How to use map

This time, I will introduce how to use map.

How to use

Basic form


Array variables= ["a", "b", "c"]  
Array variables.map {|Variable name|Specific processing}

categories = ["a", "b", "c"] #Array
categories.map {|category| [category.name, category.id] }  #Id to the element of the array,Give name and issue one by one

When actually using it, it is often used with select.

application_controller.rb


def set_category
  @categories = Category.all
end

= form.select :category_id, @categories.map{ |category| [category.name, category.id] }, {prompt:"Please select"}

Completion drawing

Image from Gyazo Image from Gyazo

that's all

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