具有即时方法列的主动管理自定义索引

Question

我有一个用户模型

class User < ApplicationRecord
has_many :payments, dependent: :destroy
has_many :debts, dependent: :destroy

def balance
@balance = self.payments.sum(:amount) - self.debts.sum(:amount)
end

end

并且我在用户控制器中有索引

index do 
selectable_column
column :id
column :name
column :identity_card
column :address
column :contact
column :balance
column :code
column :created_at
column :updated_at
actions
end

如何使用用户模型上的实例方法在索引上显示余额？

Answer 1

  column 'Balance' do |user|
   user.balance
  end

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