rails form for model select box with 1-dimensional data

问题

I want to limit the entry possibilities for a text field in my model to a previously defined array.

How do I make an options_for_select with just a 1-dimensional array like ["foo","bar","foobar"]?

I tried

form_for @mappings do |f|
  f.select(:mapping_type, options_for_select(["foo","bar","foobar"]), class: "..."

end

But the select box comes out all messed up like this:

<select name="section_mapping[mapping_type]" id="section_mapping_mapping_type">

as opposed to what it should be:

<select name="mapping_type" >

EDIT:

I changed the f.select to select_tag and the form shows up without any errors but when I submit it, it leaves that field empty

EDIT 2:

f.collection_select(:mapping_type, options_for_select([...]), class: "..."

works as in it submits the form with the value correctly, but the HTML class is not applied. Why is that?

回答1:

Basically, you want to be able to tie your collection select to a property of the object (in your case, @mappings)

Also, from the doc on rails collection_select, it will take options as follow:

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

• Objet: the object you are binding the selected option to (@mappings [f]) in this case
• method: The property/attribute of the object (in this case, mapping_type)
• collection: The collection for select ( ["foo","bar","foobar"] )
• value_method: The value you want to send back with the submit (Note that this is a method which means you should be able to call it on an object.) more on this later.
• text_method: The value you want to show as text on the select option on the view (this is also a method as above, more on this later as well)
• options: any additional option you want, (e.g: include_blank)
• html_options: eg: id, class etc.

As concerning the value_method and text_method, these are methods that should be called on your collection, which means that your collection will be an array of objects.

To this end, you can have the following:

class CollectionArr
  include ActiveModel::Model

  attr_accessor :name
  ARR = [
    {"name" => "foo"},
    {"name" => "bar"},
    {"name" => "foobar"}
  ]

  def self.get_collection
    ARR.collect do |hash|
      self.new(
        name: hash['name']
      )
    end
  end
end

From here, calling CollectionArr.get_collection will return an array of objects where you can cal .name to return either foo, bar, or foobar. This makes using the collection_select and easy deal from here:

<%= f.collection_select : mapping_type, CollectionArr.get_collection, :name, :name, {:include_blank => "Select one"} %>

And all is green...

来源：https://stackoverflow.com/questions/33880045/rails-form-for-model-select-box-with-1-dimensional-data