如何使用逗号 gem 创建一个包含两个模型的 CSV 文件？

Question

我想在我的 ruby​​ 3.2.8 应用程序中创建一个 CSV 文件，其中包含两个带有逗号 gem 的模型。也许这个问题的答案是微不足道的，但这是我第一次使用这个宝石。我知道如何根据模型创建文件，但我不知道如何匹配两个。

我有一个意见\参与者\索引：

<%= link_to 'Download CSV', '/participants.csv' %>

控制器：

def index
 @participants = Participant.all
 respond_to do |format|
   format.html # index.html.erb
   format.json { render json: @participants }
   format.csv  { send_data @participants.to_comma }
 end
end

参与者模型：

require 'comma'
class Participant < ActiveRecord::Base
  comma do
    id
    token
  end
end

和字段模型：

require 'comma'
class Field < ActiveRecord::Base
  comma do
   name
   value
   id_participant
  end
end

在我拥有的数据库中：

Participant1 = ["id" => 1 , "token" => "a"]
Participant2 = ["id" => 2 , "token" => "b"] 
Field1= ["id_participant" => 1, "name" => "p1_exams1", "value" =>5]
Field2= ["id_participant" => 1, "name" => "p1_exams2", "value" =>3]
Field3= ["id_participant" => 2, "name" => "p2_exams1", "value" =>2]
Field4= ["id_participant" => 2, "name" => "p2_exams2", "value" =>3]

我想要一个这样的文件：

id   token
 1     a

id_p  name            value
 1   p1_c1_exams1      5
 1   p1_c1_exams2      3

id   token
 2     b

id_p  name            value
 2   p1_c1_exams1      2
 2   p1_c1_exams2      3    

我在控制器中尝试过：

def index
@participants = Participant.all
@fields = Field.all
require 'csv'
csv_string = CSV.generate do |csv|
    @participants.each do |p|
        csv << ["id","token","last_ip_address","start_date","last_transition_date","completion_date","completed","total_time_survey","created_at"]
        csv << [ p.id, p.token , p.last_ip_address, p.start_date, p.last_transition_date, p.completion_date, p.completed, p.total_time_survey, p.created_at]
        @fields.each do |f|
            if String(f.id_participant) == String(p.id)
                csv << ["id","name","value","id_participant","id_survey","created_at"]
                csv << [f.id,f.name, f.insert_value, f.id_participant, f.id_survey, f.created_at]
            end
        end
    end
end


respond_to do |format|
  format.html # index.html.erb
  format.json { render json: @participants }
  format.csv  { send_data csv_string,
    :type => "text/csv; charset=iso-8859-1; header=present",
    :disposition => "attachment; filename=Database.csv" }
end
end

Answer 1

您也可以为此使用 fastercsv 我认为这将帮助你我所理解的你在参与者和字段之间有很多关系我已经写了一些代码你可以根据你的需要自定义它

@participants = Participant.all
  csv_string = FasterCSV.generate do |csv|
     @participants.each do |i|
     csv << ["id","token"]
     csv << [ i.id, i.token ]
     i.fields.each do |j|
      csv << ["id_p","name", "value"]
      csv << [i.id,j.name, j.value]
     end
     end
     end
 send_data csv_string,
          :type => "text/csv; charset=iso-8859-1; header=present",
          :disposition => "attachment; filename=anyName.csv"