小编And*_*ius的帖子

需要解决的错误:

ActiveRecord :: StatementInvalid:Mysql2 :: Error:无法删除或更新父行:外键约束失败(slap_chat_development.chatrooms,CONSTRAINT fk_rails_496733c195 FOREIGN KEY(group_id)REFERENCES groups(id)):DELETE FROM groupsWHERE groups.id= 1

问题是:

• 有人可以指导我从哪里修复此错误.

正如我所看到的问题在表groups和chatrooms表之间的关系中持续存在.

更多详情:

schema.rb

ActiveRecord::Schema.define(version: 20160606100750) do

  create_table "chatrooms", force: :cascade do |t|
    t.integer  "group_id",   limit: 4
    t.string   "name",       limit: 255
    t.datetime "created_at",             null: false
    t.datetime "updated_at",             null: false
  end

  add_index "chatrooms", ["group_id"], name: "index_chatrooms_on_group_id", using: :btree

  create_table "chatrooms_users", force: :cascade do |t|
    t.integer  "chatroom_id", limit: 4
    t.integer …

如何在同一方法中产生两个不同的块

示例代码:

def by_two(n,a)
    yield n
    yield a
end

proc1 = proc {|x| p x * 2}
proc2 = proc {|x| x + 100}

by_two(10, 300, &proc1, &proc2)

错误是这样的 -

main.rb:7: syntax error, unexpected ',', expecting ')'
by_two(10, 300, &proc1, &proc2)

有什么建议在哪里,哪些是错的？谢谢