collection 下拉默认空白值

Question

如何在 select 字段中添加默认空白值（amber 框架）？

== select_field(名称: "parent_category_id", collection: Category.all.map{|类别| [category.id, category.name]} , selected: "", class: "form-control")

Answer 1

利用 Crystal 数组可以连接的事实：

c = [["", "blank"]] + Category.all.map{|category| [category.id, category.name]}
select_field(
  name: "parent_category_id", 
  collection: c, 
  selected: "", 
  class: "form-control"
)

collection 下拉默认空白值

collection dropdown default blank value

crystal-lang

amber-framework