Rails 3, passing local variable to partial [duplic

问题:

Possible Duplicate:
Rails: confused about syntax for passing locals to partials

I want to pass local variable(which doesn't have relevant field in model) to partial.

# infos/index.html.erb

<%= render :partial => 'info', :locals => {:info => first, :img_style => "original"} %> 

:img_style will be html style for image.

# infos/_info.html.erb
<% first = @infos.shift %>
<%= image_tag(info.image.url, :class => img_style),  info %> 
# and here goes code for normal iteration
<% @infos.each do |e| %>
# etc

But it does not work, it returns error:

# GET /infos/
undefined local variable or method `img_style' for #<#<Class:0xc471f34>:0xc470cc4>

It can be done without making redundant partials?

Sorry for my English. :P

EDIT:

Well model Info don't have :img_style field

# db/schema.rb
  create_table "infos", :force => true do |t|
    t.string   "title"
    t.text     "description"
    t.integer  "place_id"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "image_file_name"
    t.string   "image_content_type"
    t.integer  "image_file_size"
    t.datetime "image_updated_at"
    t.text     "short"
  end

EDIT2:

Even simple

<%= img_style %>

don't works.

Application Stack Trace

app/views/infos/_info.html.erb:3:in `_app_views_infos__info_html_erb___1029249744_92158380_1472718'
app/views/infos/index.html.erb:7:in `_app_views_infos_index_html_erb__184644561_92172050_0'
app/controllers/infos_controller.rb:8:in `index'

EDIT3:

Views

# infos/index.html.erb
<div >
  <h1><%= t('info.infos') %></h1>
  <div id="left">
    <% first = @infos.shift %>
    <div>
      <% @aimg_style = "original"%>
      <%= render 'info', :locals => {@img_style => @aimg_style } %>
    </div>
    <ul>
      <% @infos.each do |e| %>
        <li>
          <div>
            <%= render :partial => 'info', :object => e %>
          </div>
        </li>
      <% end %>
    </ul>
    <%= will_paginate @infos %>

---

# infos/_info.html.erb
<%#= link_to thumbnail(info, "listTabsImg", false, img_style), info %>
  <%#= image_tag(info.image.url()) %>
  <%= img_style %>
<p>
  <strong class="nameBox"><%= link_to info.title, info %></strong>
  <span><%= info.short %>...</span>
  <%= link_to "#{t('more')} »", info %>
</p>

FINALLY

This don't works:

# infos/index.html.erb
<% first = @infos.shift %>
<div class="boxEvent">
  <% @aimg_style = "original"%>
  <%= first %>
  <%= render 'info', :locals => {:info => first, :img_style => @aimg_style } %>
</div>

This works:

# infos/index.html.erb
  <% @infos.each do |e| %>
    <li>
      <div class="boxEvent">
        <%= render :partial => 'info', :locals => {:info => e, :img_style => "original"} %>
      </div>
    </li>
  <% end %>

Anybody know why?

回答1:

I actually just use this syntax in Rails 3:

render "a_partial", :a_local_variable => whatever, :another_variable => another

回答2:

This should work:

<%= render :partial => "info", :locals => { :img_style => "original" } %>

With this partial:

# infos/_info.html.erb
<%= image_tag(info.image.url, :class => img_style),  info %>

However if you are calling the partial wrong then try this as the partial:

# infos/_info.html.erb
<%= image_tag(info.image.url(img_style)),  info %>

回答3:

I've spent several hours on this; in a view, render :partial => ? , :locals => (....} it seems if you first call:

render :partial => ? without a locals hash

and THEN call render :partial => ? with a locals hash the locals hash IS NOT passed to the view.

If the first call includes a locals hash with the same variables set to '' then the second call with REAL values will work.

回答4:

Your code (the one you have shown in the first line) should work. There is no error. I have even tested it myself and it works for me.

The usual reasons for such errors are:

• misspelled variable name
• calling the partial also from some other place, where you do not pass a :local.

The fact that your model does not have the attribute "img_style" is not important.

I can see that in your infos/index.html.erb you have two places where you call render :partial => 'info', :object => ... and you do not have :locals here. Just the line numbers do not match with the stacktrace you have posted earlier, so it's hard to say which call causes the problem.

I guess both calls to the render method need corrections.

In the first one, be specific, and call render :partial => "info" instead of render "info". This may be a bug in Rails, but for some strange reason, :locals seem to not be passed to the view in this case.

In the second call to render just add the :locals.

回答5:

I believe the problem is the trailing , info call. It is looking in the info object for img_style. You don't need it.

I love using partials but recently have seen the beauty in helper methods too, especially in simple renderings like this one.

def info_image(info, class_name="original")
   image_tag(info.image.url, :class => class_name)
end

then just

<%= info_image(first) %>

or

<%= info_image(first, "anotherclass") %>

in the view. Much cleaner.

If ever it becomes more complex. You'll only have to change code in one place.