let custom values return typed values

this allows to have type-correct JSON output, e.g.:

12 instead of "12"
true instead of "1"

app/models/custom_value.rb

@@ -38,6 +38,32 @@ class CustomValue < ActiveRecord::Base
 
   after_initialize :set_default_value
 
+  # returns the value of this custom value, but converts it according to the field_format
+  # of the custom field beforehand
+  def typed_value
+    return nil if value.nil?
+
+    # strings may be blank, all other types can only be nil if their value is blank
+    return nil if value.blank? && !(['string', 'text'].include?(custom_field.field_format))
+
+    case custom_field.field_format
+    when 'int'
+      value.to_i
+    when 'float'
+      value.to_f
+    when 'date'
+      Date.iso8601(value)
+    when 'bool'
+      value == '1'
+    when 'user'
+      User.find(value)
+    when 'version'
+      Version.find(value)
+    else
+      value
+    end
+  end
+
   def set_default_value
     if new_record? && custom_field && (customized_type.blank? || (customized && customized.new_record?))
       self.value ||= custom_field.default_value

lib/api/v3/utilities/custom_field_injector.rb

@@ -183,9 +183,10 @@ module API
         def link_value_getter_for(custom_field, path_method)
           -> (*) {
             custom_value = represented.custom_value_for(custom_field)
-            value = custom_value.value if custom_value
+            value = custom_value.typed_value if custom_value
+            path = api_v3_paths.send(path_method, value.is_a?(String) ? value : value.id) if value
 
-            { href: (api_v3_paths.send(path_method, value) if value) }
+            { href: path }
           }
         end
 
@@ -214,7 +215,7 @@ module API
         def property_value_getter_for(custom_field)
           -> (*) {
             custom_value = custom_value_for(custom_field)
-            value = custom_value.value if custom_value
+            value = custom_value.typed_value if custom_value
 
             if custom_field.field_format == 'text'
               ::API::Decorators::Formattable.new(value, format: 'plain')

spec/lib/api/v3/utilities/custom_field_injector_spec.rb

@@ -181,7 +181,7 @@ describe ::API::V3::Utilities::CustomFieldInjector do
     let(:represented) {
       double('represented',
              custom_value_for: double('custom_value',
-                                      value: custom_value))
+                                      typed_value: custom_value))
     }
     let(:custom_value) { '' }
     let(:modified_class) { Class.new(::API::Decorators::Single) }
@@ -192,7 +192,7 @@ describe ::API::V3::Utilities::CustomFieldInjector do
     end
 
     context 'link custom field' do
-      let(:custom_value) { '2' }
+      let(:custom_value) { FactoryGirl.build(:user, id: 2) }
       let(:field_format) { 'user' }
 
       it_behaves_like 'has an untitled link' do
@@ -221,7 +221,7 @@ describe ::API::V3::Utilities::CustomFieldInjector do
     context 'int custom field' do
       it_behaves_like 'injects property custom field' do
         let(:field_format) { 'int' }
-        let(:custom_value) { '42' }
+        let(:custom_value) { 42 }
         let(:json_value) { 42 }
         let(:expected_setter) { json_value }
       end
@@ -230,7 +230,7 @@ describe ::API::V3::Utilities::CustomFieldInjector do
     context 'float custom field' do
       it_behaves_like 'injects property custom field' do
         let(:field_format) { 'float' }
-        let(:custom_value) { '3.14' }
+        let(:custom_value) { 3.14 }
         let(:json_value) { 3.14 }
         let(:expected_setter) { json_value }
       end
@@ -239,7 +239,7 @@ describe ::API::V3::Utilities::CustomFieldInjector do
     context 'bool custom field' do
       it_behaves_like 'injects property custom field' do
         let(:field_format) { 'bool' }
-        let(:custom_value) { '1' }
+        let(:custom_value) { true }
         let(:json_value) { true }
         let(:expected_setter) { json_value }
       end
@@ -248,7 +248,7 @@ describe ::API::V3::Utilities::CustomFieldInjector do
     context 'date custom field' do
       it_behaves_like 'injects property custom field' do
         let(:field_format) { 'date' }
-        let(:custom_value) { Date.today.to_date.iso8601 }
+        let(:custom_value) { Date.today.to_date }
         let(:json_value) { custom_value.to_date.iso8601 }
         let(:expected_setter) { json_value }
       end