Question

我对Rails（4，Ruby 2.0）相对较新，目前有一个与我合作的has_many + belongs_to协会。我试图建模的协会是一个“白天”。有几个＆＃39; Timeslots＆＃39;每个时段都属于一天。

我的模特看起来像这样：

Day.rb

class Day < ActiveRecord::Base
  has_many :timeslots
  belongs_to :calendar
end

Timeslot.rb

class Timeslot < ActiveRecord::Base
  has_many :events
  belongs_to :day
  validates_presence_of :start_time
  validates_presence_of :end_time
  validates_presence_of :day_id
end

Day和Timeslot的架构：

  create_table "days", force: true do |t| 
    t.datetime "created_at"
    t.datetime "updated_at"
  end 

  create_table "timeslots", force: true do |t| 
    t.datetime "created_at"
    t.datetime "updated_at"
    t.time     "start_time"
    t.time     "end_time"
    t.integer  "day_id"
  end

我看到的问题是我无法将Timeslot对象正确保存到数据库中：

在控制台中：

d = Day.new
=> #<Day id: nil, created_at: nil, updated_at: nil, date: nil> 
d.id = 20140322
=> 20140322 
d.save
(0.1ms)  begin transaction
SQL (22.2ms)  INSERT INTO "days" ("created_at", "date", "id", "updated_at") VALUES (?, ?,     ?, ?)  [["created_at", Sat, 22 Mar 2014 21:28:27 PDT -07:00], ["id", 20140322], ["updated_at", Sat, 22 Mar 2014 21:28:27 PDT -07:00]]
 (6.8ms)  commit transaction
 => true

 Day.all
 Day Load (0.3ms)  SELECT "days".* FROM "days"
 => #<ActiveRecord::Relation [#<Day id: 20140322, created_at: nil, updated_at: nil>]> 
 t = Timeslot.new
 => #<Timeslot id: nil, created_at: nil, updated_at: nil, start_time: nil, end_time: nil, day_id: nil> 
 t.start_time = Time.now
 2014-03-22 21:28:52 -0700 
 t.end_time = Time.now
 2014-03-22 21:28:57 -0700 
 t.day_id = 20140322
 => 20140322 
 t.save
(0.1ms)  begin transaction
SQL (0.8ms)  INSERT INTO "timeslots" ("created_at", "day_id", "end_time", "start_time",  "updated_at") VALUES (?, ?, ?, ?, ?)  [["created_at", Sat, 22 Mar 2014 21:29:06 PDT -07:00], ["day_id", 20140322], ["end_time", 2014-03-22 21:28:57 -0700], ["start_time", 2014-03-22 21:28:52 -0700], ["updated_at", Sat, 22 Mar 2014 21:29:06 PDT -07:00]]
(7.6ms)  commit transaction
=> true



# Here's the problem
Day.all
Day Load (0.2ms)  SELECT "days".* FROM "days"
=> #<ActiveRecord::Relation [#<Day id: 20140322, created_at: nil, updated_at: nil>]> 
2.0.0-p247 :015 > Timeslot.all
Timeslot Load (0.2ms)  SELECT "timeslots".* FROM "timeslots"
=> #<ActiveRecord::Relation [#<Timeslot id: 2, created_at: nil, updated_at: nil, start_time: nil, end_time: nil, day_id: 20140322>]> 
a = Day.all.first
Day Load (0.2ms)  SELECT "days".* FROM "days" ORDER BY "days"."id" ASC LIMIT 1
=> #<Day id: 20140322, created_at: nil, updated_at: nil> 
a.timeslots
Timeslot Load (0.3ms)  SELECT "timeslots".* FROM "timeslots" WHERE "timeslots"."day_id" = ?  [["day_id", 20140322]]

=＆GT; ＃]＆GT;

事实上，Timeslot对象似乎没有被正确创建。我不确定为什么会这样。

Answer 1

我的文件中有几件我不理解的东西，我认为您应该使用ruby命令行工具来生成文件，以确保不会出错。例如，您的created_At和updated_at不正常，应该自动填充，而不是。

我建议您删除文件并启动这些命令

rails g model day calendar:references
rails g model timeslot start_time:time end_time:time  day:references

然后将关联添加到模型

class Day < ActiveRecord::Base
  has_many :timeslots
  belongs_to :calendar
end
class Timeslot < ActiveRecord::Base
  has_many :events
  belongs_to :day
  validates_presence_of :start_time
  validates_presence_of :end_time
  # validates_presence_of :day_id #Remove this line for now
end

您可以启动rake db:migrate并重试（顺便说一下Day.all.first与Day.first相同而不是t.day_id = ...，请尝试t.day = Day.first

Rails对象的属性不保存

1 个答案: