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POrails instance variable not working in the template
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  1. POrails instance variable not working in the template
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    copied!<p>Not able to understand why the same command <code>Category.find(:all , :order =&gt; 'name ASC')</code> works in the rails console but not returning anything in the template and controller please help</p> <p><code>_form.html.erb</code></p> <pre><code>&lt;% @all_categories.each do |cat| -%&gt; &lt;li&gt;&lt;%= check_box_tag('categories[]' , cat.id , @post.categories.collect{|c| c.id}.include?(cat.id))%&gt; &lt;%= cat.name %&gt;&lt;/li&gt; &lt;% end -%&gt; </code></pre> <p><code>posts_controller.rb</code></p> <pre><code>@all_categories = Category.find(:all , :order =&gt; 'name ASC') </code></pre> <h3>rails console</h3> <pre><code>@all_categories = Category.find(:all , :order =&gt; 'name ASC') Category Load (0.2ms) SELECT `categories`.* FROM `categories` ORDER BY name ASC =&gt; [#&lt;Category id: 1, name: "General", short_name: "general", description: "This is a general category"&gt;] </code></pre> <h3>error</h3> <pre><code>undefined method `each' for nil:NilClass </code></pre> <h1>posts_controller</h1> <pre><code> def edit @user_list = get_user_list @post = Post.find(params[:id]) end def update post_params = params[:post] author_id = post_params.delete(:author_id) #@all_categories = get_all_categories @all_categories = Category.find(:all , :order =&gt; 'name ASC') checked_categories = get_categories_from(params[:categories]) removed_categories = @all_categories - checked_categories @post = Post.find(params[:id]) @post.author = User.find(author_id) if @post.author_id != author_id if @post.update_attributes(post_params) perform_operation_on_categories flash[:notice] = "Post was successfully updated." redirect_to :action =&gt; 'show' , :id =&gt; @post else @user_list = get_user_list render :action =&gt; 'edit' end end </code></pre> <h1>index view</h1> <pre><code>&lt;h1&gt;&lt;% @page_title = 'Listing posts' %&gt;&lt;/h1&gt; &lt;%= content_tag('p',link_to('&amp;laquo Back', :controller =&gt; 'staff',:action =&gt;'menu')) %&gt; &lt;table&gt; &lt;tr&gt; &lt;th&gt;Created at&lt;/th&gt; &lt;th&gt;Title&lt;/th&gt; &lt;th&gt;Author&lt;/th&gt; &lt;th&gt;Categories&lt;/th&gt; &lt;th&gt;Status&lt;/th&gt; &lt;th&gt;Comments&lt;/th&gt; &lt;/tr&gt; &lt;% @posts.each do |post| %&gt; &lt;tr class="&lt;%= cycle('row1','row2') %&gt;"&gt; &lt;td&gt;&lt;%= post.created_at.strftime('%m/%d/%y %I:%m %p')%&gt;&lt;/td&gt; &lt;td&gt;&lt;%= h(post.title)%&gt;&lt;/td&gt; &lt;td&gt;&lt;%= h(post.author.display_name) if post.author%&gt;&lt;/td&gt; &lt;td&gt;&lt;%= post.categories.collect {|cat| cat.name}.join(", ")%&gt;&lt;/td&gt; &lt;td&gt;&lt;%= h(post.status)%&gt;&lt;/td&gt; &lt;td&gt;&lt;%= post.comments_count %&gt;&lt;/td&gt; &lt;td&gt;&lt;%= link_to('Preview',{:action =&gt;'show',:id=&gt;post,:target =&gt; '_blank'})%&gt;&lt;/td&gt; &lt;td&gt;&lt;%= link_to 'Edit', edit_post_path(post) %&gt;&lt;/td&gt; &lt;td&gt;&lt;%= link_to 'Delete', post, :method =&gt; :delete, :data =&gt; { :confirm =&gt; 'Are you sure you want to permanently remove this post?' } %&gt;&lt;/td&gt; &lt;/tr&gt; &lt;% end %&gt; &lt;/table&gt; &lt;%= will_paginate(@posts) %&gt; &lt;br/&gt; &lt;%= link_to 'New Post' , :action=&gt; 'new' %&gt; </code></pre> <h1>_form.html.erb (the part where i am getting error)</h1> <pre><code>&lt;table&gt; &lt;tr&gt; &lt;th&gt;Title&lt;/th&gt; &lt;td&gt;&lt;%= text_field(:post,:title,:size =&gt; 40 , :style =&gt; "font-size: 1.5em;")%&gt;&lt;/td&gt; &lt;td rowspan="2"&gt; &lt;div class="categorylist"&gt; &lt;h2&gt;Categories:&lt;/h2&gt; &lt;ul&gt; &lt;% @all_categories.each do |cat| -%&gt; &lt;li&gt;&lt;%= check_box_tag('categories[]' , cat.id , @post.categories.collect{|c| c.id}.include?(cat.id))%&gt; &lt;%= cat.name %&gt;&lt;/li&gt; &lt;% end -%&gt; &lt;/ul&gt; </code></pre> <h1>edit.html.erb</h1> <pre><code>&lt;% @page_title = 'Edit Post' -%&gt; &lt;%= content_tag('p',link_to('&amp;laquo; Back', :action =&gt; 'index'))%&gt; &lt;%= form_tag(:action =&gt; 'update') do -%&gt; &lt;%= render(:partial =&gt; 'form')%&gt; &lt;%= submit_tag('Create', :style =&gt; 'margin: 1.5em 0 0 100px;')%&gt; &lt;% end %&gt; &lt;%= link_to('Preview Post' , {:action=&gt;'show',:id =&gt; @post} ,:target =&gt; '_blank')%&gt; </code></pre>
 

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