feat(graphql): add postalCode to champ commune

app/graphql/schema.graphql

@@ -404,7 +404,16 @@ type Commune {
   Le code INSEE
   """
   code: String!
+
+  """
+  Le nom de la commune
+  """
   name: String!
+
+  """
+  Le code postal
+  """
+  postalCode: String
 }
 
 type CommuneChamp implements Champ {

app/graphql/types/champs/commune_champ_type.rb

@@ -3,29 +3,20 @@ module Types::Champs
     implements Types::ChampType
 
     class CommuneType < Types::BaseObject
-      field :name, String, null: false
+      field :name, String, "Le nom de la commune", null: false
       field :code, String, "Le code INSEE", null: false
+      field :postal_code, String, "Le code postal", null: true, method: :code_postal
     end
 
     field :commune, CommuneType, null: true
     field :departement, Types::Champs::DepartementChampType::DepartementType, null: true
 
     def commune
-      if object.code?
+      object if object.code?
-        {
-          name: object.to_s,
-          code: object.code
-        }
-      end
     end
 
     def departement
-      if object.departement?
+      object.departement if object.departement?
-        {
-          name: object.name_departement,
-          code: object.code_departement
-        }
-      end
     end
   end
 end