Include blank for first item in select list in options_for_select tag

问题

I tried :include_blank => true, but it didn'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?

回答1:

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)

回答2:

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, "") %>

回答3:

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 %>

回答4:

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

回答5:

= 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])

回答6:

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) %>

来源：https://stackoverflow.com/questions/6710965/include-blank-for-first-item-in-select-list-in-options-for-select-tag