Add error_key field option. Closes #318 (v3)

README.md

@@ -264,6 +264,19 @@ Our select helper accepts the same arguments as the [default Rails helper](http:
 <%= f.select :product, [[1, "Apple"], [2, "Grape"]], { label: "Choose your favorite fruit:" }, { class: "selectpicker" } %>
 ```
 
+#### Collection select on an association
+
+Validations on foreign key columns used for assigning associations do not by
+default know about validation errors on the association itself. This can be
+changed by using the `error_key` option, which will look for errors using the
+given key rather than the value being assigned to by the select:
+
+```erb
+<%= bootstrap_form_for(@user) do |f| %>
+  <%= f.collection_select(:product_id, Product.all, :id, :name, error_key: :product) %>
+<% end %>
+```
+
 ### Checkboxes and Radios
 
 Checkboxes and radios should be placed inside of a `form_group` to render

lib/bootstrap_form/form_builder.rb

@@ -196,15 +196,16 @@ def radio_buttons_collection(*args)
     def form_group(*args, &block)
       options = args.extract_options!
       name = args.first
+      error_name = options.delete(:error_key) || name
 
       options[:class] = ["form-group", options[:class]].compact.join(' ')
-      options[:class] << " #{error_class}" if has_error?(name)
+      options[:class] << " #{error_class}" if has_error?(error_name)
       options[:class] << " #{feedback_class}" if options[:icon]
 
       content_tag(:div, options.except(:id, :label, :help, :icon, :label_col, :control_col, :layout)) do
-        label = generate_label(options[:id], name, options[:label], options[:label_col], options[:layout]) if options[:label]
+        label = generate_label(options[:id], name, error_name, options[:label], options[:label_col], options[:layout]) if options[:label]
         control = capture(&block).to_s
-        control.concat(generate_help(name, options[:help]).to_s)
+        control.concat(generate_help(error_name, options[:help]).to_s)
         control.concat(generate_icon(options[:icon])) if options[:icon]
 
         if get_group_layout(options[:layout]) == :horizontal
@@ -322,13 +323,15 @@ def form_group_builder(method, options, html_options = nil)
       icon = options.delete(:icon)
       label_col = options.delete(:label_col)
       control_col = options.delete(:control_col)
+      error_key = options.delete(:error_key)
       layout = get_group_layout(options.delete(:layout))
       form_group_options = {
         id: options[:id],
         help: help,
         icon: icon,
         label_col: label_col,
         control_col: control_col,
+        error_key: error_key,
         layout: layout,
         class: wrapper_class
       }
@@ -368,19 +371,19 @@ def convert_form_tag_options(method, options = {})
       options
     end
 
-    def generate_label(id, name, options, custom_label_col, group_layout)
+    def generate_label(id, name, error_name, options, custom_label_col, group_layout)
       options[:for] = id if acts_like_form_tag
       classes = [options[:class], label_class]
       classes << (custom_label_col || label_col) if get_group_layout(group_layout) == :horizontal
       unless options.delete(:skip_required)
-        classes << "required" if required_attribute?(object, name)
+        classes << "required" if required_attribute?(object, error_name)
       end
 
       options[:class] = classes.compact.join(" ")
 
-      if label_errors && has_error?(name)
-        error_messages = get_error_messages(name)
-        label_text = (options[:text] || object.class.human_attribute_name(name)).to_s.concat(" #{error_messages}")
+      if label_errors && has_error?(error_name)
+        error_messages = get_error_messages(error_name)
+        label_text = (options[:text] || object.class.human_attribute_name(error_name)).to_s.concat(" #{error_messages}")
         label(name, label_text, options.except(:text))
       else
         label(name, options[:text], options.except(:text))

test/bootstrap_selects_test.rb

@@ -157,4 +157,12 @@ def setup
       assert_equivalent_xml expected, @builder.datetime_select(:misc, { include_blank: true }, class: "my-datetime-select")
     end
   end
+
+  test "collection_selects display errors correctly when error_key is set" do
+    @address = Address.new
+    @address.valid?
+
+    expected = %{<form accept-charset=\"UTF-8\" action=\"/addresses\" class=\"new_address\" id=\"new_address\" method=\"post\" role=\"form\"><div style=\"margin:0;padding:0;display:inline\"><input name=\"utf8\" type=\"hidden\" value=\"&#x2713;\" /></div><div class=\"form-group has-error\"><label class=\"control-label required\" for=\"address_user_id\">User can&#39;t be blank</label><select class=\"form-control\" id=\"address_user_id\" name=\"address[user_id]\"></select><span class=\"help-block\">can&#39;t be blank</span></div></form>}
+    assert_equivalent_xml expected, bootstrap_form_for(@address, url: "/addresses", label_errors: true, inline_errors: true) { |f| f.collection_select :user_id, [], :id, :email, error_key: :user }
+  end
 end

test/dummy/app/models/address.rb

@@ -1,3 +1,4 @@
 class Address < ActiveRecord::Base
   belongs_to :user
+  validates :user, presence: true
 end