【发布时间】：2015-02-17 14:52:59
【问题描述】：
我在尝试匹配我正在开发的应用程序中的用户和食谱的饮食要求之间的多态关联时遇到问题。在控制台中，我可以让它工作——如果我将一个用户的饮食要求 id 等于“[2]”与一个具有相同孩子的食谱相匹配，它就可以工作。
但是，当我运行应用程序时，尽管调用了相同的用户和配方，但比较两者的方法评估为“假”。
希望这很清楚，这里有一个小代码来解释这一点：
在控制台中
one = User.first
two = Recipe.first
one.dietary_requirement_ids.any? && ((one.dietary_requirement_ids & two.dietary_requirement_ids) == one.dietary_requirement_ids)
# returns true, as it should
但是，在视图中...
我使用视图可访问的辅助方法，如下：
def dietary_requirement_matcher(one, two)
one.dietary_requirement_ids.any? && ((one.dietary_requirement_ids & two.dietary_requirement_ids) == one.dietary_requirement_ids)
end
这样：
<% Recipe.all.each do |recipe| %>
<li><%= dietary_requirement_matcher(@user, recipe) %></li>
<% end %>
<!-- which all return false, including those that shouldn't! -->
我不知道为什么它会在控制台中返回正确的结果而不是视图。我已经尝试了一些方法来调试它，如下所示：
将帮助方法更改为以下内容可以正确评估食谱（即为用户替换正确的dietary_requirement_ids）：
def dietary_requirement_matcher(one, two)
([1, 2] & two.dietary_requirement_ids) == [1, 2]
end
@user.inspect 提取正确的用户。但是，@user.dietary_requirement_ids.inspect 拉出一个空数组（尽管仍在控制台中工作）。
我检查了用户和食谱都正确保存在控制台中。
这里有一些额外的代码可能有助于解决这个问题：
模型
食谱
has_many :dietary_requirements, as: :classifiable
用户
has_many :dietary_requirements, as: :classifiable
饮食要求
belongs_to :classifiable, polymorphic: true
控制器
@recipes = Recipe.all
@user = current_user #auth method - debug shows this picking up the correct user in the view, albeit not their dietary requirements
查看（不完整，用于在我修复此问题时进行调试）
<ul>
<% Recipe.all.each do |recipe| %>
<li><%= recipe.name %> = <%= dietary_requirement_matcher(@user, recipe) %></li>
<% end %>
</ul>
<p><%= dietary_requirement_matcher(@user, Recipe.first) %></p> <!-- returns false, when I'm after true -->
<p><%= @user.dietary_requirements.inspect %></p> <!-- returns '#<ActiveRecord::Associations::CollectionProxy []>' -->
我认为解决此问题的方法可能真的很简单，我只是没有发现这一点，因为我是一个无知的新手。如果有人可以提供帮助，我将非常感激！史蒂夫。
编辑
进行更多挖掘后，我感觉这可能是应用在数据库中查找信息的方式存在问题。我正在为用户（通过冰箱）和配方成分（有效！）运行类似的逻辑，并且日志显示了访问这两条信息的不同路径。
我认为，因为多态关系在搜索数据库时会寻找一个classifiable_id 和（至关重要的）一个classifiable_type，所以这个classifiable 类型在这里混淆了。我感觉 SQLite 正在寻找用户的饮食要求，但 classifiable_type 是“Recipe”而不是“User”。
任何人都可以在这里阐明我的想法吗？那里有什么感觉或疯子的胡言乱语？这是页面加载时的日志：
Started GET "/fridges/meals" for 151.229.93.203 at 2015-02-17 16:26:42 +0000
Processing by FridgesController#meals as HTML
#code for matching User Ingredients to Recipe Ingredients
User Load (0.7ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]]
(0.3ms) SELECT COUNT(*) FROM "recipes"
Recipe Load (0.3ms) SELECT "recipes".* FROM "recipes"
Ingredient Exists (0.2ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 1]]
Fridge Load (0.2ms) SELECT "fridges".* FROM "fridges" WHERE "fridges"."user_id" = ? LIMIT 1 [["user_id", 2]]
(0.2ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "fridge_ingredients" ON "ingredients"."id" = "fridge_ingredients"."ingredient_id" WHERE "fridge_ingredients"."fridge_id" = ? [["fridge_id", 5]]
(0.2ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 1]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 1]]
(0.2ms) SELECT "dietary_requirements".id FROM "dietary_requirements" WHERE "dietary_requirements"."classifiable_id" = ? AND "dietary_requirements"."classifiable_type" = ? [["classifiable_id", 2], ["classifiable_type", "User"]]
Ingredient Load (0.2ms) SELECT "ingredients".* FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 1]]
Ingredient Exists (0.1ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 2]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "fridge_ingredients" ON "ingredients"."id" = "fridge_ingredients"."ingredient_id" WHERE "fridge_ingredients"."fridge_id" = ? [["fridge_id", 5]]
