Ruby: How to store and display a day of the week?

I'm relatively new to Ruby. I need to keep track of a day of the week on my activity model. The code that I have so far doesn't seem like the most elegant solution. I am wondering if there is a better way.

So far, this is what I have in my form:

<%= form_for(@activity) do |f| %>
  <div class="field">
    <%= f.label :day %><br />
    <%= f.select :day, [['Sunday', 0], ['Monday', 1], ['Tuesday', 2], ['Wednesday', 3], ['Thursday', 4], ['Friday', 5], ['Saturday', 6]] %>
  </div>
<% end %>

And when I need to display the day of the week:

<% days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'] %>
<% @activities.each do |activity| %>
  <%= days[activity.day.to_i] %>
<% end %>

How can I do this better? Feel free to mention any library/gem that I may not be aware of.

Solution:

Ruby provides the Date::DAYNAMES constant which is an array of days of the week. We can reuse that in our code:

<%= form_for(@activity) do |f| %>
  <div class="field">
    <%= f.label :day %><br />
    <%= f.select :day, Date::DAYNAMES.zip((0..6开发者_如何学Python).to_a) %>
  </div>
<% end %>

<% @activities.each do |activity| %>
  <%= Date::DAYNAMES[activity.day.to_i] %>
<% end %>

---

Ruby's Date class already has a constant defined that holds the name of the days in an array: Date::DAYNAMES.

For example, you could do something like:

days = []
Date::DAYNAMES.each_with_index { |x, i| days << [x, i] }

I don't know if I'd necessarily say that this is better, but you can definitely leverage what is already available to you.

---

The easiest way (RoR) is using the built-in constant:

Date::DAYS_INTO_WEEK
# => 
{:monday=>0,
 :tuesday=>1,
 :wednesday=>2,
 :thursday=>3,
 :friday=>4,
 :saturday=>5,
 :sunday=>6}

---

In the latest versions you can define an enum with that constant and then use it for different things:

In migration, day_of_week is integer

In model:

enum :day_of_week => Date::DAYS_INTO_WEEK

And then you can use searches in model

Model.day_of_weeks.keys[0..4] will return ['monday', 'tuesday', .... 'friday']

Model.monday is equivalent to Model.where("day_of_week = ?", 'monday')

http://api.rubyonrails.org/classes/ActiveRecord/Enum.html

---

To keep it simplest, I would :

• save the plain text name of the day instead of number in @activity.day
• add a constant DAYS, it can live on your Activity model but may move to somewhere else in the future

Then it will looks like :

Model

DAYS = ['monday','tuesday',...]

validates_inclusion_of :day, :in => DAYS

View : form

<%= f.collection_select :day, Activity::DAYS, :to_s, :humanize %>

View : display

<%= activity.day.humanize %>

Keep it simple and you will extend it later if needed :)