c# . net WinForms应用程序:匿名集合-如何设置返回类型

Question

似乎这对我来说是一个恢复问题。当我使用匿名集合时，我再次遇到类型转换的问题。我对XML文件的查询返回字符串值的集合。我试图将这些值从我的数据访问层返回到我的业务逻辑层。提前谢谢。

    public string[] getCustDetails(string customerId)
    {
        //Pulls customer information for selected customer
        var doc = XDocument.Load("Portfolio.xml");
        var custRecord = from account in doc.Descendants("acct")
                         let acct = account.Element("acct")
                         where (string)account.Attribute("custid").Value == customerId
                         select new
                         {
                             Fname = (string)account.Attribute("fname").Value,
                             Lname = (string)account.Attribute("lname").Value,
                             Ssn = (string)account.Attribute("ssn").Value,
                             Dob = (string)account.Attribute("dob").Value,
                             Custid = (string)account.Attribute("custid").Value
                         };
return ?????
    }

Answer 1

匿名类型既不能用作方法的参数，也不能用作返回类型。

我建议用你需要的属性创建一个简单的类，并使用它来代替匿名类型。

public class AccountDetails
{
  public string FName { get; set; }
  public string LName { get; set; }
  public string Ssn { get; set; }
  public string Dob { get; set; }
  public string Custid { get; set; }
}
public IEnumerable<AccountDetails> getCustDetails(string customerId)
{
    //Pulls customer information for selected customer
    var doc = XDocument.Load("Portfolio.xml");
    var custRecords = from account in doc.Descendants("acct")
                     let acct = account.Element("acct")
                     where (string)account.Attribute("custid").Value == customerId
                     select new AccountDetails
                     {
                         Fname = (string)account.Attribute("fname").Value,
                         Lname = (string)account.Attribute("lname").Value,
                         Ssn = (string)account.Attribute("ssn").Value,
                         Dob = (string)account.Attribute("dob").Value,
                         Custid = (string)account.Attribute("custid").Value
                     };
    return custRecords;
}

Answer 2

为需求创建新类，并将其作为列表返回…

    public MyClass[] getCustDetails(string customerId)
    {
        //Pulls customer information for selected customer
        var doc = XDocument.Load("Portfolio.xml");
        var custRecord = (from account in doc.Descendants("acct")
                         let acct = account.Element("acct")
                         where (string)account.Attribute("custid").Value == customerId
                         select new MyClass
                         {
                             Fname = (string)account.Attribute("fname").Value,
                             Lname = (string)account.Attribute("lname").Value,
                             Ssn = (string)account.Attribute("ssn").Value,
                             Dob = (string)account.Attribute("dob").Value,
                             Custid = (string)account.Attribute("custid").Value
                         }).ToArray();
   return custRecord;
    }

将类定义为

public class MyClass
{
    public string Fname  { get; set; }
    public string Lname { get; set; }
    public string Ssn { get; set; }
    public string Dob { get; set; }
    public string Custid { get; set; }
}

Answer 3

我将创建一个包含以下属性的新类。

 string Fname
 string Lname
 string Ssn
 string Dob
 string Custid

然后从getCustDetails()方法返回此类型