Rails: Preselect a value in ActionView-Helper 'collection_select'

actionview, actionviewhelper, ruby-on-rails

Solution

From the docs:

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

collection_select(:post, :author_id, Author.all, :id, :name_with_initial)

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>

So you just need to make sure that `@my_object.my_method` returns a value that matches one of the available option values. If there's a match then that option will be selected.

Problem

I'm trying to get the ActionView-Helper `collection_select` to take a value that will be preselected in the dropdown-menu. Neither (`:selected` in the html-option-hash) ``` <%= collection_select(:my_object, :my_method, @my_collection, :id, :description_string, {}, {:selected => @my_collection_object.id}) %> ``` nor (`:selected` in the option-hash) ``` <%= collection_select(:my_object, :my_method, @my_collection, :id, :description_string, {:selected => @my_collection_object.id}, {}) %> ``` seem to work. What am I doing wrong? Can anyone help me on this one?

Original source