# Generating a Component

Generate a Partial with closed schemas and configure host authorization before using it.

After reading this guide, you will know:

* Generate the registration, Partial and test scaffold.
* Load several components during Rails reloads.
* Replace denied policies with host authorization.

## Generate the Files

After [installing the engine](/getting-started/), run:

```sh
bin/rails generate rails_tool_views:component review_card
```

Use a flat snake_case name of at most 64 characters, starting with a letter. The generator creates:

```text
config/rails_tool_views/components/review_card.rb
app/views/rails_tool_views/components/_review_card.html.erb
test/rails_tool_views/components/review_card_test.rb
```

The command refuses existing destinations, including with `--force`, and paths that follow a symlink outside your application. Resolve a conflict before running it again. It does not rewrite your initializer.

## Load the Registrations

Add this to your existing `config/initializers/rails_tool_views.rb`. Keep all registrations in one shared reload block:

```ruby
Rails.application.config.to_prepare do
  RailsToolViews.reset_registry!
  Dir[Rails.root.join("config/rails_tool_views/components/*.rb")].sort.each do |file|
    load file
  end
  # Register other trusted components here too.
end
```

Do not reset the registry inside individual files. A later file would remove earlier components. Configure your [scope resolver](/production/) separately so requests use the authenticated actor and tenant.

## Authorize the Component

Both generated policies return `false`. Presentation fails with `NOT_ALLOWED` until you replace the component policy. Actions remain denied until you replace their policy too. Use trusted host records to authorize `access.actor`, `access.tenant` and allowed argument values. The generated component is not exposed to an AI adapter.

The scaffold accepts a bounded `title` prop and a bounded `value` argument. Both schemas reject extra fields. The handler changes UI state only. Replace its action and policies to match your domain; the [actions guide](/actions/) explains transactions and authorization.

Once your policies allow the current scope:

```ruby
surface = RailsToolViews.present(:review_card,
  props: { title: "Review the draft" }, scope: scope)
```

Render it with `rails_tool_views_surface(surface, scope: scope)`. The Partial uses Rails escaping and the action form helper to supply the revision, replay key and source component.

## Run the Generated Test

```sh
bin/rails test test/rails_tool_views/components/review_card_test.rb
```

The test checks the initial denied presentation through the public API. It expects the shared registration block to load your definition in the test environment. If your test helper resets the registry, run the shared reload hook afterward. When you authorize the component, replace the denial test with allowed and denied actor/tenant cases, invalid arguments, and saved-state checks. Keep the generated test out of the runtime package.

For a ViewComponent, use the [registration guide](/components/); this generator creates a Partial only.

Generating a Component

Generate a Partial with closed schemas and configure host authorization before using it.

After reading this guide, you will know:

Generate the registration, Partial and test scaffold.
Load several components during Rails reloads.
Replace denied policies with host authorization.

Generate the Files

After installing the engine, run:

bin/rails generate rails_tool_views:component review_card

Use a flat snake_case name of at most 64 characters, starting with a letter. The generator creates:

config/rails_tool_views/components/review_card.rb
app/views/rails_tool_views/components/_review_card.html.erb
test/rails_tool_views/components/review_card_test.rb

The command refuses existing destinations, including with --force, and paths that follow a symlink outside your application. Resolve a conflict before running it again. It does not rewrite your initializer.

Load the Registrations

Add this to your existing config/initializers/rails_tool_views.rb. Keep all registrations in one shared reload block:

Rails.application.config.to_prepare do
  RailsToolViews.reset_registry!
  Dir[Rails.root.join("config/rails_tool_views/components/*.rb")].sort.each do |file|
    load file
  end
  # Register other trusted components here too.
end

Do not reset the registry inside individual files. A later file would remove earlier components. Configure your scope resolver separately so requests use the authenticated actor and tenant.

Authorize the Component

Both generated policies return false. Presentation fails with NOT_ALLOWED until you replace the component policy. Actions remain denied until you replace their policy too. Use trusted host records to authorize access.actor, access.tenant and allowed argument values. The generated component is not exposed to an AI adapter.

The scaffold accepts a bounded title prop and a bounded value argument. Both schemas reject extra fields. The handler changes UI state only. Replace its action and policies to match your domain; the actions guide explains transactions and authorization.

Once your policies allow the current scope:

surface = RailsToolViews.present(:review_card,
  props: { title: "Review the draft" }, scope: scope)

Render it with rails_tool_views_surface(surface, scope: scope). The Partial uses Rails escaping and the action form helper to supply the revision, replay key and source component.

Run the Generated Test

bin/rails test test/rails_tool_views/components/review_card_test.rb

For a ViewComponent, use the registration guide; this generator creates a Partial only.