Support translations for ActiveRecord models

Problem:

Developers are unable to display their ActiveRecord classes in the UI
by any other name than the titleized class name.

For example,
if a team is building an admin dashboard that will be used in Russian,
they may have ActiveRecord models with English names, that need to be
translated before they're displayed in the UI.

Solution:

Rails has support for [translating ActiveRecord Models][1],
which relies on defining I18n translations
under the `activerecord.models` namespace.

Rails expects translations in the form:

```yaml
en:
  activerecord:
    models:
      user:
        one: Customer
        other: Customers
```

The separate `one` and `other` keys allow Rails to display
the correct plural or singular form of the word,
depending on the context.

We've used Rails' built-in `Foo.model_name.human` method
to correctly pull the translations out of I18n,
with sane fallbacks if the translation is not defined.

[1]: http://guides.rubyonrails.org/i18n.html#translations-for-active-record-models

CHANGELOG.md

@@ -20,6 +20,7 @@
 
 * [#251] [FEATURE] Raise a helpful error when an attribute is missing from
   `ATTRIBUTE_TYPES`
+* [#298] [FEATURE] Support ActiveRecord model I18n translations
 * [#231] [UI] Fix layout issue on show page where a long label next to an empty
   value would cause following fields on the page to be mis-aligned.
 * [#259] [BUGFIX] Make installation generator more robust

app/helpers/administrate/application_helper.rb

@@ -4,5 +4,17 @@ def render_field(field, locals = {})
       locals.merge!(field: field)
       render locals: locals, partial: field.to_partial_path
     end
+
+    def display_resource_name(resource_name)
+      resource_name.
+        to_s.
+        classify.
+        constantize.
+        model_name.
+        human(
+          count: 0,
+          default: resource_name.to_s.pluralize.titleize,
+        )
+    end
   end
 end

app/views/administrate/application/_sidebar.html.erb

@@ -11,7 +11,7 @@ as defined by the DashboardManifest.
   <% DashboardManifest::DASHBOARDS.each do |resource| %>
     <li>
       <%= link_to(
-        resource.to_s.titleize,
+        display_resource_name(resource),
         [Administrate::NAMESPACE, resource],
         class: "sidebar__link sidebar__link--#{nav_link_state(resource)}"
       ) %>

app/views/administrate/application/index.html.erb

@@ -21,7 +21,9 @@ It renders the `_table` partial to display details about the resources.
 [1]: http://www.rubydoc.info/gems/administrate/Administrate/Page/Table
 %>
 
-<% content_for(:title) { page.resource_name.pluralize.titleize } %>
+<% content_for(:title) do %>
+  <%= display_resource_name(page.resource_name) %>
+<% end %>
 
 <% content_for(:search) do %>
   <form class="search">

spec/features/sidebar_spec.rb

@@ -8,4 +8,25 @@
 
     expect(active_link.text).to eq "Customers"
   end
+
+  it "displays translated name of model" do
+    translations = {
+      activerecord: {
+        models: {
+          customer: {
+            one: "User",
+            other: "Users",
+          },
+        },
+      },
+    }
+
+    with_translations(:en, translations) do
+      visit admin_customers_path
+
+      sidebar = find(".sidebar__list")
+      expect(sidebar).to have_link("Users")
+      expect(page).to have_header("Users")
+    end
+  end
 end

spec/helpers/administrate/application_helper_spec.rb

@@ -0,0 +1,44 @@
+require "rails_helper"
+
+RSpec.describe Administrate::ApplicationHelper do
+  describe "#display_resource_name" do
+    it "defaults to the plural of the model name" do
+      displayed = display_resource_name(:customer)
+
+      expect(displayed).to eq("Customers")
+    end
+
+    it "handles string arguments" do
+      displayed = display_resource_name("customer")
+
+      expect(displayed).to eq("Customers")
+    end
+
+    it "handles plural arguments" do
+      displayed = display_resource_name(:customers)
+
+      expect(displayed).to eq("Customers")
+    end
+
+    context "when translations are defined" do
+      it "uses the plural of the defined translation" do
+        translations = {
+          activerecord: {
+            models: {
+              customer: {
+                one: "User",
+                other: "Users",
+              },
+            },
+          },
+        }
+
+        with_translations(:en, translations) do
+          displayed = display_resource_name(:customer)
+
+          expect(displayed).to eq("Users")
+        end
+      end
+    end
+  end
+end

spec/support/i18n.rb

@@ -1,3 +1,14 @@
 RSpec.configure do |config|
   config.include AbstractController::Translation
+
+  def with_translations(locale, translations)
+    original_backend = I18n.backend
+
+    I18n.backend = I18n::Backend::KeyValue.new({}, true)
+    I18n.backend.store_translations(locale, translations)
+
+    yield
+  ensure
+    I18n.backend = original_backend
+  end
 end