我有几个表，它们都有关联的外键约束，每个表都以分层方式引用另一个表，如下所述。
当我试图摧毁一个公司，至少有1个项目，至少有1个任务，至少有1个任务时间像这样...

irb(main):014:0> Company.first.destroy

我得到了下面的输出和错误。我现在的印象是，仅仅使用dependent: :delete_all并不能处理外键约束，这是真的吗？如果是这样，我该如何处理这种情况？我知道before_destroy回调，在这种情况下我必须使用它吗？如果是这样，如何临时禁用外键约束以销毁该行中所有关联的行？什么？更让人困惑的是，我有一个旧的Rails项目，它有相同的表/模型设置，只是它是一个带有外键约束的单一model_a has_many model_bs, dependent: delete_all关系，我可以ModelB.destroy_all，它工作正常。所以我不明白，我也读过一些帖子，在表上设置级联删除是有效的，还有一些帖子说如果你自己用代码处理它，就不需要这样做;如果解决方案不太复杂的话，我想在我的代码中处理这个问题。

Company Load (0.4ms)  SELECT  "companies".* FROM "companies" ORDER BY 
                              "companies"."id" ASC LIMIT $1 [["LIMIT", 1]]
   (0.2ms)  BEGIN
             SQL (0.9ms)  DELETE FROM "projects" 
                          WHERE "projects"."company_id" = $1 [["company_id", 3]]
   (0.1ms)  ROLLBACK
             Traceback (most recent call last):
   1: from (irb):13
             ActiveRecord::InvalidForeignKey (PG::ForeignKeyViolation: ERROR:  update or delete on table "projects" violates foreign key constraint "fk_rails_02e851e3b7" on table "tasks"
                          DETAIL:  Key (id)=(4) is still referenced from table "tasks".
                        : DELETE FROM "projects" WHERE "projects"."company_id" = $1)

架构

# /db/schema.rb

create_table "companies", force: :cascade do |t|
...
end

create_table "projects", force: :cascade do |t|
...
end

create_table "tasks", force: :cascade do |t|
...
end

create_table "task_times", force: :cascade do |t|
...
end
...

add_foreign_key "projects", "companies"
add_foreign_key "tasks", "projects"
add_foreign_key "task_times", "tasks"

型

型号

# /models/company.rb

class Company < ApplicationRecord
  has_many :projects, dependent: :delete_all
...
end

# /models/project.rb

class Project < ApplicationRecord
  has_many :tasks, dependent: :delete_all
...
end

# /models/task.rb

class Task < ApplicationRecord
  has_many :task_times, dependent: :delete_all
...
end

# /models/task_time.rb

class TaskTime < ApplicationRecord
...
end