn.request :multipart conn.request :url_encoded

# Last middleware must be the adapter: conn.adapter :net_http end ```

This request middleware setup affects POST/PUT requests in the following way:

  1. Request::Multipart checks for files in the payload, otherwise leaves everything untouched;
  2. Request::UrlEncoded encodes as “application/x-www-form-urlencoded” if not already encoded or of another type

Swapping middleware means giving the other priority. Specifying the “Content-Type” for the request is explicitly stating which middleware should process it.

Examples:

```ruby # uploading a file: payload[:profile_pic] = Faraday::UploadIO.new(‘/path/to/avatar.jpg’, ‘image/jpeg’)

“Multipart” middleware detects files and encodes with “multipart/form-data”:

conn.put ‘/profile’, payload ```

Writing middleware

Middleware are classes that implement a call instance method. They hook into the request/response cycle.

```ruby def call(request_env) # do something with the request # request_env[:request_headers].merge!(…)

@app.call(request_env).on_complete do |response_env| # do something with the response # response_env[:response_headers].merge!(…) end end ```

It’s important to do all processing of the response only in the on_complete block. This enables middleware to work in parallel mode where requests are asynchronous.

The env is a hash with symbol keys that contains info about the request and, later, response. Some keys are:

``` # request phase :method - :get, :post, … :url - URI for the current request; also contains GET parameters :body - POST parameters for :post/:put requests :request_headers

response phase

:status - HTTP response status code, such as 200 :body - the response body :response_headers ```

Ad-hoc adapters customization

Faraday is intended to be a generic interface between your code and the adapter. However, sometimes you need to access a feature specific to one of the adapters that is not covered in Faraday’s interface.

When that happens, you can pass a block when specifying the adapter to customize it. The block parameter will change based on the adapter you’re using. See below for some examples.

NetHttp

ruby conn = Faraday.new(...) do |f| f.adapter :net_http do |http| # yields Net::HTTP http.idle_timeout = 100 http.verify_callback = lambda do | preverify_ok, cert_store | # do something here... end end end

NetHttpPersistent

ruby conn = Faraday.new(...) do |f| f.adapter :net_http_persistent do |http| # yields Net::HTTP::Persistent http.idle_timeout = 100 http.retry_change_requests = true end end

Patron

ruby conn = Faraday.new(...) do |f| f.adapter :patron do |session| # yields Patron::Session session.max_redirects = 10 end end

HTTPClient

ruby conn = Faraday.new(...) do |f| f.adapter :httpclient do |client| # yields HTTPClient client.keep_alive_timeout = 20 client.ssl_config.timeout = 25 end end

Using Faraday for testing

```ruby # It’s possible to define stubbed request outside a test adapter block. stubs = Faraday::Adapter::Test::Stubs.new do |stub| stub.get(‘/tamago’) { |env| [200, {}, ‘egg’] } end

You can pass stubbed request to the test adapter or define them in a block

# or a combination of the two. test = Faraday.new do |builder| builder.adapter :test, stubs do |stub| stub.get(‘/ebi’) { |env| [ 200, {}, ‘shrimp’ ]} end end

It’s also possible to stub additional requests after the connection has

# been initialized. This is useful for testing. stubs.get(‘/uni’) { |env| [ 200, {}, ‘urchin’ ]}

resp = test.get ‘/tamago’ resp.body # => ‘egg’ resp = test.get ‘/ebi’ resp.body # => ‘shrimp’ resp = test.get ‘/uni’ resp.body # => ‘urchin’ resp = test.get ‘/else’ #=> raises “no such stub” error

If you like, you can treat your stubs as mocks by verifying that all of

# the stubbed calls were made. NOTE that this feature is still fairly # experimental: It will not verify the order or count of any stub, only that # it was called once during the course of the test. stubs.verify_stubbed_calls ```

Supported Ruby versions

This library aims to support and is tested against the following Ruby implementations:

If something doesn’t work on one of these Ruby versions, it’s a bug.

This library may inadvertently work (or seem to work) on other Ruby implementations, however support will only be provided for the versions listed above.

If you would like this library to support another Ruby version, you may volunteer to be a maintainer. Being a maintainer entails making sure all tests run and pass on that implementation. When something breaks on your implementation, you will be responsible for providing patches in a timely fashion. If critical issues for a particular implementation exist at the time of a major release, support for that Ruby version may be dropped.

Contribute

Do you want to contribute to Faraday? Open the issues page and check for the any volunteer? label! But before you start coding, please read our Contributing Guide

Copyright (c) 2009-2017 Rick Olson, Zack Hobson. See LICENSE for details.