---

name: active-interaction-coder description: Implement typed business operations with ActiveInteraction. Covers input types, composition, controller patterns, and testing.

ActiveInteraction Coder

Typed business operations as the structured alternative to service objects.

Why ActiveInteraction Over Service Objects

Setup

Copy# Gemfile
gem "active_interaction", "~> 5.3"

Simple Interaction

Copy# app/interactions/users/create.rb
module Users
  class Create < ActiveInteraction::Base
    # Typed inputs
    string :email
    string :name
    string :password, default: nil

    # Validations
    validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }
    validates :name, presence: true

    # Main logic
    def execute
      user = User.create!(
        email: email,
        name: name,
        password: password || SecureRandom.alphanumeric(32)
      )

      UserMailer.welcome(user).deliver_later
      user  # Return value becomes outcome.result
    end
  end
end

Running Interactions

Copy# In controller
def create
  outcome = Users::Create.run(
    email: params[:email],
    name: params[:name]
  )

  if outcome.valid?
    redirect_to outcome.result, notice: "User created"
  else
    @errors = outcome.errors
    render :new, status: :unprocessable_entity
  end
end

# With bang method (raises on error)
user = Users::Create.run!(email: "user@example.com", name: "John")

Input Types

Copyclass MyInteraction < ActiveInteraction::Base
  # Primitives
  string :name
  integer :age
  float :price
  boolean :active
  symbol :status

  # Date/Time
  date :birthday
  time :created_at
  date_time :scheduled_at

  # Complex types
  array :tags
  hash :metadata

  # Model instances
  object :user, class: User

  # Typed arrays
  array :emails, default: [] do
    string
  end

  # Optional with default
  string :optional_field, default: nil
  integer :count, default: 0
end

Composing Interactions

Copymodule Users
  class Register < ActiveInteraction::Base
    string :email, :name, :password

    def execute
      # Compose calls another interaction
      user = compose(Users::Create,
        email: email,
        name: name,
        password: password
      )

      # Errors automatically merged if nested fails
      compose(Users::SendWelcomeEmail, user: user)
      user
    end
  end
end

Controller Pattern

Copyclass ArticlesController < ApplicationController
  def create
    outcome = Articles::Create.run(
      title: params[:article][:title],
      body: params[:article][:body],
      author: current_user
    )

    if outcome.valid?
      redirect_to article_path(outcome.result), notice: "Article created"
    else
      @article = Article.new(article_params)
      @article.errors.merge!(outcome.errors)
      render :new, status: :unprocessable_entity
    end
  end
end

Testing Interactions

CopyRSpec.describe Users::Create do
  let(:valid_params) { { email: "user@example.com", name: "John" } }

  it "creates user with valid inputs" do
    expect { described_class.run(valid_params) }
      .to change(User, :count).by(1)
  end

  it "returns valid outcome" do
    outcome = described_class.run(valid_params)
    expect(outcome).to be_valid
    expect(outcome.result).to be_a(User)
  end

  it "validates email format" do
    outcome = described_class.run(valid_params.merge(email: "invalid"))
    expect(outcome).not_to be_valid
    expect(outcome.errors[:email]).to be_present
  end
end

Advanced Patterns

For composition, error handling, and custom types see:

• references/active-interaction.md