Include blank for first item in select list in options_for_select tag

I tried :include_blank => true, but it didn'开发者_运维知识库t work.

<select>
    <%= options_for_select Model.all.collect{|mt| [mt.name, mt.id]} %>
</select>

If I need to add it to the collection, how would you do that?

I think you want this format:

select("model_name", "model_id", Model.all.collect {|mt| [ mt.name, mt.id ] }, {:include_blank => 'name of your blank prompt'})

BTW: was assuming Modle was suppose to be Model. To use using collection_select:

collection_select(:model, :model_id, Model.all, :id, :name, :prompt => true)

I believe the :include_blank options only exist for select fields tied to a model.

Assuming you want to use a plain <select> tag instead of a <%= select(...) %> tied to a model, you can insert a blank entry at the front of your results:

<%= options_for_select Modle.all.collect{|mt| [mt.name, mt.id]}.insert(0, "") %>

Since you have tagged as select-tag you can use the option include_blank with select_tag.

From the documentation:

select_tag "people", options_from_collection_for_select(@people, "id", "name"), :include_blank => true

# => <select id="people" name="people"><option value=""></option><option value="1">David</option></select>

Or you can use options_for_select:

<%= select_tag column.name, options_for_select(Model.all.collect{|mt| [mt.name, mt.id]}), :include_blank => true %>

<%= options_for_select Model.all.collect{|x| [x.name,x.id]}.unshift(["",nil]) %>

= select_tag "some_value", options_for_select(Model.all.collect{ |x| [x.name, x.id]}.prepend([t('helpers.some_name'), nil]), :selected => params[:some_value])

If you want a slick solution you can use my gem rearmed_rails which has a feature in it that safely monkey patches options_for_select and options_for_collection_select

rails g rearmed_rails:setup

Open config/initializers/rearmed_rails.rb and change the following values to true

options_for_select_include_blank: true,
options_from_collection_for_select_include_blank: true

Now whenever you need a blank included simply do the following:

<%= options_for_select(Model.all.map{|x| [x.name,x.id]}, include_blank: true) %>

You can use the following monkey patch to add the include_blank argument to options_for_select

module OptionsForSelectIncludeBlankPatch

  def options_for_select(container, selected = nil)
    if selected.is_a?(Hash)
      include_blank = selected[:include_blank] || selected['include_blank']
    end

    options = super

    if include_blank
      include_blank = '' if include_blank == true

      if Rails::VERSION::MAJOR >= 5 && Rails::VERSION::MINOR >= 1
        str = tag_builder.content_tag_string(:option, include_blank, {value: ''})
      else
        str = content_tag_string(:option, include_blank, {value: ''})
      end

      options.prepend(str)
    end

    options
  end

end

ActiveSupport.on_load(:action_view) do
  ActionView::Base.send(:include, RearmedRails::RailsHelpers)
end