(0.1ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 2]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 2]]
Ingredient Exists (0.1ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 3]]
Ingredient Exists (0.1ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 4]]
Rendered shared/_matcher.html.erb (21.3ms)
CACHE (0.0ms) SELECT "recipes".* FROM "recipes"
CACHE (0.0ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 1]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "fridge_ingredients" ON "ingredients"."id" = "fridge_ingredients"."ingredient_id" WHERE "fridge_ingredients"."fridge_id" = ? [["fridge_id", 5]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 1]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 1]]
CACHE (0.0ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 2]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "fridge_ingredients" ON "ingredients"."id" = "fridge_ingredients"."ingredient_id" WHERE "fridge_ingredients"."fridge_id" = ? [["fridge_id", 5]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 2]]
CACHE (0.0ms) SELECT "ingredients".id FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? [["recipe_id", 2]]
CACHE (0.0ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 3]]
CACHE (0.0ms) SELECT 1 AS one FROM "ingredients" INNER JOIN "recipe_ingredients" ON "ingredients"."id" = "recipe_ingredients"."ingredient_id" WHERE "recipe_ingredients"."recipe_id" = ? LIMIT 1 [["recipe_id", 4]]
#code for matching the User and Recipe Dietary Requirements
CACHE (0.0ms) SELECT "recipes".* FROM "recipes"
CACHE (0.0ms) SELECT "dietary_requirements".id FROM "dietary_requirements" WHERE "dietary_requirements"."classifiable_id" = ? AND "dietary_requirements"."classifiable_type" = ? [["classifiable_id", 2], ["classifiable_type", "User"]]
CACHE (0.0ms) SELECT "dietary_requirements".id FROM "dietary_requirements" WHERE "dietary_requirements"."classifiable_id" = ? AND "dietary_requirements"."classifiable_type" = ? [["classifiable_id", 2], ["classifiable_type", "User"]]
CACHE (0.0ms) SELECT "dietary_requirements".id FROM "dietary_requirements" WHERE "dietary_requirements"."classifiable_id" = ? AND "dietary_requirements"."classifiable_type" = ? [["classifiable_id", 2], ["classifiable_type", "User"]]
CACHE (0.0ms) SELECT "dietary_requirements".id FROM "dietary_requirements" WHERE "dietary_requirements"."classifiable_id" = ? AND "dietary_requirements"."classifiable_type" = ? [["classifiable_id", 2], ["classifiable_type", "User"]]
Recipe Load (0.4ms) SELECT "recipes".* FROM "recipes" ORDER BY "recipes"."id" ASC LIMIT 1
CACHE (0.0ms) SELECT "dietary_requirements".id FROM "dietary_requirements" WHERE "dietary_requirements"."classifiable_id" = ? AND "dietary_requirements"."classifiable_type" = ? [["classifiable_id", 2], ["classifiable_type", "User"]]
DietaryRequirement Load (0.2ms) SELECT "dietary_requirements".* FROM "dietary_requirements" WHERE "dietary_requirements"."classifiable_id" = ? AND "dietary_requirements"."classifiable_type" = ? [["classifiable_id", 2], ["classifiable_type", "User"]]
Rendered fridges/meals.html.erb within layouts/application (42.3ms)
Cuisine Load (0.3ms) SELECT "cuisines".* FROM "cuisines"
Category Load (0.2ms) SELECT "categories".* FROM "categories"
Rendered shared/_header.html.erb (3.3ms)
Completed 200 OK in 593ms (Views: 579.3ms | ActiveRecord: 4.2ms)
【问题讨论】：
标签： ruby-on-rails methods parent-child polymorphic-associations rails-console