layouts-and-rendering

Rails partials should explicitly pass local variables to avoid coupling with controller instance variables. This practice ensures partials remain reusable, independent components that receive data directly through the render call.

The difference between render and redirect_to in Rails is that render generates a response from a template within the same request, while redirect_to triggers a new HTTP request. Using both in one action causes a double render error.

For Turbo and Hotwire form submissions in Rails, you need a 303 status code for successful redirects and a 422 status code for validation errors. These status codes ensure Turbo correctly processes form re-rendering and navigation.

You use content_for and yield for nested layouts in Rails views by defining content blocks in child templates and capturing them with provide. This mechanism allows parent layouts to insert specific content into designated sections.

The best way to optimize rendering collections in Rails is to use collection rendering with partials. This approach automatically iterates through records and renders a partial for each item, reducing template code and improving performance.

A double render error in a Rails controller action occurs when you call render or redirect_to multiple times in a single request cycle. You must ensure only one rendering instruction is executed per action flow.