IEnumerator实现问题

Question

我有这样的代码：

public class Check21CSVRecord
{

    public string TransactionType;
    public string TransactionCurrency;
    public string Reference;
    public string PaymentType;

    // date of transaction                
    public string TransactionDate;

    public string Notes;

    // customer data goes here
    public string CustomerFirstName;
    public string CustomerInitial;
    public string CustomerLastName;
    public string CustomerStreetAddress;
    public string CustomerCity;
    public string CustomerState;
    public string CustomerZIPCode;

    [FieldConverter(ConverterKind.Date, "MM/dd/yy")] 
    public DateTime CustomerDateBirth;
    public string CustomerCountry;
    public string CustomerEmail;
    public string CustomerPhone;
    public string CustomerIPAddress;

    // MICR line goes here
    public string AuxiliaryOnUs;
    public string ExternalProcessingCode;
    public string PayorBankRoutingNumber;
    public string PayorBankRoutingNumberCheckDigit;
    public string OnUs;

    // check amount
    [FieldConverter(ConverterKind.Double)]
    public double Amount;

    // what account to credit
    public string CreditAccountNumber;

    public string FrontImagePath;
    public string BackImagePath;

    // used to define if we have image or should build it dynamically
    public bool IsDynamicImage{
        get
        {
            return (FrontImagePath.Length == 0 && BackImagePath.Length == 0);
        }
    }
}


public class DataProvider <T>:  IEnumerator
{
    private FileHelperEngine CSVReader;

    private T currentRecord;
    private int currentIndex;
    private string file;
    private T[] collection = new T[5000];

    public DataProvider(string CSVFile)
    {
        CSVReader = new FileHelperEngine(typeof(T));
        collection = CSVReader.ReadFile(file) as T[];

        currentRecord = default(T);            
        file = CSVFile;
        Reset();
    }

    public bool MoveNext()
    {
        if (++currentIndex >= collection.Count())
        {
            return false;
        }
        else
        {   
            currentRecord = collection[currentIndex];
        }
        return true;

    }

    public void Reset()
    {
        currentIndex = -1;
    }

    public void Dispose()
    {

    }

    public T Current
    {
        get
        {
            return currentRecord;
        }
    }

    object System.Collections.IEnumerator.Current
    {
        get { return currentRecord; }
    }
}

当我编译时 - 一切都很好，但是当我调用该类时：

 var input = new DataProvider<Check21CSVRecord>("../../../../Artifacts/IncomingData/Check21/check21.csv");
 while (input.MoveNext())
 {
       Console.WriteLine(input.Current.CustomerFirstName);
 }

我遇到以下问题： http://screencast.com/t/NDBkNTNkMjkt

有什么解决办法吗？

谢谢， 德米特里

Answer 1

您应该首先分配file。

public DataProvider(string CSVFile)
{            
    file = CSVFile;
    CSVReader = new FileHelperEngine(typeof(T));
    collection = CSVReader.ReadFile(file) as T[];

    currentRecord = default(T);
    Reset();
}

Answer 2

是的，因为“file”是空的/null。