我正在使用Rails 4和Mongoid。我有以下型号：
class Country
include Mongoid::Document
field :iso
field :name
embedded_in :user
end
class User
include Mongoid::Document
field :email
field :name
embeds_one :country
end
在编辑用户视图时，我想将下拉列表放在国家/地区，以便选择所选国家/地区作为嵌入用户记录。我试着用这样的东西：
<%= f.select :country, Country.all.collect { |c| [c.name, c._id] }, :prompt => 'Please select' %>
但它看起来不起作用：
undefined method `__metadata' for "5324c9f7416c65a032070000":String
任何建议都会有所帮助。感谢。
Started POST "/users" for 127.0.0.1 at 2014-03-16 16:31:32 +0200
Processing by Devise::RegistrationsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"UzETkbI3MNGBJQg7IhzI6jD5dQCZrvjU0JAgkReTSak=", "user"=>{"first_name"=>"", "last_name"=>"", "email"=>"", "birth_date"=>"", "gender"=>"", "marital_status"=>"", "city"=>"", "country"=>"5324c9f5416c65a032000000", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]"}, "commit"=>"Sign up"}
Completed 500 Internal Server Error in 4ms
NoMethodError - undefined method `__metadata' for "5324c9f5416c65a032000000":String:
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/proxy.rb:141:in `characterize_one'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/embedded/one.rb:20:in `block in initialize'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/proxy.rb:42:in `init'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/embedded/one.rb:19:in `initialize'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/accessors.rb:44:in `new'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/accessors.rb:44:in `create_relation'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/accessors.rb:26:in `__build__'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/accessors.rb:233:in `block (2 levels) in setter'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/accessors.rb:140:in `without_autobuild'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/relations/accessors.rb:229:in `block in setter'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/attributes/processing.rb:141:in `block in process_relations'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/attributes/processing.rb:136:in `each_pair'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/attributes/processing.rb:136:in `process_relations'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/attributes/processing.rb:122:in `process_pending'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/attributes/processing.rb:29:in `process_attributes'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/document.rb:110:in `block in initialize'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/threaded/lifecycle.rb:84:in `_building'
() Users/alex/.rvm/gems/ruby-2.1.0/bundler/gems/mongoid-164755a9d038/lib/mongoid/document.rb:104:in `initialize'
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rack (1.5.2) lib/rack/runtime.rb:17:in `call'
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rack (1.5.2) lib/rack/lock.rb:17:in `call'
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rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
/Users/alex/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
/Users/alex/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
/Users/alex/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'
答案 0 :(得分：0)
问题是您没有在用户中正确设置国家/地区...
尝试将以下内容添加到用户模型中 如果你想以正常的mongoid方式设置国家或用id ..
def country
@country ||= Country.where(id: country_id).first
end
def country=(obj)
case obj.class
when String
self.country_id = obj
@country = Country.find(obj)
when Country
self.country_id = obj.id
@country = obj
end
end