<%# Bad - string interpolation %>

``` For complex cases, use `token_list` helper: ```erb

``` ## Collection Rendering Always cache, always specify `as:`: ```erb <%= render partial: 'cards/card', collection: @cards, as: :card, cached: true %> ``` ## Turbo Streams Prepend/append with update for empty states: ```erb <%# Add item and update counter/empty state %> <%= turbo_stream.before :cards, @card %> <%= turbo_stream.update :cards_count, @cards.count %> <%# Remove and handle empty %> <%= turbo_stream.remove @card %> <%= turbo_stream.update :cards_empty, partial: 'empty' if @cards.none? %> ``` ## Stimulus Integration Layer controllers on existing elements: ```erb <%# Good - multiple controllers on body %> <%# Bad - wrapper div just for controller %>

<%= render @card %>

``` Keyboard shortcuts via body controller: ```erb ``` ## Quick Reference | Pattern | Use | |---------|-----| | `local_assigns.fetch(:x, default)` | Optional locals | | `[...].compact.join(' ')` | Conditional CSS classes | | `cached: true, as: :item` | Collection rendering | | `turbo_stream.before` + `.update` | Add + refresh related | | `data-controller="a b c"` | Multiple controllers | ## Common Mistakes | Wrong | Right | |-------|-------| | `local_assigns[:x] \|\| default` | `local_assigns.fetch(:x, default)` | | Wrapper div for Stimulus | Add controller to existing element | | `render @cards` without cache | `render collection:, cached: true` | | Partial in deep nested path | Lowest common ancestor |