Question

我正在创建一个连接表，大致遵循Railscast：http://railscasts.com/episodes/17-habtm-checkboxes-revised?view=asciicast

我无法在对象上设置has_many记录并收到以下错误：

2.0.0p353 :012 > invoice.fly_ids
   (0.9ms)  SELECT "flies".id FROM "flies" INNER JOIN "categorizations" ON "flies"."id" = "categorizations"."fly_id" WHERE "categorizations"."invoice_id" = 1
ActiveRecord::StatementInvalid: PG::Error: ERROR:  operator does not exist: integer = character varying
LINE 1: ...ies" INNER JOIN "categorizations" ON "flies"."id" = "categor...
                                                             ^
HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.
: SELECT "flies".id FROM "flies" INNER JOIN "categorizations" ON "flies"."id" = "categorizations"."fly_id" WHERE "categorizations"."invoice_id" = 1

我无法让它工作，我认为这是因为'Categorizations'表使用的是varchar而不是整数。

我的迁移文件如下：

class CreateCategorizations < ActiveRecord::Migration
  def change
    create_table :categorizations do |t|
      t.integer :user_id
      t.integer :fly_id

      t.timestamps

      add_index :categorizations, :user_id
      add_index :categorizations, :fly_id
    end
  end
end

但是，当我查看创建的数据库表时，：user_id和：fly_id都是varchar

为什么我在迁移文件中指定整数时会将这些字段创建为varchar？

（即使我让它工作，也可能无法解决问题......）

编辑：

用户模型：

class User < ActiveRecord::Base

....
has_many :invoices
....
end

发票型号：

class Invoice < ActiveRecord::Base
  attr_accessible :active
  validates :user_id, presence: true
  belongs_to :user

  has_many :categorizations
  has_many :flies, through: :categorizations
end

发票迁移：

class CreateInvoices < ActiveRecord::Migration
  def change
    create_table :invoices do |t|
      t.boolean :active
      t.integer :user_id

      t.timestamps
    end
    add_index :invoices, :user_id
  end

end

分类模型：

class Categorization < ActiveRecord::Base
  attr_accessible :fly_id, :user_id

  belongs_to :invoice
  belongs_to :fly
end

分类迁移：

class CreateCategorizations < ActiveRecord::Migration
  def change
    create_table :categorizations do |t|
      t.integer :user_id
      t.integer :fly_id

      t.timestamps

      add_index :categorizations, :user_id
      add_index :categorizations, :fly_id
    end
  end
end

飞行模型：

class Fly < ActiveRecord::Base
  attr_accessible :description, :name
  validates :description, :name, presence: true

  has_many :categorizations
  has_many :invoices, through: :categorizations
end

飞行迁移：

class CreateFlies < ActiveRecord::Migration
  def change
    create_table :flies do |t|
      t.string :name
      t.string :description

      t.timestamps
    end
  end
end

Answer 1

<强> HABTM

如果您使用的是HABTM，那么您的表格不需要任何主键（id）：

create_table :invoices_flies, :id => false do |t|
  t.references :user
  t.references :flies
end

has_many：通过

如果您使用has_many :through，您的表格将使用主键，因为它将是自己的模型：

#app/models/user.rb
Class User < ActiveRecord::Base
    has_many :categorizations
    has_many :flies, through: :categorizations
end

#app/models/fly.rb
Class Fly < ActiveRecord::Base
    has_many :categorizations
    has_many :users, through: :categorizations
end

#app/models/categorization.rb
Class Categorization < ActiveRecord::Base
    belongs_to :fly
    belongs_to :user
end

create_table :categorizations do |t|
  t.integer :user_id
  t.integer :fly_id
end

我认为您的问题可能与您的协会结构有关 - 您能否就我们如何设置它们提供一些信息？

数据库字段拒绝为整数 - Rails / Postgres

1 个答案: