Rails STI和has_many通过关联不起作用,SQLException:没有这样的表
我有以下型号:
class Test < ApplicationRecord end class Exam < Test end class Practice < Test has_many :relations has_many :questions, through: :relations end class Relation < ApplicationRecord belongs_to :practice belongs_to :question end class Question < ApplicationRecord has_many :relations has_many :practices, through: :relations end
这是我的架构:
create_table "questions", force: :cascade do |t| t.string "title" t.text "text" t.datetime "created_at", null: false t.datetime "updated_at", null: false end create_table "relations", force: :cascade do |t| t.integer "practice_id" t.integer "question_id" t.datetime "created_at", null: false t.datetime "updated_at", null: false t.index ["practice_id"], name: "index_relations_on_practice_id" t.index ["question_id"], name: "index_relations_on_question_id" end create_table "tests", force: :cascade do |t| t.string "name" t.datetime "created_at", null: false t.datetime "updated_at", null: false end
当我在rails控制台中尝试时:
@p = Practice.new @p.save @q = Question.new @q.save Practice.last.questions << Question.last
我收到此错误:
Question Load (0.2ms) SELECT "questions".* FROM "questions" ORDER BY "questions"."id" DESC LIMIT ? [["LIMIT", 1]] (0.1ms) begin transaction SQL (0.4ms) INSERT INTO "relations" ("practice_id", "question_id", "created_at", "updated_at") VALUES (?, ?, ?, ?) [["practice_id", 2], ["question_id", 1], ["created_at", "2017-10-26 06:09:42.581082"], ["updated_at", "2017-10-26 06:09:42.581082"]] (0.1ms) rollback transaction ActiveRecord::StatementInvalid: SQLite3::SQLException: no such table: main.practices: INSERT INTO "relations" ("practice_id", "question_id", "created_at", "updated_at") VALUES (?, ?, ?, ?)
错误显而易见,它没有找到表格practices
但我该如何解决这个问题呢? 我不明白如何指定使用表测试,而不是实践。 任何帮助表示赞赏
应该没有practices
表,因为Practice
inheritance了Test
并且你想使用STI模式。 我在我的机器上重复了你的模型和架构,它按预期工作。 所以要么你有一些SQLite
问题,要么有像spring
。
使用spring stop
平静弹簧然后尝试使用rails db:reset
重新创建db并确保没有错误。
此外,我希望它只是示例代码,在现实生活中,你没有将sql关系命名为relations
=)