Add support for form data

[JoelQ]

🧰 What's being changed?

According to HAR, data submitted with multipart/form-data or
application/x-www-form-urlencoded MIME types should be formatted as
key-value pairs under a request.postData.params key rather than the
request.postData.text key we use for other request types like JSON.

Additionally, we want to parse the data and filter out keys based on the
user's preferences.

🧪 Testing

Create a sample Rack app like:

# config.ru

$LOAD_PATH << File.expand_path("../path/to/metrics-sdks/packages/ruby/lib", __FILE__)
require "readme/metrics"

class ApiApp
  def call(env)
    [200, {"Content-Length" => "2"}, ["Ok"]]
  end
end

map "/api" do
  use Readme::Metrics, reject_params: ["reject"], buffer_length: 1, api_key: "YOUR_KEY_HERE" do
    { id: 1, label: "Joël", email: "[email protected]" }
  end
  run ApiApp.new
end

run it via:

$ rackup

and make a cURL request to it:

$ curl 'http://localhost:9292/api/foo' -X POST -d "reject=1&id=2&num=3"

Expect to see the request show up in the Readme dashboard with individual parameters. Also expect that the rejected parameter is filtered out.

Contrast this with the way JSON requests come through as a single -d flag in the generated cURL command:

[thestrabusiness]

👍