In Ruby on Rails 3.2.3, I researched how to format time and set initial values in input forms, so here’s a memo.

Excerpt from the form. Write it like this:

# app/views/articles/_article_form.html.haml
  %tr
    %th Published Time
    %td
      = f.text_field :published_at, value: (f.object.published_at.blank? ? '' : f.object.published_at.strftime('%Y/%m/%d %H:%M')

That’s all from the Gemba.

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Reference Information

・Reverse Lookup Ruby - Date and Time

・Format DateTime in Text Box in Rails - Stack Overflow