Чтение только определенные столбцы в CSV-файл с filehelpers

Question

Попытка прочитать только эти колонки моего csv файла: Buyer Fullname, Ship to Address1, Ship to Address2, Ship to City, Ship to State, Ship to Zip, Ship to Country, Item Title, Quantity, Sale Price, Shipping and Handling.

Это мой файл .csv:

Sales Record Number,User Id,Buyer Fullname,Buyer Phone Number,Buyer Email,Buyer Address 1,Buyer Address 2,Buyer City,Buyer State,Buyer Zip,Buyer Country,Item Number,Item Title,Custom Label,Quantity,Sale Price,Shipping and Handling,US Tax,Insurance,Cash on delivery fee,Total Price,Payment Method,Sale Date,Checkout Date,Paid on Date,Shipped on Date,Feedback left,Feedback received,Notes to yourself,PayPal Transaction ID,Shipping Service,Cash on delivery option,Transaction ID,Order ID,Variation Details,Global Shipping Program,Global Shipping Reference ID,Ship To Address 1,Ship To Address 2,Ship To City,Ship To State,Ship To Zip,Ship To Country 

"911","trnkaso","TEDDY ROSCO","(815) 814-7454","trnadfo21@yahoo.com","6300 W Cherry St","","NILES","IL","60454-3406","United States","1115402028","SODIUM HYDROXIDE 50% in a one gallon poly bottle. 4 X 1 GALLON POLY BOTTLES","","2","$25.00","$0.00","$0.00","$0.00","","$100.00","PayPal","Sep-04-15","Sep-04-15","Sep-04-15","","No","","","0FG679030062A","UPS Ground","","1419197650001","","","No","","CHEERY ST","","NILES","IL","60714-3496","United States" 
"912","siscokid8","MARK DWAYNE","(408) 943-1485","rasdfdsaay@siscobreakers.com","2050 Dam Ave","","San Jose","CA","95631-2104","United States","111113402518","LACQUER THINNER IN FIVE GALLON METAL PAIL","","1","$50.00","$10.00","$0.00","$0.00","","$153.00","PayPal","Sep-04-15","Sep-04-15","Sep-04-15","","No","","","23432J195640","UPS Ground","","1419241097001","","","No","","205065 Junction Ave","","San DIEGO","CA","95131-2104","United States" 
"913","richmeltre","RICHIE FULLBRIGHT","(210) 863-36454","rcdasfasdftrevino@treasdfavino6.com","1323 Rosecolored Dr","","York","PA","17655-9185","United States","110829686817","Potassium Permanganate in a five lb container","","1","$35.00","$35.00","$0.00","$0.00","","$70.00","PayPal","Sep-06-15","Sep-06-15","Sep-06-15","","No","","","641682286830F","UPS Ground","","1419745125001","","","No","","ROSE GLASS DR","","York","PA","17244-9175","United States" 

3, record(s) downloaded,from ,Sep-04-15,12:34:03, to ,Sep-06-15,04:10:47 
Seller ID: non@non.com 

Не знаю, как пропустить поля я не хочу и добавить только те поля, которые я хочу. Думаю, я мог бы создать фиктивные поля для чтения в файле csv, а затем выполнить удаление на этих элементах позже, но есть ли способ просто не включать их с самого начала? Кроме того, последние две строки вызовут ошибку, и я думаю, как мне их обрабатывать? Вот только немного моего кода:

using System; 
    using System.Collections.Generic; 
    using System.Linq; 
    using System.Text; 
    using System.Threading.Tasks; 
    using FileHelpers; 

    namespace Ebay 
    { 
     class Program 
     { 
      static void Main() 
      { 
       var engine = new FileHelperEngine<Orders>(); 
       var records = engine.ReadFile("SalesHistory.csv"); 
      } 
     } 
     [DelimitedRecord(",")] 
     [IgnoreEmptyLines] 
     class Orders 
     { 
      public string Name { get; set; } 
      public string AddressLine1 { get; set; } 
      public string AddressLine2 { get; set; } 
      public string City { get; set; } 
      public string State { get; set; } 
      public string Title { get; set; } 
      public string ItemPrice { get; set; } 
      public string ShippingPrice { get; set; } 
      public string Quantity { get; set; } 
      public string PostalCode { get; set; } 


     } 
    } 

До сих пор не в состоянии прочитать файл здесь, как я изменил код:

namespace Ebay 
{ 
    class Program 
    { 
     static void Main() 
     { 
      var engine = new FileHelperEngine<Orders>(); 
      var records = engine.ReadFile("SalesHistory.csv"); 
     } 
    } 
    [DelimitedRecord(",")] 
    [IgnoreEmptyLines] 
    public class Orders 
    { 
     [FieldOrder(1)] 
     private String DummyField1; 

     [FieldOrder(2)] 
     private String DummyField2; 

     [FieldOrder(3)] 
     public string Name { get; set; } 

     [FieldOrder(4)] 
     private String DummyField4; 

