Helper method renders no list items

Question

In Rails 7, why the following helper doesn't render the list items?

def list(options)
  tag.ul(class: "a") do
    options.each do |option|
      tag.li(class: "b") do
        tag.span(option, class: "c")
      end
    end
  end
end

I call <%= list(["X", "Y", "Z"]) %> and what is rendered is simply <ul class="a"></ul>.

What am I missing here?

Answer 1

Normally, with erb you'd write this:

<%= tag.ul(class: "a") do %>
  <% ["X", "Y", "Z"].each do |option| %>
    <%= tag.li(class: "b") do %>         # <%= %> is the same as `concat`
      <%= tag.span(option, class: "c") %>
    <% end %>
  <% end %>
<% end %>

Using concat:

def list(options)
  tag.ul(class: "a") do
    options.each do |option|
      concat(
        tag.li(class: "b") do
          # concat could be omitted here for a single tag
          concat tag.span(option, class: "c")
        end
      )
    end
  end
end

Using safe_join:

def list(options)
  tag.ul(class: "a") do
    safe_join(
      options.map do |option|
        tag.li(class: "b") do
          tag.span(option, class: "c")
        end
      end
    )
  end
end