mongoid查詢軌3

Question

品牌新的MongoDB/mongoid和上的Ruby/Rails還是蠻綠色

軌控制檯上：

t = Task.all(:conditions => {:title => "task2"}) 

=> #<Mongoid::Criteria 
selector: {:title=>"task2"}, 
options: {}, 
class: Task, 
embedded: false> 


>> t.first 
=> #<Task _id: 4d7e2cdb73ec3227dd000009, title: "task2", latitude: 23.987904829, longitude: -12.9423875, created_by: "4d792d6973ec3248e3000001"> 

回報什麼，我所期望的，但

t = Task.where(:created_by => "4d792d6973ec3248e3000001") 

=> #<Mongoid::Criteria 
selector: {:created_by=>BSON::ObjectId('4d792d6973ec3248e3000001')}, 
options: {}, 
class: Task, 
embedded: false> 

>> t.first 
=> nil 

相同結果如下：

t = Task.all(:conditions => {:created_by => "4d792d6973ec3248e3000001"}) 

這裏是模型：

class Task 
    include Mongoid::Document 
    field :title 
    field :latitude,     :type => Float 
    field :longitude,     :type => Float 
    field :created_by 
end 

我究竟做錯了什麼？

更新例如：

>> Task.new(:title => "task8", :created_by => "4d792d6973ec3248e3000001") 
=> #<Task _id: 4d81037973ec32cc22000003, latitude: nil, longitude: nil, title: "task8", created_by: "4d792d6973ec3248e3000001"> 

>> t = Task.all(:conditions => {:created_by => "4d792d6973ec3248e3000001"}) 
=> #<Mongoid::Criteria 
selector: {:created_by=>BSON::ObjectId('4d792d6973ec3248e3000001')}, 
options: {}, 
class: Task, 
embedded: false> 

>> t.first 
=> nil 

我需要特別限定CREATED_BY爲：類型=>字符串？

Answer 1

看起來像created_by是作爲字符串存儲在您的文檔中，但然後您查詢查找ObjectId。 ObjectId和字符串不一樣。

嘗試改變

>> Task.new(:title => "task8", :created_by => "4d792d6973ec3248e3000001") 

到

>> Task.new(:title => "task8", :created_by => BSON::ObjectId("4d792d6973ec3248e3000001")) 

Answer 2

你必須包括在本mongoid功能在docs解釋說：

class Person 
    include Mongoid::Document 
    include Mongoid::Timestamps 
end