使用LINQ将List <U>转换为List <T>

Question

我有2个类,它们有一些相同的属性.我从第一类库存到列表属性,然后,我想获取一些所需的属性并将它们放入第二类类型的列表中.我已经通过C#制作了强制转换序列并运行正常,但我必须使用LINQ.我试图做一些事但没有好结果.请给我一些建议.

第一类:

   public class ServiceInfo {
    private long _id;
    public long ID {
        get { return this._id; }
        set { _id = value; }
    }

    private string _name;
    public string Name {
        get { return this._name; }
        set { _name = value; }
    }

    private long _qty;
    public long Quantity {
        get { return this._qty; }
        set { _qty = value; }
    }

    private double _amount;
    public double Amount {
        get { return this._amount; }
        set { _amount = value; }
    }

    private string _currency;
    public string Currency {
        get { return this._currency; }
        set { _currency = value; }
    }

    private DateTime? _date;
    public DateTime? Date {
        get { return this._date; }
        set { _date = value; }
    }
}

第二类:

class InvoiceWithEntryInfo {
    private string currencyField;

    private long IdField;
    public long IdIWEI {
        get { return this.IdField; }
        set { IdIWEI = value; }
    }

    private string nameField;
    public string NameIWEI {
        get { return this.nameField; }
        set { NameIWEI = value; }
    }

    private long qtyField;
    public long QuantityIWEI {
        get { return this.qtyField; }
        set { QuantityIWEI = value; }
    }

    private double amountField;
    public double AmountIWEI {
        get { return this.amountField; }
        set { AmountIWEI = value; }
    }

    private DateTime dateField;
    public DateTime? DateIWEI {
        get { return this.dateField; }
        set { DateIWEI = value; }
    }

    public string OwnerIWEI {
        get; set;
    }
}

C#样本运行正常:...

var sil = new List<ServiceInfo>();
var iweil = new List<InvoiceWithEntryInfo>();

...

if (sil != null)
    {
        foreach (ServiceInfo item in sil)
        {
            iweil.Add(new InvoiceWithEntryInfo
                {
                    IdIWEI = item.ID,
                    AmountIWEI = item.Amount,
                    DateIWEI = item.Date
                });
        }

LINQ样本没有运行OK:

            iweilCOPY = sil.ConvertAll<InvoiceWithEntryInfo>(a => (InvoiceWithEntryInfo)a);

            iweilCOPY = sil.FindAll(a => (sil is InvoiceWithEntryInfo)).ConvertAll<InvoiceWithEntryInfo>(a => (InvoiceWithEntryInfo)a);

Answer 1

var iweilCopy = sil.Select(item => new InvoiceWithEntryInfo()
{
  IdWEI = item.Id,
  NameWEI = item.Name,
  ....
}).ToList();

Answer 2

  var iweil = sil.Select(item=> new InvoiceWithEntryInfo {
                 IdIWEI = item.ID,
                 AmountIWEI = item.Amount,
                 DateIWEI = item.Date}).ToList();

Answer 3

您需要一个函数将T实例转换为U实例:

ResultType ConvertMethod(StartType input)

你需要写这个.然后

outputList = inputList.Select(ConvertMethod).ToList();

将它应用于整个输入集合.转换函数可以是内联写入的lambda,但不需要(如果函数具有正确的签名,ConvertMethod那么编译器将正确转换它以传递给它Select).

Answer 4

只需使用选择:

if(sil != null)
{
   var iweil = sil.Select(item=>new InvoiceWithEntryInfo()
            {
                IdIWEI = item.ID,
                AmountIWEI = item.Amount,
                DateIWEI = item.Date
            }).ToList();
}