access to hash through an variable in ruby on rails

Question

Hello I have following problem.

I have a hash filled with the html parameters (params):

Parameters:  "info"=>{"parameter2"=>{"r1"=>"aa", "r2"=>"bb", "r3"=>"cc", "r4"=>"dd", "r5"=>"ee"}

You can access this values like this:

<%= params[:info][:parameter2][:r1] %> --> it works fine

But I have a loop, and want to access these values through a variable like that:

<% for number_row in (1..@numb_rows) %>

<%= params[:info][:parameter2]["r" + number_row.to_s]  %>

<% end %>

--> it doesn´t work . I always get this error :

can't convert nil into String

But the "r1" does exist. Why it always says, that it can not convert nil into String.

How I can access these params with an changing variable ??

I need something like this : params[:info][:parameter2][@var]

Answer 1

Sounds very un-ruby. Try

params[:info][:parameter2].each do |key, value|

...

Answer 2

In Ruby, things with a colon in front of it are a Symbol. The error you are getting is correct, since you are referencing "r1", instead of :r1.

You need to use to_sym to make a Symbol from a String.

n = "r" + number_row.to_s
params[:info][:parameter2][n.to_sym]

Answer 3

Try this way !

<% params[:info][:parameter2].keys do |key| %>

<%= params[:info][:parameter2][key] %>

<% end %>

Answer 4

This works for me:

1.upto(@numb_rows).each do |i|
  puts params['info']['parameter2']["r#{i}"]}
end