Ruby on rails- How can I insert a variable into a string in array?

Question

I want to make a repetition using: for.

For example,

<li class="<%= is_active?([y17s_index_path,y17s_gun_path]) %>"><a href='<%= y17s_index_path%>'>2017</a></li>
<li class="<%= is_active?([y16s_index_path,y16s_gun_path]) %>"><a href='<%= y16s_index_path%>'>2016</a></li>
<li class="<%= is_active?([y15s_index_path,y15s_gun_path]) %>"><a href='<%= y15s_index_path%>'>2015</a></li>
<li class="<%= is_active?([y14s_index_path,y14s_gun_path]) %>"><a href='<%= y14s_index_path%>'>2014</a></li>
.
.
.

How can I write repetitive statement in this case? I tried #{} but It does not work.

I want to change only 17,16,15... these numbers.

I'm sorry, not a string but a path.

Sieun Sim
– Sieun Sim

2017-12-03 15:06:40 +00:00
Commented Dec 3, 2017 at 15:06 — Sieun Sim
– Sieun Sim, Commented Dec 3, 2017 at 15:06

Frederik Spang · Accepted Answer · 2017-12-03 17:42:30Z

2

You can use some light meta-programming with the send-method with an each-call:

<% [1..17].each do |i| %>
  <li class="<%= is_active?([send("y#{i}s_index_path"), send("y#{i}s_gun_path")]) %>"><a href='<%= send("y#{i}s_index_path") %>'>20<%= "%02d" % i %></a></li>
<% end %>

Should output 2001 to 2017, with same methods as before. You can see the documentation on send method here: https://apidock.com/ruby/Object/send

answered Dec 3, 2017 at 17:42

Frederik Spang

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2 Comments

Sieun Sim Over a year ago

Thank you a lot. I cannot understand 100% what "send" do exactly, but the problem is solved!

Frederik Spang Over a year ago

What Send does, basically, is to call a method. It simply calls the method that has the name of the first argument

allknowingfrog · Accepted Answer · 2017-12-03 17:50:17Z

1

I believe send() will do what you need here, as Frederik Spang suggests. I would just add that "dynamic access" is the common term for what you're describing. Having a name for the concept will help a lot if you want to search for more information, i.e. try searching for "dynamically access Ruby methods".

answered Dec 3, 2017 at 17:50

allknowingfrog

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1 Comment

Sieun Sim Over a year ago

You're right. It's always difficult for me to search programmatic problems in English. From now on, I will try to translate the name of concept first as your advise. Thanks a lot!!

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