Using variables in ruby erb variables

Question

I have an erb file with a lot of these and I am trying to create a loop for them:

<% if @addhostgroup -%>
  <% @addhostgroup.each do |k, v| %>
    <%= k %> <%= v %>
  <% end %>
<% end %>

<% if @addservicegroup -%>
  <% @addservicegroup.each do |k, v| %>
    <%= k %> <%= v %>
  <% end %>
<% end %>

What I want to do is something like this:

<% %w(addhostgroup addservicegroup).each do |action| %>
  <% if @action -%>
    <% @action.each do |k, v| %>
      <%= k %> <%= v %>
    <% end %>
  <% end %>
<% end %>

Can somebody tell me how to use variables on erb variables names?

I was searching for a way without success.

Thank you very much!

Please show your recipe code also, we can't guess what you give to the template resource with only this few lines — Tensibai
– Tensibai, Commented Dec 13, 2018 at 10:23
It's usually a good idea to keep templates simple / dumb / logic-less. Have you considered merging the hashes outside the template and just passing a single hash? — Stefan
– Stefan, Commented Dec 13, 2018 at 10:39

Tom · Accepted Answer · 2018-12-13 10:25:51Z

4

Edit: An easier way would be to make a normal array instead of a percent literal. [@addhostgroup, @addservicegroup].each do |action|. Sometimes I over look the little things :)

You can use instance_variable_get along with the array and iteration into action that you have setup.

Add a line immediately inside the each block with: <% instance_var_value = instance_variable_get(:"@#{action}") %>

You could also map the values into the array before iterating over it.

answered Dec 13, 2018 at 10:25

Tom

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Comments

DonPaulie · Accepted Answer · 2018-12-13 10:34:42Z

2

The problem is that block variable action holds a string with the name of the action. You want to call @variable with dynamic name based on the name. You are searching for this piece of code:

instance_variable_get("@#{action}")

edited Dec 13, 2018 at 10:34

answered Dec 13, 2018 at 10:27

DonPaulie

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4 Comments

sawa Over a year ago

The block variable action will have precedence over the method action within the block, so that would not be a problem.

DonPaulie Over a year ago

You're right, my wording fault... I'll edit my answer.

ice Over a year ago

@DonPaulie, thank you for your help. This is what I've looked for. I will accept Tom's answer because he just replied first.

DonPaulie Over a year ago

@ice I was glad to help. I know, I only did not want to delete it just because another answer appeared before I completed mine :-D

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