ExTwitter

Twitter client library for elixir. It uses erlang-oauth to call Twitter's REST API.

It only supports very limited set of functions yet. Refer to lib/extwitter.ex and test/extwitter_test.exs for available functions and examples.

Documentation

• http://hexdocs.pm/extwitter

Usage

1. Add extwitter to deps section in the mix.exs.
2. Use ExTwitter.configure to setup Twitter's OAuth authentication parameters. Refer to https://dev.twitter.com/docs for the detail.
3. Call functions in ExTwitter module (ex. ExTwitter.search("test")).

Configuration

The default behaviour is to configure using the application environment:

In config/config.exs, add:

config :extwitter, :oauth, [
   consumer_key: "",
   consumer_secret: "",
   access_token: "",
   access_token_secret: ""
]

Or manually at runtime:

ExTwitter.configure([consumer_key: "", ...])

You can also configure the current process only:

ExTwitter.configure(:process, [consumer_key: "", ...])

mix.exs

defp deps do
  [
    {:oauth, github: "tim/erlang-oauth"},
    {:extwitter, "~> 0.6"}
  ]
end

...

def application do
  [applications: [:logger, :extwitter]]
end

Sample

Sample execution on iex.

configure

$ iex -S mix
Interactive Elixir - press Ctrl+C to exit (type h() ENTER for help)

ExTwitter.configure(
   consumer_key: System.get_env("TWITTER_CONSUMER_KEY"),
   consumer_secret: System.get_env("TWITTER_CONSUMER_SECRET"),
   access_token: System.get_env("TWITTER_ACCESS_TOKEN"),
   access_token_secret: System.get_env("TWITTER_ACCESS_SECRET")
)

:ok

search

Example for normal API.

ExTwitter.search("elixir-lang", [count: 5]) |>
   Enum.map(fn(tweet) -> tweet.text end) |>
   Enum.join("\n-----\n") |>
   IO.puts

# => Tweets will be displayed in the console as follows.
@xxxx have you tried this yet?
-----
@yyyy You mean this? http://t.co/xxxx That had sailed below my radar thus far.
-----
@zzzz #elixir-lang. I'm jadams
-----
Akala ko 100 nalang kulang ko sa dark elixir para sa Barb King summoner level.
-----
@aaaa usually kasi magbbuzz lang yan pag luma na string. talaga ang elixir.
:ok

streaming

Example for streaming API.

stream = ExTwitter.stream_filter(track: "apple") |>
  Stream.map(fn(x) -> x.text end) |>
  Stream.map(fn(x) -> IO.puts "#{x}\n---------------\n" end)
Enum.to_list(stream)

# => Tweets will be displayed in the console as follows.
Apple 'iWatch' rumour round-up
---------------
Apple iPhone 4s 16GB Black Verizon - Cracked Screen, WORKS PERFECTLY!
---------------
Apple iPod nano 7th Generation (PRODUCT) RED (16 GB) (Latest Model) - Full read by
---------------
...
...

The ExTwitter.stream_control method allows to send a message to stop the stream.

# An example to stop receiving stream after 5 seconds passed.
pid = spawn(fn ->
  stream = ExTwitter.stream_filter(track: "apple")
  for tweet <- stream do
    IO.puts tweet.text
  end
end)

:timer.sleep(5000)
ExTwitter.stream_control(pid, :stop)

Twitter returns several message types (dev.twitter.com - Streaming message types). These messages are returned when receive_messages option is specified.

stream = ExTwitter.stream_sample(receive_messages: true)
for message <- stream do
  case message do
    tweet = %ExTwitter.Model.Tweet{} ->
      IO.puts "tweet = #{tweet.text}"

    deleted_tweet = %ExTwitter.Model.DeletedTweet{} ->
      IO.puts "deleted tweet = #{deleted_tweet.status[:id]}"

    limit = %ExTwitter.Model.Limit{} ->
      IO.puts "limit = #{limit.track}"

    stall_warning = %ExTwitter.Model.StallWarning{} ->
      IO.puts "stall warning = #{stall_warning.code}"

    _ ->
      IO.inspect message
  end
end

cursor

Some of Twtitter API have paging capability for retrieving large number of items through cursor. The following is an example to iteratively call the API to fetch all the items.

defmodule Retriever do
  def follower_ids(screen_name, acc \\ [], cursor \\ -1) do
    cursor = fetch_next(screen_name, cursor)
    if Enum.count(cursor.items) == 0 do
      List.flatten(acc)
    else
      follower_ids(screen_name, [cursor.items|acc], cursor.next_cursor)
    end
  end

  defp fetch_next(screen_name, cursor) do
    try do
      ExTwitter.follower_ids(screen_name, cursor: cursor)
    rescue
      e in ExTwitter.RateLimitExceededError ->
        :timer.sleep ((e.reset_in + 1) * 1000)
        fetch_next(screen_name, cursor)
    end
  end
end

ids = Retriever.follower_ids("TwitterDev")
IO.puts "Follower count for TwitterDev is #{Enum.count(ids)}."
# => Follower count for TwitterDev is 38469.

authentication / authorization

Example for authentication (Sign-in with twitter). Authorization (3-legged authorization) uses the same workflow, just swap authenticate_url for authorize_url where indicated.

# Request twitter for a new token
token = ExTwitter.request_token("http://myapp.com/twitter-callback")

# Generate the url for "Sign-in with twitter".
# For "3-legged authorization" use ExTwitter.authorize_url instead
{:ok, authenticate_url} = ExTwitter.authenticate_url(token.oauth_token)

# Copy the url, paste it in your browser and authenticate
IO.puts authenticate_url

After sign-in you will be redirected to the callback URL you configured for your app.

Example:

http://myapp.com/twitter-callback?oauth_token=copy_this&oauth_verifier=copy_this_too

Copy the oauth_token and oauth_verifier query strings from the URL and use it in the iex snippet below.

oauth_token = "copy_this"
oauth_verifier = "copy_this_too"

# Exchange for an access token
{:ok, access_token} = ExTwitter.access_token(oauth_verifier, oauth_token)

# Configure ExTwitter to use your newly obtained access token
ExTwitter.configure(
  consumer_key: System.get_env("TWITTER_CONSUMER_KEY"),
  consumer_secret: System.get_env("TWITTER_CONSUMER_SECRET"),
  access_token: access_token.oauth_token,
  access_token_secret: access_token.oauth_token_secret
)

ExTwitter.user_timeline

proxy (experimental)

Proxy for accessing twitter server can be configured as follows. It's experimental implementation and the interface can change.

In config/config.exs,

use Mix.Config

config :extwitter, :proxy, [
   server: "www-proxy.mycompany.com",
   port: 8000,
   user: "user",
   password: "password"
]

and in mix.exs,

# make sure to have :extwitter
def application do
  [applications: [:logger, :extwitter]]
end

...

# apply :oauth under parroty/erlang-oauth
defp deps do
  [
    {:oauth, github: "parroty/erlang-oauth", branch: "proxy", override: true},
    {:extwitter, github: "parroty/extwitter"}
  ]
end

and execute the following command.

$ mix deps.update oauth

The following repository have a basic sample.

• https://github.com/parroty/extwitter_proxy

Notes

run_iex.sh launches iex, with initially calling ExTwitter.configure defined as iex/dot.iex.

$ ./run_iex.sh
Erlang/OTP 17 [erts-6.3] [source] [64-bit] [smp:4:4] [async-threads:10]...
Interactive Elixir (1.0.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> (ExTwitter.search("elixir") |> List.first).text
...