无法查询 Rails 中的 hstore 属性

Question

我已经为我的模型添加了一个 hstore 属性：

class ChangePerDayAverageInterestToHstore < ActiveRecord::Migration
  def change
      add_column :companies, :per_day_average_interest, :hstore
  end
end

现在，当我通过控制台生成项目时，我可以毫无问题地查询它。像这样：

irb(main):002:0> t = Company.new per_day_average_interest: {1 => 10, 2 => 3}
irb(main):011:0> t.per_day_average_interest 
=> {"1"=>"10", "2"=>"3"}
irb(main):013:0> t.per_day_average_interest["1"]                                                                                  => "10"
irb(main):014:0> t.per_day_average_interest["2"]
=> "3"

当我保存它，然后查询它时，我得到一个 No Method 错误：

irb(main):028:0> t.save!
(0.2ms)  BEGIN                                                                                                                  SQL (0.3ms)  INSERT INTO "companies" ("created_at", "per_day_average_interest", "updated_at") VALUES (, , ) RETURNING "id"  [["created_at", "2015-06-08 19:24:39.694533"], ["per_day_average_interest", "\"1\"=>\"10\",\"2\"=>\"3\""], ["updated_at", "2015-06-08 19:24:39.694533"]]
(21.4ms)  COMMIT                                                                                                                
=> true 
irb(main):029:0> d = Company.where(:id => 44)
  Company Load (0.5ms)  SELECT "companies".* FROM "companies"  WHERE "companies"."id" = 44
=> #<ActiveRecord::Relation [#<Company id: 44, name: nil, average: nil, created_at: "2015-06-08 19:24:39", updated_at: "2015-06-08 19:24:39", revenue_average: nil, country: nil, job: nil, model_name:
 nil, average_daily_interest: nil, per_day_average_interest: {"1"=>"10", "2"=>"3"}>]>
irb(main):030:0> d.per_day_average_interest
NoMethodError: undefined method `per_day_average_interest' for #<Company::ActiveRecord_Relation:0x007fa16d296dd0>
from /home/action/.gem/ruby/2.1.1/gems/activerecord-4.1.0/lib/active_record/relation/delegation.rb:136:in `method_missing'      
from /home/action/.gem/ruby/2.1.1/gems/activerecord-4.1.0/lib/active_record/relation/delegation.rb:99:in `method_missing'       
from (irb):30
from /home/action/.gem/ruby/2.1.1/gems/railties-4.1.0/lib/rails/commands/console.rb:90:in `start'                                                                                              
        from /home/action/.gem/ruby/2.1.1/gems/railties-4.1.0/lib/rails/commands/console.rb:9:in `start'                                                                                               
        from /home/action/.gem/ruby/2.1.1/gems/railties-4.1.0/lib/rails/commands/commands_tasks.rb:69:in `console'                                                                                     
        from /home/action/.gem/ruby/2.1.1/gems/railties-4.1.0/lib/rails/commands/commands_tasks.rb:40:in `run_command!'                                                                                
        from /home/action/.gem/ruby/2.1.1/gems/railties-4.1.0/lib/rails/commands.rb:17:in `<top (required)>'                                                                                           
        from bin/rails:4:in `require'                                                                                                                                                                  
        from bin/rails:4:in `<main>'

我是不是查询错了？有什么我想念的吗？

谢谢！

Answer 1

如你所见d是ActiveRecord::Relation对象，它是过滤后所有Company对象的包装器where。 reader 方法 per_day_average_interest 是在 Company 模型实例上定义的，因此您需要调用，如下所示。

d.first.per_day_average_interest

如果您想要所有值 d.pluck(:per_day_average_interest)。

Answer 2

where声明returns对象的集合和你的列属于一个对象所以你需要做以下 d = Company.where(:id => 44).first

无法查询 Rails 中的 hstore 属性

Unable to query hstore attribute in Rails

postgresql

ruby-on-rails

hstore