collection_select(object, method, collection, value_method, text_method, options = {}, html_options = {}) public

Returns <select> and <option> tags for the collection of existing return values of method for object's class. The value returned from calling method on the instance object will be selected. If calling method returns nil, no selection is made without including :prompt or :include_blank in the options hash.

The :value_method and :text_method parameters are methods to be called on each member of collection. The return values are used as the value attribute and contents of each <option> tag, respectively.

Example object structure for use with this method: 

  class Post < ActiveRecord::Base
    belongs_to :author
  end
  class Author < ActiveRecord::Base
    has_many :posts
    def name_with_initial
      "#{first_name.first}. #{last_name}"
    end
  end

Sample usage (selecting the associated Author for an instance of Post, @post): 

  collection_select(:post, :author_id, Author.all, :id, :name_with_initial, :prompt => true)

If @post.author_id is already 1, this would return: 

  <select name="post[author_id]">
    <option value="">Please select</option>
    <option value="1" selected="selected">D. Heinemeier Hansson</option>
    <option value="2">D. Thomas</option>
    <option value="3">M. Clark</option>
  </select>
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August 26, 2008
11 thanks

Customizing prompt

The :prompt option not only accepts a boolean value. It can also be given a string to define another than the standard prompt ‘Please select’. Referring to the example it could read:

collection_select(:post, :author_id, Author.find(:all),
                  :id, :name_with_initial,
                 {:prompt => 'Please select the author of this post'})
October 10, 2008
2 thanks

Make an action onchange

collection_select(nil, :provincia_id, @provincias, :id, :nombre, {:prompt => “Seleccione una provincia”}, {:onchange => “#{remote_function(:url => {:controller => ‘direccions’, :action => ”update_pueblos“}, :with => ”‘provincia_id=’+value“)}”})

June 29, 2009
2 thanks

:selected

If you want some object to be selected by default, be sure to use its id, not the whole object.

 collection_select(:post, :author_id, Author.all, :id, :name_with_initial, {:selected => current_book.authors.map(&:id)})
#=> :selected => [1,2,3,4]

and not

collection_select(:post, :author_id, Author.all, :id, :name_with_initial, {:selected => current_book.authors})
March 17, 2009
0 thanks

Post =form post, NOT the http POST method

Post =forum post, NOT the http POST method

Note: any “Post” on this page has nothing to do with http methods. When I just looked at the collection_select code I was thrown off.

January 9, 2014 - (v3.2.13)
0 thanks

onChange Event

Hello,

I’m brand new to ROR and in general server side programing. I’m a iOS developer who is trying to learn ROR.

I’m trying to use collection select to implement filtering for my page. The idea is there are a bunch of posts and I want to implement record filtering for those.

The first collection box would have parameters like “Date”, “Amount”, “Category” and based on the selection of this a secondary drop down would appear and allow the user to make a selection. The records on this page would be then filtered based on both the selection.

I have been trying out many things and have googled a lot on collection but I have reached a dead end now. I’m pretty new and just started learning ROR.

You help is much appreciated here.

Thanks in advance.

Note: the code below might be wrong and as of now its not even compiling.. currently it complaints of “remote_function” not defined…

I have a page that looks like this,

<div class=“span8”>

<% if @user.spendings.any? %>

    <h3> Spendings (<%= @user.spendings.count  %>)</h3>

    <%= collection_select(:category, :category, Category.all, :id, :name, 

{:prompt => 'Select'})%>

<%= collection_select :event, :filterType, Filters.all, :id, :filterType, {},

  {

  :onchange => remote_function(

    :url => {:action => "updatelevel", :controller => "Spendings", :id => 1},

    :with => "'level_id='+this.value"

  )}

%>

      <ol class="spendings">

        <%= render @spendings %>

      </ol>

      <%= will_paginate @spendings %>

  <% end %>

</div>