模式

Question

我是Rails的新手，我对ORM关系有疑问。

当我访问/ admin / health_concerns_lists

时

显示。

Showing /Users/sbpipb/.rvm/gems/ruby-2.1.1/bundler/gems/activeadmin-a2cd9604c2d9/app/views/active_admin/resource/index.html.arb where line #2 raised:

undefined method `klass' for nil:NilClass
Extracted source (around line #2):
1

  insert_tag renderer_for(:index)

这是我的关系。

class HealthProfile < ActiveRecord::Base
    #table - health_profiles
    has_many :health_concerns, dependent: :destroy
    has_many :health_concerns_lists, :through => :health_concerns ,dependent: :destroy
end

class HealthConcern < ActiveRecord::Base
    #table - health_concerns
    belongs_to :health_profile
    belongs_to :health_concerns_list
end

class HealthConcernsList < ActiveRecord::Base
    self.table_name = "health_concerns_list"
    has_many :health_concerns, dependent: :destroy
    has_many :health_profiles, :through => :health_concerns_lists, dependent: :destroy
end

模式

health_profile
id
name

health_concerns
id
health_profile_id
health_concerns_id

health_concerns_list
id
name

我知道，我的命名惯例听起来不对。

Answer 1

class HealthProfile < ActiveRecord::Base
    #table - health_profiles
    has_many :health_concerns, dependent: :destroy
    has_many :health_concerns_lists, :through => :health_concerns ,dependent: :destroy
end

我想你需要纠正这个部分：

class HealthConcern < ActiveRecord::Base
    #table - health_concerns
    belongs_to :health_profile
    has_many :health_concerns_list
end

class HealthConcernsList < ActiveRecord::Base
    belongs_to :health_concerns, dependent: :destroy
    belongs_to :health_profiles, dependent: :destroy
end

Answer 2

尝试更改

class HealthProfile < ActiveRecord::Base
    # ...
    has_many :health_concerns_lists, :through => :health_concerns, dependent: :destroy
end

成：

class HealthProfile < ActiveRecord::Base
    # ...
    has_many :health_concerns_lists, :through => :health_concerns, dependent: :destroy
    has_many :health_concerns
end

对于has_many through: ...

的每个型号

Answer 3

尝试删除：

self.table_name = "health_concerns_list"

通过Rails约定，您无需为模型指定表名。他们的模型名称（HealthConcernsList）将为tableize'到health_conerns_lists。

如果您必须使用单个table_name，请尝试：

class HealthConcernsList < ActiveRecord::Base
  self.pluralize_table_names = false
end

http://guides.rubyonrails.org/3_1_release_notes.html#active-record

未定义的方法`klass＆＃39;为零：NilClass

模式

3 个答案: