Saving enum from select in Rails 4.1

Question

I am using the enums in Rails 4.1 to keep track of colors of wine.

Wine.rb

class Wine < ActiveRecord::Base
    enum color: [:red, :white, :sparkling]
end

In my view, I generate a select so the user can select a wine with a certain color

f.input :color, :as => :select, :collection => Wine.colors

This generates the following HTML:

<select id="wine_color" name="wine[color]">
  <option value=""></option>
  <option value="0">red</option>
  <option value="1">white</option>
  <option value="2">sparkling</option>
</select>

However, upon submitting the form, I receive an argument error stating '1' is not a valid color. I realize this is because color must equal 1 and not "1".

Is there a way to force Rails to interpret the color as an integer rather than a string?

Solution 1

Alright, so apparently, you shouldn't send the integer value of the enum to be saved. You should send the text value of the enum.

I changed the input to be the following:

f.input :color, :as => :select, :collection => Wine.colors.keys.to_a

Which generated the following HTML:

<select id="wine_color" name="wine[color]">
  <option value=""></option>
  <option value="red">red</option>
  <option value="white">white</option>
  <option value="sparkling">sparkling</option>
</select>

Values went from "0" to "red" and now we're all set.

---

If you're using a regular ol' rails text_field it's:

f.select :color, Wine.colors.keys.to_a

---

If you want to have clean human-readable attributes you can also do:

f.select :color, Wine.colors.keys.map { |w| [w.humanize, w] }

Solution 2

No need converting the enum hash to array with to_a. This suffice:

f.select :color, Wine.colors.map { |key, value| [key.humanize, key] }

Solution 3

The accepted solution didn't work for me for the human readable, but I was able to get it to work like this:

<%= f.select(:color, Wine.colors.keys.map {|key| [key.humanize, key]}) %>

This was the cleanest, but I really needed to humanize my keys:

<%= f.select(:color, Wine.colors.keys) %>

Solution 4

I just put together an EnumHelper that I thought I'd share to help people who need more customised enum labels and locales for your enum selects.

module EnumHelper

  def options_for_enum(object, enum)
    options = enums_to_translated_options_array(object.class.name, enum.to_s)
    options_for_select(options, object.send(enum))
  end

  def enums_to_translated_options_array(klass, enum)
    klass.classify.safe_constantize.send(enum.pluralize).map {
        |key, value| [I18n.t("activerecord.enums.#{klass.underscore}.#{enum}.#{key}"), key]
    }
  end

end

In your locale:

 en:
   activerecord:
     enums:
      wine:
        color:
          red:   "Red Wine"
          white:  "White Wine"

In your views:

 <%= f.select(:color, options_for_enum(@wine, :color)) %>

Solution 5

If you use enum in Rails 4 then just call Model.enums:

f.select :color, Wine.colors.keys

To create HTML:

<select name="f[color]" id="f_color">
    <option value="red">red</option>
    <option value="white">white</option>
    <option value="sparkling"> sparkling </option>
</select>

Or add method in controller:

def update_or_create
    change_enum_to_i
    ....
end

def change_enum_to_i
    params[:f]["color"] = params[:f]["color"].to_i
end

View more solutions

Comments

[TPR]

Where did the "input" method come from? Thanks

[jakealbaugh]

FWIW, I needed to make it f.select :color, Wine.colors.to_a.map { |w| [w[0].humanize, w[0]] } because w represented an array. Not sure why, but maybe this will help someone.

[Anwar]

using titleize might be a better idea if you have two or more words

[xander-miller]

the keys method returns an array so the to_a is redundant. Alternatively the select helper method takes a 2D array for options so you can just use to_a.

[FlyingV]

What if an Invalid String is sent such as "ERROR_JUNK_Submission". Obviously there is no enum value such as this, and an exception is thrown. Where would we catch it?

[V-SHY]

rails 5 supports the cleanest way now

[ismailarilik]

@V-SHY, what is this way, can you explain?

[V-SHY]

@ismailarilik, directly provide the keys as select option, <%= f.select(:color, Wine.colors.keys) %>

[Tetsujin no Oni]

The edit makes the translation keys more readable by finding enums belonging to MultipleWordClassName under the rather more typical multiple_word_class_name rather than multiplewordclassname

[Peter P.]

How about adding in a default for a graceful fallback: [I18n.t("activerecord.enums.#{klass.underscore}.#{enum}.#{ke‌​y}", default: key.humanize), key] Also, remove the last humanize as it may distort capitalization if its multiple words

[hguzman]

The model Wine has a enum called color enum color: [:red, :white, :sparkling]so the correct sentence is f.input :color, :as => :select, :collection => Wine.color.keys.to_a