Question

可能重复：
Return anonymous type from LINQ query?

我使用此方法：

public static ... GetList()
    {
        Entity conn = new Entity();
        var lst = (from PS in conn.PurchaserSpecials
                select new
                {
                    PS.PurchaserID,
                    PS.PurchaserSerial,
                    PS.Purchaser.Address,
                    PS.Purchaser.Fax,
                    PS.Purchaser.NumberEconomic
                }).ToList();
return lst;
    }

不能将var用于输出类型。请帮帮我......

输出方法是什么？

Answer 1

这是您创建的匿名类型的列表。

如果您想要返回一个您知道的类型，请创建一个包含您正在选择的字段的新类（我猜测下面的类型）：

public class Specials
    {
        public int PurchaserID { get; set; }
        public int PurchaserSerial { get; set; }
        public string Address { get; set; }
        public int Fax { get; set; }
        public int NumberEconomic { get; set; }
    }

public static List<Specials> GetList()
    {
        Entity conn = new Entity();
        var lst = (from PS in conn.PurchaserSpecials
                select new Specials
                {
                    PurchaserID =  PS.PurchaserID,
                    PurchaserSerial = PS.PurchaserSerial,
                    Address = PS.Purchaser.Address,
                    Fax = PS.Purchaser.Fax,
                    NumberEconomic = PS.Purchaser.NumberEconomic
                }).ToList();
return lst;
    }

Answer 2

您的LINQ查询生成一个匿名类型，因此不能用作该方法的返回类型，并且调用方法不会知道有关返回类型的任何内容。

解决这个问题的方法是使用动态关键字和动态类型。

你方法的返回类型可以是这样的

public dynamic GetList() {
        return ...;

Answer 3

查询的输出是匿名类型，您不能将其作为参数返回。为简单起见，您可以更好地创建类似于：'PurchaseDetail'的所有属性，并返回如下代码：

public static List<PurchaseDetail> GetList() 
    { 
        Entity conn = new Entity(); 
        var lst = (from PS in conn.PurchaserSpecials 
                select new PurchaseDetail
                { 
                    PurchaserID= PS.PurchaserID, 
                    PurchaserSerial=PS.PurchaserSerial, 
                    Address=PS.Purchaser.Address, 
                    Fax=PS.Purchaser.Fax, 
                    NumberEconomic =PS.Purchaser.NumberEconomic 
                }).ToList(); 
return lst; 
    }

Answer 4

退货类型为List of type Products

public static List<Products> GetList()
{
    Entity conn = new Entity();
    var lst = (from PS in conn.PurchaserSpecials
            select new
            {
                PS.PurchaserID,
                PS.PurchaserSerial,
                PS.Purchaser.Address,
                PS.Purchaser.Fax,
                PS.Purchaser.NumberEconomic
            }).ToList();
    return lst;
}

public class Products
{
    //Properties you are using in the query.
}

什么输出类型这种方法？

4 个答案: