多态has_and_belongs_to_many关联

如何解决多态has_and_belongs_to_many关联

我有一个具有以下结构的联接表：

  create_table "enrollment_auth",id: false,force: :cascade do |t|
    t.integer "enrollment_id"
    t.string "authorizable_type"
    t.bigint "authorizable_id"
  end

这里的想法是我想将架构中的各种记录与注册相关联（像用户一样考虑）。这是我的示例数据：

+---------------+--------------------+------------------+
| ENROLLMENT_ID |  AUTHORIZABLE_TYPE |  AUTHORIZABLE_ID |
+---------------+--------------------+------------------+
|               |                    |                  |
| 1             |  Location          |  1               |
|               |                    |                  |
| 1             |  Location          |  2               |
|               |                    |                  |
| 1             |  Asset             |  8               |
+---------------+--------------------+------------------+

我要寻找的是我的has_and_belongs_to_many :auth_locations模型中的has_many或Enrollment关系，以获取所有特定的多态集。即。 Enrollment.last.auth_locations或Enrollment.last.auth_assets等

我有这个，看起来很亲密：

  has_and_belongs_to_many :auth_locations,-> { where "enrollment_auth.authorizable_type = 'Location'" },join_table: :enrollment_auth,class_name: 'Location',association_foreign_key: 'authorizable_id'

并在控制台上

[42] pry(main)> Enrollment.last.auth_location_ids
  Enrollment Load (0.4ms)  SELECT  "enrollments".* FROM "enrollments" ORDER BY "enrollments"."id" DESC LIMIT $1  [["LIMIT",1]]
   (0.4ms)  SELECT "locations"."id" FROM "locations" INNER JOIN "enrollment_auth" ON "locations"."id" = "enrollment_auth"."authorizable_id" WHERE "locations"."company_id" = 9 AND "enrollment_auth"."enrollment_id" = $1 AND (enrollment_auth.authorizable_type = 'Location')  [["enrollment_id",99]]
=> []

这是一个空集，因为我还没有任何连接表条目，这是下一个问题。为文档（https://guides.rubyonrails.org/association_basics.html#has-and-belongs-to-many-association-reference付费），我现在应该可以这样做：

[43] pry(main)> Enrollment.last.auth_locations.build(authorizable_id: 12)
  Enrollment Load (0.3ms)  SELECT  "enrollments".* FROM "enrollments" ORDER BY "enrollments"."id" DESC LIMIT $1  [["LIMIT",1]]
NoMethodError: undefined method `build' for nil:NilClass
from (pry):43:in `__pry__'
[44] pry(main)>

直接建立新的关联，但是失败。我觉得我在这里错过了一个小细节。