asp.net-mvc - 为什么LINQ to Entities无法识别方法'System.String ToString()？

Question

MVC3 Web应用程序内部出现错误。LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression.
当我尝试使用EF从查询中获取值时:

public class DataRepository
    {
        public mydataEntities1 dbContext = new mydataEntities1();

        public List<SelectListItem> GetPricingSecurityID()
        {
        var pricingSecurityID = (from m in dbContext.Reporting_DailyNAV_Pricing
                                     select new SelectListItem
                                         {
                                                Text = m.PricingSecurityID.ToString(),
                                                Value = m.PricingSecurityID.ToString()
                                         });

        return pricingSecurityID.ToList();
        }
    }

Answer 1

那不能转换成SQL。我猜，从理论上讲，它可以，但是没有实现。

得到结果后，只需执行投影即可:

var pricingSecurityID = (from m in dbContext.Reporting_DailyNAV_Pricing
                                     select m.PricingSecurityID).AsEnumerable()
    .Select(x => new SelectListItem{ Text = x.ToString(), Value = x.ToString() });