Streaming: callbacks

[alexrudall]

Is your feature request related to a problem? Please describe.

• Problem: No way to respond to success and error when streaming

Describe the solution you'd like
Add new callbacks to stream:

• on_data
• on_success
• on_error

Would love feedback on this. Thanks!

[itsderek23]

This would be great. Right now I'm using a version of #256 to handle errors.

[codenamev]

The OpenAI API includes a signal for when a "success" happens in the form of finish_reason. I've been using a "Streamer" object that I pass to this gem's stream param:

class OpenAiStreamer
  attr_reader :on_complete, :chunk, :content

  def initialize(on_complete: nil)
    @content = ""
    @on_complete = on_complete
    @completed = false
  end

  def call(chunk)
    return if @completed

    @chunk = chunk
    @content << (@chunk || {}).dig("choices", 0, "delta", "content")

    # do something with the chunk...

    if finish_reason.present?
      @completed = true
      on_complete.call(self)
      return chunk
    end
  end

  def finish_reason
    (@chunk || {}).dig("choices", 0, "finish_reason")
  end
end

def success_callback(streamer)
  puts "Completed chat: #{streamer.content}"
end

client = OpenAI::Client.new
client.chat(
  parameters: {
    model: "gpt-3.5-turbo",
    messages: [...],
    stream: OpenAiStreamer.new(on_complete: method(:success_callback))
  }
)

It has been helpful in chaining responses, but I see it more as a patch. I'm not sure I'm sold on the interface, but it works 🤷

[alexrudall]

Exception handling released in v6