c# - 如何使用 LINQ 在类中填充集合？

Question

我有以下内容：

     foreach (string applicationName in applicationNames)
     {
     _uow.Applications.Add(
        new Application 
        { 
            Name = applicationName, 
            ModifiedDate = DateTime.Now,
            TestAccounts = (from  testAccountName in testAccountNames
                            select new TestAccount
                            { 
                               Name = testAccountName , 
                               ModifiedDate = DateTime.Now 
                           })
        });
     }

这样做的问题是它在选择时在 VS2012 IDE 中给了我一个错误。这里说：

Error   3   Cannot implicitly convert type 
'System.Collections.Generic.IEnumerable<Relational.Models.TestAccount>' to
'System.Collections.Generic.ICollection<Relational.Models.TestAccount>'.
An explicit conversion exists (are you missing a cast?

这是应用程序类：

public partial class Application
{
    public Application()
    {
        this.TestAccounts = new List<TestAccount>();
    }

    public int ApplicationId { get; set; }
    public string Name { get; set; }
    public virtual byte[] Version { get; set; }
    public System.DateTime ModifiedDate { get; set; }
    public virtual ICollection<TestAccount> TestAccounts { get; set; }
}

Answer 1

Use ToList:

 foreach (string applicationName in applicationNames)
 {
 _uow.Applications.Add(
    new Application 
    { 
        Name = applicationName, 
        ModifiedDate = DateTime.Now,
        TestAccounts = (from  testAccountName in testAccountNames
                        select new TestAccount
                        { 
                           Name = testAccountName , 
                           ModifiedDate = DateTime.Now 
                       }).ToList()
    });
 }

Answer 2

You need a cast to IList<TestAccount>.

    { 
        Name = applicationName, 
        ModifiedDate = DateTime.Now,
        TestAccounts = (from  testAccountName in testAccountNames
                        select new TestAccount
                        { 
                           Name = testAccountName , 
                           ModifiedDate = DateTime.Now 
                       }).ToList()     // <-- try this
    });