PG::ForeignKeyViolation: 将 rails 中的 has_and_belongs_to_many 关联更改为 has_many :through 关联后出现错误

Question

我最近将 has_and_belongs_to_many (HABTM) 关联切换为 has_many :through 关联，现在由于违反外键约束，我有很多失败的测试。这是一个示例测试失败消息：

DRb::DRbRemoteError: PG::ForeignKeyViolation: ERROR:  update or delete on table "choices" violates foreign key constraint "fk_rails_d6ffbc38aa" on table "selections"
        DETAIL:  Key (id)=(506907318) is still referenced from table "selections"

这是创建关联的表单。

这是我的模型与相关协会...

models/variant.rb

class Variant < ApplicationRecord    
  has_many :selections
  has_many :choices, through: :selections
end

models/choice.rb

class Choice < ApplicationRecord
  has_many :variants, through: :selections

  belongs_to :option
end

models/selection.rb

class Selection < ApplicationRecord
  belongs_to :choice
  belongs_to :variant
end

以及相关的架构：

create_table "variants", force: :cascade do |t|
  t.string "sku"
  t.datetime "created_at", precision: 6, null: false
  t.datetime "updated_at", precision: 6, null: false
  t.bigint "account_id"
  t.bigint "product_id"
  t.index ["account_id"], name: "index_variants_on_account_id"
  t.index ["product_id"], name: "index_variants_on_product_id"
end

create_table "choices", force: :cascade do |t|
  t.string "name"
  t.datetime "created_at", precision: 6, null: false
  t.datetime "updated_at", precision: 6, null: false
  t.bigint "option_id"
  t.bigint "account_id"
  t.index ["account_id"], name: "index_choices_on_account_id"
  t.index ["option_id"], name: "index_choices_on_option_id"
end

create_table "selections", force: :cascade do |t|
  t.bigint "choice_id"
  t.bigint "variant_id"
  t.datetime "created_at", precision: 6
  t.datetime "updated_at", precision: 6
  t.index ["choice_id"], name: "index_selections_on_choice_id"
  t.index ["variant_id"], name: "index_selections_on_variant_id"
end

在浏览器中一切正常。只是我的测试失败了，所有失败的测试都有同样的外键错误。

我不想开始为我的模型添加关联和外键只是为了让我的测试通过，因为预期的行为在浏览器中起作用。

我正在使用固定装置进行测试。这是问题吗？我的灯具是否有可能导致此错误的原因？仅供参考，我想继续使用灯具而不是将应用切换到工厂。

test/fixtures/variants.yml

small_t_shirt_in_red:
  id: 1
  account: fuzz
  product: t_shirt
  sku: FUZZ-T-001
  choices: small, red

medium_generic_gadget_in_blue:
  id: 2
  account: generic_gadgets
  product: gadget
  sku: GENERIC-001
  choices: medium, blue


test/fixtures/choices.yml

small:
  name: Small

medium:
  name: Medium

large:
  name: Large

red:
  name: Red

blue:
  name: Blue


test/fixtures/selections.yml

small_t_shirt_selection:
  choice_id: 1
  variant_id: 1

red_t_shirt_selection:
  choice_id: 4
  variant_id: 1

medium_generic_selection:
  choice_id: 2
  variant_id: 2

blue_generic_selection:
  choice_id: 5
  variant_id: 2

Answer 1

尝试删除并重新创建您的测试数据库：

RAILS_ENV=test rails db:drop db:create

也许测试数据库中有一个主/开发数据库没有的外键约束。

Answer 2

更新

我发现了问题，所以在这里发布解决方案以防其他人需要它。

以下是有效的固定装置：

test/fixtures/variants.yml

small_t_shirt_in_red:
  account: fuzz
  product: t_shirt
  sku: FUZZ-T-001
  choices: small, red

medium_generic_gadget_in_blue:
  account: generic_gadgets
  product: gadget
  sku: GENERIC-001
  choices: medium, blue


test/fixtures/choices.yml

small:
  name: Small

medium:
  name: Medium

large:
  name: Large

red:
  name: Red

blue:
  name: Blue


test/fixtures/selections.yml

red_t_shirt_selection:
  choice: red
  variant: small_t_shirt_in_red

medium_generic_selection:
  choice: medium
  variant: medium_generic_gadget_in_blue

然后，我需要将我的模型更新为：

models/variant.rb

class Variant < ApplicationRecord
  has_many :selections, dependent: :destroy
  has_many :choices, through: :selections
end


models/choice.rb

class Choice < ApplicationRecord
  has_many :selections, dependent: :destroy
  has_many :variants, through: :selections

  belongs_to :option
end


models/selection.rb

class Selection < ApplicationRecord
  belongs_to :choice
  belongs_to :variant
end

我在Variant 和Choice 型号上都缺少has_many :selections, dependent: :destroy。