如何在rails中仅将字段的子字符串呈现为json？

class YourModel < ApplicationRecord
  def as_json(options = {})
    super(options).merge({
      sub_string: your_field[0, 10] # 这里假设你的字段名为your_field，将前10个字符作为子字符串呈现
    })
  end
end

class YourController < ApplicationController
  def show
    your_model = YourModel.find(params[:id])
    render json: your_model, only: [:sub_string]
  end
end