     [FieldOrder(5)] 
     private String DummyField5; 

     [FieldOrder(6)] 
     private String DummyField6; 

     [FieldOrder(7)] 
     private String DummyField7; 

     [FieldOrder(8)] 
     private String DummyField8; 

     [FieldOrder(9)] 
     private String DummyField9; 

     [FieldOrder(10)] 
     private String DummyField10; 

     [FieldOrder(11)] 
     private String DummyField11; 

     [FieldOrder(12)] 
     private String DummyField12; 

     [FieldOrder(13)] 
     public string Title { get; set; } 

     [FieldOrder(14)] 
     private String DummyField14; 

     [FieldOrder(15)] 
     public string Quantity { get; set; } 

     [FieldOrder(16)] 
     public string ItemPrice { get; set; } 

     [FieldOrder(17)] 
     public string ShippingPrice { get; set; } 

     [FieldOrder(18)] 
     private String DummyField18; 

     [FieldOrder(19)] 
     private String DummyField19; 

     [FieldOrder(20)] 
     private String DummyField20; 

     [FieldOrder(21)] 
     private String DummyField21; 

     [FieldOrder(22)] 
     private String DummyField22; 

     [FieldOrder(23)] 
     private String DummyField23; 

     [FieldOrder(24)] 
     private String DummyField24; 

     [FieldOrder(25)] 
     private String DummyField25; 

     [FieldOrder(26)] 
     private String DummyField26; 

     [FieldOrder(27)] 
     private String DummyField27; 

     [FieldOrder(28)] 
     private String DummyField28; 

     [FieldOrder(29)] 
     private String DummyField29; 

     [FieldOrder(30)] 
     private String DummyField30; 

     [FieldOrder(31)] 
     private String DummyField31; 

     [FieldOrder(32)] 
     private String DummyField32; 

     [FieldOrder(33)] 
     private String DummyField33; 

     [FieldOrder(34)] 
     private String DummyField34; 

     [FieldOrder(35)] 
     private String DummyField35; 

     [FieldOrder(36)] 
     private String DummyField36; 

     [FieldOrder(37)] 
     private String DummyField37; 

     [FieldOrder(38)] 
     public string AddressLine1 { get; set; } 

     [FieldOrder(39)] 
     public string AddressLine2 { get; set; } 

     [FieldOrder(40)] 
     public string City { get; set; } 

     [FieldOrder(41)] 
     public string State { get; set; } 

     [FieldOrder(42)] 
     public string PostalCode { get; set; } 

     [FieldOrder(43)] 
     public string Country { get; set; } 

    } 

Answer 1

Вы почти там, но вы также должны добавить ИгнорироватьFirst и IgnoreLast атрибуты, я думаю. В противном случае последние две или три строки вызовут ошибку, поскольку для макета не хватает столбцов.

Answer 2

Я не использовал FileHelpers библиотеку. Никогда не нужно. Эти манипуляции нелегко сделать сами. То, что я сделаю, так же просто, как 1-2-3:

1. Прочитайте одну строку за раз;
2. Разделить линию и получить токены;
3. Возьмите только токены, упомянутые в массиве обязательных полей.

Идея заключается в том, чтобы сделать добавление необходимых полей ответственность класса Orders вместо того, чтобы писать логику для него в Main().

В сочетании с кодовым псевдокодом, он будет выглядеть следующим образом:

В главном методе

public static void Main() 
{ 
    //Check the file path and other validations etc.. 

    using (var fileReader = ...) 
    { 
     string line; 
     while ((line = fileReader.ReadLine()) != null) 
     { 
      var tokens = line.Split(","); 
      if (tokens.Length != ExpectedLength) continue; //this will filter the non-matching cases, including the last two lines 
      myOrders.AddRequiredFields(tokens); 
     } 
    } 
} 

В классе Orders

Класс Orders необходимости есть метод, который будет читать только нужные маркеры из всех токенов, которые есть в каждой строке. Это будет:

//The properties like Name, Title, Quantity are already defined in this class 

//Need to define an enum. Good programming practice 

enum OrderFieldNumbers 
{ 
    Buyer_Fullname = 0, 
    Ship_to_Address1, 
    Ship_to_Address2, 
    ..., 
    Name, 
    ..., 
    Title, 
    ... //Until all the fields are mentioned 
}; 

public void AddRequiedFields(string[] tokens) 
{ 
    //Simply add the ONLY THOSE FIELDS that you want to read. 
    Name = tokens[OrderFieldNumbers.Name]; 
    Title = tokens[OrderFieldNumbers.Title]; 
    . 
    . 
    . 
} 

Каждый раз, когда вы хотите прочитать определенные поля, изменять AddRequiredFields в соответствии с вашими потребностями. Вы бы уже перечислили все поля файла csv в свойстве OrderFieldNumbers. Таким образом, вам не нужно запоминать позиции каждого поля. Вы просто называете это имя OrderFieldNumbers.myNeededColumnNumber, и вы его получите.