How to pass javascript variable to rails partial view

Question

I got a situation, there is a Javascript variable I need pass to rails partial view.

For example in test.html.erb

<script type="text/javascript">
var array  =  <%= raw sort_section %>
    for(i = 0; i < array.length; i++) {
        $('#test').append("<%= j render :partial => 'section_in_panel', :locals => {:section => raw array[i]} %>");
    }
</script>

But it keep throwing syntax error, I have try many ways like

{:section => j sort_section_js[i]} %>"
{:section =>" + sort_section_js[i] + "}%>"

I need to use that because I want to call ajax to change array dynamically.

Update

So, maybe I need to write a controller

def get_new_variable
    ...
    return new_variable
end

Then in the test.html.erb

<script>
$('test').onclick(function(event) {
   //write some ajax call
   //get new_variable
   $('#test').empty();
   $('#test').append("<%= j render :partial => 'section_in_panel', :locals => {:section => raw new_variable} %>");
  });
)</script>

Is that right direction?

It hold a nested array, sorry I forgot to change the variable name. — rj487
– rj487, Commented Aug 26, 2016 at 7:08
Javascript is run on the client after ruby renders the view on the server, then you can't pass the value of javascript variable to rails partial view. — Alberto Juan
– Alberto Juan, Commented Aug 26, 2016 at 7:14
I get it, so the only way is to write a new controller to get new variable, and then pass the new variable to partial view? — rj487
– rj487, Commented Aug 26, 2016 at 7:18

XavM · Accepted Answer · 2016-08-26 07:43:20Z

1

As Alberto Juan wrote in comment, you can't use javascript variable in ruby code. Ruby code will be interpreted before javascript and will not know what is the i.

Update: Your update will not work either as your using new_variable you get in your javascript code.

For using partial after ajax call, follow instructions in this link

Example:

items/index.html.erb

<div class="grid">
  <% @categories.each do |cat| %>
    <%= link_to cat.name, fetch_items_path(:cat_id => cat.id), :remote => true %>
  <% end %>

  <%= render partial: 'item_grid', locals: { items: @items} %>
</div>

routes.rb

get "/fetch_items" => 'items#from_category', as: 'fetch_items'

items_controller.rb

def index
    @items = Item.all
    @categories = Category.all
end

def from_category
    @selected = Item.where(:category_id => params[:cat_id])
    respond_to do |format|
        format.js
    end
end

views/items/from_category.js.erb

$("#items_grid").html("<%= escape_javascript(render partial: 'items_list', locals: { items: @selected } ) %>");

edited Aug 26, 2016 at 7:43

answered Aug 26, 2016 at 7:34

XavM

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1 Comment

rj487 Over a year ago

Great practice! After I did this tiny practice, I got the right direction to finish my project. Thanks!

Sergio Tulentsev · Accepted Answer · 2016-08-26 08:02:41Z

0

You can use gem gon or simply do something like this:

<script>
  MyVars[:someVar] = <%= some_value %>;
</script>

But, I recommend you to separate your backend an frontend code and use JSON for passing data to JS.

edited Aug 26, 2016 at 8:02

Sergio Tulentsev

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answered Aug 26, 2016 at 7:57

egoholic

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2 Comments

Sergio Tulentsev Over a year ago

But it's the other direction. They want to pass data from JS.

egoholic Over a year ago

Yep. It's my fail.

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