没有将 nil 隐式转换为字符串。 dbview_cti答案

【问题标题】：No implicit conversion of nil into String. dbview_cti没有将 nil 隐式转换为字符串。 dbview_cti
【发布时间】：2016-02-23 17:56:56
【问题描述】：

我使用dbview_cti gem 来制作类表继承 (CTI)。我有两个类 Person（抽象类）和 Client（继承 Person）。

问题：

当我尝试 make rake db:migrate 时，控制台写出这个错误：

StandardError: An error has occurred, this and all later migrations canceled:

    no implicit conversion of nil into String ../postgresql/utils.rb:24:in `quote_ident'

模范人物

class Person < ActiveRecord::Base
  self.abstract_class = true
  cti_base_class
end

模型客户端

class Client < Person
  cti_derived_class
end

迁移创建人

class CreatePeople < ActiveRecord::Migration
  def self.up
    create_table :persons do |t|
      t.string :pesel, null: false
      t.string :first_name, null: false
      t.string :last_name, null: false
      t.string :email, null: false
      t.date :data_of_birth, null: false
      t.string :password_digest, null: false
      t.timestamps null: false
    end
  end

  def self.down
    drop_table :persons
  end
end

迁移创建客户端

class CreateClients < ActiveRecord::Migration
  def change
    create_table :clients do |t|
      t.references :person
      t.timestamps null: false
    end

    cti_create_view('Client')
  end
end

有关错误的更多详细信息：

>     == 20160223135814 CreateClients: migrating ====================================
>     -- create_table(:clients)
>        -> 0.0348s
>     -- cti_create_view("Client")
>     rake aborted!
>     StandardError: An error has occurred, this and all later migrations canceled:
>     
>     no implicit conversion of nil into String/home/lukas/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql/utils.rb:24:in
> `quote_ident'
>     /home/lukas/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql/utils.rb:24:in
> `quoted'
>     /home/lukas/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql/quoting.rb:31:in
> `quote_table_name'
>     /home/lukas/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:738:in `column_definitions'
>     /home/lukas/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql/schema_statements.rb:186:in
> `columns'
>     /home/lukas/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/schema_cache.rb:43:in
> `columns'

知道哪里错了吗？

【问题讨论】：

尝试从 Person 中删除 abstract_class，我猜它是试图从 cti_base_class 中获取 table_name 并将其标记为抽象使其为零。

标签： ruby-on-rails ruby inheritance class-table-inheritance

【解决方案1】：

您的Person 类被标记为抽象类，因此它的table_name 是nil。一般来说 abstract_class 已添加，因此 gem 可以定义自己的 ActiveRecord::Base 子类，然后可以在应用程序中继承这些子类，而不会导致 STI 逻辑进入。您可以将其设为非抽象或设置表名以进行继承：

class Person < ActiveRecord::Base
  self.abstract_class = true
  self.table_name = 'people'
  cti_base_class
end

【讨论】：