Create Action

create-action

Use this skill when creating or reviewing Hanami 2.x Actions.

Core principle: One Action = one HTTP endpoint.

Quick Reference (jump to workflow step)

Workflow: Creating a New Action

1. Generate the Action file. One Action per file — generate Index, Show, Create, Update, Destroy as separate classes:

   hanami generate action Users::Index
   

2. Define a Params block to validate and coerce input. Invalid params should halt 422 before any business logic runs:

   class Create < MyApp::Action
     params do
       required(:user).hash do
         required(:name).filled(:string)
         required(:email).filled(:string)
       end
     end
   
     def handle(request, response)
       halt 422, { errors: request.params.errors.to_h }.to_json unless request.params.valid?
       # proceed with valid params
     end
   end
   

3. Implement #handle — Actions are HTTP handlers only; delegate all business logic to repositories, interactors, or service objects. Actions have only #handle; never use instance variables for state sharing between methods:

   # app/actions/users/index.rb
   # frozen_string_literal: true
   
   module MyApp
     module Actions
       module Users
         class Index < MyApp::Action
           include Deps["repos.user_repo"]
   
           def handle(request, response)
             response.render(view, users: user_repo.all)
           end
         end
       end
     end
   end
   

4. Inject dependencies via Deps — never access the container directly (Hanami.app['key'] is untestable and forbidden):

   include Deps["repos.user_repo", "views.users.show"]
   

5. Wire error handling — use halt for early returns. Log errors and return meaningful responses; never swallow exceptions silently:

   def handle(request, response)
     user = user_repo.by_id(request.params[:id]).one
     halt 404, { error: "User not found" }.to_json unless user
     response.render(view, user: user)
   end
   

6. Set appropriate HTTP status codes where they differ from defaults:

   • 201 for successful creates
   • 204 for successful deletes with no body
   • 422 for validation errors

   To return JSON: response.format = :json; response.body = data.to_json To redirect: response.redirect_to("/path")

7. Validate with a request spec (see write-request-spec skill) before considering the action complete.

Integration