c# - 查询错误：LINQ to Entities 无法识别方法“System.String ToString()”方法

Question

我必须在编辑页面中选中复选框。为此，我有这样的查询：

var queryFI=(from u in _db.User where u.UserID==id where u.IsActive==1
                             select u);
            var join_queryFI=from r in queryFI join f in _db.Financial on r.FinancialID equals f.FinancialID
                             into c
                             from d in c.DefaultIfEmpty()
                             select new viewpartial
                             {
                               Text = d.FiName,
                               Value = d.FinancialID.ToString(),
                               Selected = d.FinancialID == r.FinancialIntermediaryID ? true : false                              
                             };

            ViewBag.IfcList = join_queryFI.ToList();

我收到一个错误：

LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression

请帮忙

Answer 1

You can use SqlFunctions.StringConvert method instead of ToString

Try this once, SqlFunctions.StringConvert(d.FinancialID)

Answer 2

您可以在执行查询后转换为字符串：

var queryFI = (from u in _db.User
                where u.UserID == id
                where u.IsActive == 1
                select u);
var join_queryFI = from r in queryFI
                    join f in _db.Financial on r.FinancialID equals f.FinancialID
                        into c
                    from d in c.DefaultIfEmpty()
                    select new viewpartial
                    {
                        Text = d.FiName,
                        Value = d.FinancialID,
                        Selected = d.FinancialID == r.FinancialIntermediaryID ? true : false
                    };

ViewBag.IfcList = join_queryFI.ToList().Select(x => new { Text = x.Text, Value = x.Value.ToString(), Selected = x.Selected }).ToList();