ruby-on-rails - 如何使用 has_and_belongs_to_many 关系为数据库添加种子

Question

我正在尝试构建一个填充州、县和邮政编码表的种子文件。邮政编码可以存在于多个州和县。县和州包含多个邮政编码。我的州和县种子工作正常，但我在播种 zipper 时遇到问题。当我使用种子文件而不尝试引用关系时，它可以工作，但当我尝试建立连接时收到错误。我假设我只是错误地使用 .create 方法来处理多对多关系。

模型

  class County < ActiveRecord::Base
   belongs_to :state
   has_and_belongs_to_many :zips
  end 

class State < ActiveRecord::Base
    has_many :county
    has_and_belongs_to_many :zips
end 

class Zip < ActiveRecord::Base
  has_and_belongs_to_many :counties
  has_and_belongs_to_many :states
end

迁移

class CreateStates < ActiveRecord::Migration
  def change
    create_table :states do |t|
      t.string :name
      t.string :abbreviation

      t.timestamps
    end
  end
end

class CreateCounties < ActiveRecord::Migration
  def change
    create_table :counties do |t|
      t.string :name
      t.references :state, index: true

      t.timestamps
    end
  end
end

class CreateZips < ActiveRecord::Migration
  def change
    create_table :zips do |t|
      t.string :code
      t.timestamps
    end

    create_table :zips_counties, id: false do |t|
      t.belongs_to :zip
      t.belongs_to :county
    end

    create_table :zips_states, id: false do |t|
      t.belongs_to :zip
      t.belongs_to :state
    end
  end
end

种子文件 - 注意..这不是最终版本，我只是想让任何包含多对多关系的东西发挥作用。 “5”确实存在

County.delete_all
State.delete_all
Zip.delete_all
ActiveRecord::Base.connection.reset_pk_sequence!('states')
ActiveRecord::Base.connection.reset_pk_sequence!('counties')

CSV.foreach("lib/tasks/state_table.csv") do |state|
    name = state[0]
    abbr = state[1]
    State.find_or_create_by!(name: name, abbreviation: abbr)
end

CSV.foreach("lib/tasks/counties.csv") do |county|
    name = county[0]
    state = county[1]
    County.create(name: name, state: State.find_by(abbreviation: state))
end

CSV.foreach("lib/tasks/zip_codes.csv") do |zip|
    code = zip[0]
    county = zip[1]
    state = zip[2]
    #puts state
    if County.find_by(name: county) != nil && County.find_by(name: county).state.abbreviation == state
        #puts State.find_by(abbreviation: state).abbreviation == state
        #puts County.find_by(name: county).state.abbreviation
        #puts State.find_by(abbreviation: state).id
        Zip.create(code: code, state: State.find(5))
    end
end

最后，运行“rake db:seed”时出现错误

ActiveRecord::UnknownAttributeError:未知属性:状态

Answer 1

该错误表明您正在尝试设置 Zip 没有的状态属性。 Zip 有一个名为 states 的集合。我想你想说的是:

Zip.create(code: code, states: [ State.find(5) ])