Add :include_blank option to Field::Select

- copy/pasted pretty directly from Field::BelongsTo

app/views/fields/select/_form.html.erb

@@ -27,7 +27,8 @@ to be displayed on a resource's edit form page.
         :last,
         :first,
         field.data,
-      )
+      ),
+      include_blank: field.include_blank_option
     ) %>
   <% else %>
     <%= f.select(
@@ -37,7 +38,8 @@ to be displayed on a resource's edit form page.
         :to_s,
         :to_s,
         field.data,
-      )
+      ),
+      include_blank: field.include_blank_option
     ) %>
   <% end %>
 </div>

docs/customizing_dashboards.md

@@ -223,6 +223,9 @@ an array or an object responding to `:call`. Defaults to `[]`.
 `:searchable` - Specify if the attribute should be considered when searching.
 Default is `true`.
 
+`:include_blank` - Specifies if the select element to be rendered should include
+blank option. Default is `true`.
+
 **Field::String**
 
 `:searchable` - Specify if the attribute should be considered when searching.

lib/administrate/field/select.rb

@@ -11,6 +11,10 @@ def selectable_options
         collection
       end
 
+      def include_blank_option
+        options.fetch(:include_blank, true)
+      end
+
       private
 
       def collection

spec/administrate/views/fields/select/_edit_spec.rb

@@ -9,6 +9,7 @@
       attribute: :email_subscriber,
       data: false,
       selectable_options: [true, false, nil],
+      include_blank_option: true,
     )
 
     render(

spec/features/form_spec.rb

@@ -77,4 +77,36 @@
       expect(element_selections.first("option").value).not_to eq("")
     end
   end
+
+  context "include_blank option for select" do
+    it "should have blank option if set to true" do
+      dashboard = CustomerDashboard.new
+      fields = dashboard.attribute_types
+      kind = fields[:kind]
+      kind.options[:include_blank] = true
+
+      expect(kind.deferred_class).to eq(Administrate::Field::Select)
+      expect(kind.options[:include_blank]).to eq(true)
+
+      visit new_admin_customer_path
+      element_selections = find("select[name=\"customer[kind]\"]")
+
+      expect(element_selections.first("option").value).to eq("")
+    end
+
+    it "should not have blank option if set to false" do
+      dashboard = CustomerDashboard.new
+      fields = dashboard.attribute_types
+      kind = fields[:kind]
+      kind.options[:include_blank] = false
+
+      expect(kind.deferred_class).to eq(Administrate::Field::Select)
+      expect(kind.options[:include_blank]).to eq(false)
+
+      visit new_admin_customer_path
+      element_selections = find("select[name=\"customer[kind]\"]")
+
+      expect(element_selections.first("option").value).not_to eq("")
+    end
+  end
 end