Passing parameter to partial view - Rails 4/postgresql/json - ruby-on-rails

Question

I have a Deal model with a column/attribute called 'deal_info' which is a json column.
It looks like this for example
deal1.deal_info = [ { "modal_id": "4", "text1":"lorem" },
{ "modal_id": "6", "video2":"yonak" },
{ "modal_id": "9", "video2":"boom" } ]
deal2.deal_info = [ { "modal_id": "10", "text1":"lorem" },
{ "modal_id": "11", "video2":"yonak" },
{ "modal_id": "11", "image4":"boom" } ]
On my view deal.html.erb, i have:
<%= for deal_nb in 0..#deal.number_of_deals do %>
<div class="modal fade" id="myInfoModal<%= modal_nb %>" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
<!-- render the right modal type -->
<%= render "layouts/modal_type_partials/mt#{ #deal.deal_info[deal_nb]['modal_id'] }", parameter_i_want_to_pass: deal_nb %>
</div>
<% end %>
Above, as you see above, I'd like to pass for each iteration of the loop inside parameter_i_want_to_pass the number of the iteration loop (2nd iteration would be parameter_i_want_to_pass= 2 for example).
On the partial I have:
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title" id="myModalLabel">this is mt4</h4>
</div>
<div class="modal-body">
this is the text: <%= #deal.deal_info[parameter_i_want_to_pass]['text1'] %>
</div>
</div>
I get the following error:
no implicit conversion of String into Integer (on line "this is the text: <%= #deal.deal_info[parameter_i_want_to_pass]")
Actually I even tried to detect more easily the bug by just passing a set number instead of the variable 'deal_nb'
<%= render "layouts/modal_type_partials/mt#{ #deal.deal_info[deal_nb]['modal_id'] }", parameter_i_want_to_pass: 2 %>
But I still get exactly the same error.
EDIT
To help identify the problem, if I replace inside the partial view, #deal.deal_info[parameter_i_want_to_pass]['text1'] by #deal.deal_info[2]['text1'], then it works so the problem must really be that the partial view does not want to receive the number I set inside the deal.html.erb
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title" id="myModalLabel">this is mt4</h4>
</div>
<div class="modal-body">
this is the text: <%= #deal.deal_info[2]['text1'] %>
</div>
</div>
</div>
EDIT 2
Just to update the question, I managed to solve a part of the problem. i used the method to_i to transform the string in a number
So the code above now works, it pass the information (parameter_i_want_to_pass =2) to the partial view. I checked it.
<%= render "layouts/modal_type_partials/mt#{ #deal.deal_info[deal_nb]['modal_id'] }", parameter_i_want_to_pass: 2 %>
But the remaining problem, is how to not set it to 2 but to pass the number of the iteration loop
<%= for deal_nb in 0..#deal.number_of_deals do %>
<div class="modal fade" id="myInfoModal<%= modal_nb %>" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
<!-- render the right modal type -->
<%= render "layouts/modal_type_partials/mt#{ #deal.deal_info[deal_nb]['modal_id'] }", parameter_i_want_to_pass: deal_nb %>
</div>
<% end %>
Here I run into an Error
undefined local variable or method `modal_number'

Answer 1

Your variable names are a little confusing, but I think this is what you're trying to do. I am using the each_with_index method to loop through each modal inside of the deal's deal_info. Then I use the locals: { } argument for render partial: in order to pass variables to the partial. The partial then refers to these variables like they are defined locally. The partial doesn't even really end up needing the index variable, but I showed how you would pass it anyway.
View
<% #deal.deal_info.each_with_index do |modal, index| %>
<div class="modal fade" id="myInfoModal<%= index %>" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
<!-- render the right modal type -->
<%= render partial: "layouts/modal_type_partials/mt#{ modal['modal_id'] }", locals: { modal: modal, index: index } %>
</div>
<% end %>
Partial
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
<h4 class="modal-title" id="myModalLabel">this is mt4</h4>
</div>
<div class="modal-body">
this is the text: <%= modal['text1'] %>
</div>
</div>
...

Answer 2

deal1.deal_info = [ { "modal_id": "4", "text1":"lorem" },
{ "modal_id": "6", "video2":"yonak" },
{ "modal_id": "9", "video2":"boom" } ]
is not valid ruby code. You need to parse the json string:
require 'json'
deal1.deal_info = JSON.parse('[
{ "modal_id": "4", "text1":"lorem" },
{ "modal_id": "6", "video2":"yonak" },
{ "modal_id": "9", "video2":"boom" }
]')
This will convert it into an array of hashes:
[{"modal_id"=>"4", "text1"=>"lorem"}, {"modal_id"=>"6", "video2"=>"yonak"}, {"modal_id"=>"9", "video2"=>"boom"}]