Question

我面临一个编译时错误，如

Cannot implicitly convert type 'System.Collections.Generic.List<AnonymousType#1>' to 'System.Collections.Generic.List<AnonymousType#2>'

这是我的代码：

var query = Enumerable.Repeat(new
            {
                        Id = default(int),
                        Name = string.Empty,
                        type_id = default(int),
                        Ownername = string.Empty,
                        Ownermob = string.Empty,
                        ContactPerson = string.Empty,
                        ContactPersonmob = string.Empty,
                        Phone = string.Empty,
                        Mobile = string.Empty,
                        Room = string.Empty,
                        Build = string.Empty,
                        Road = string.Empty,
                        Area = string.Empty,
                        City = string.Empty,
                        country_id = default(int?),
                        state_id = default(int?),
                        Email = string.Empty,
                        Remark = string.Empty,
                        UserOFC = default(bool),
                        UserVAT = default(bool),
                        UserINV = default(bool),
                        UserNone = default(bool),
                        Username = string.Empty,
                        Register_Date = default(DateTime)},0).ToList();

                    query = db.Parties.Where(p => p.type_id.Equals(GroupByENTYPE)).OrderByDescending(p => p.Register_Date).Select(p => new
                    {
                        Id = p.Id,
                        Name = p.Name,
                        type_id = p.type_id,
                        Ownername = p.Ownername,
                        Ownermob = p.Ownermob,
                        ContactPerson = p.ContactPerson,
                        ContactPersonmob = p.ContactPersonmob,
                        Phone = p.Phone,
                        Mobile = p.Mobile,
                        Room = p.Room,
                        Build = p.Build,
                        Road = p.Road,
                        Area = p.Area,
                        City = p.City,
                        country_id = p.country_id,
                        state_id = p.state_id,
                        Email = p.Email,
                        Remark = p.Remark,
                        UserOFC = p.UserOFC,
                        UserVAT = p.UserVAT,
                        UserINV = p.UserINV,
                        UserNone = p.UserNone,
                        Username = db.Users.Where(u => u.Ref_no.Equals(p.User_id)).Select(u => u.Username).FirstOrDefault(),
                        Register_Date = p.Register_Date
                    }).FilterForColumn(ColumnName, SearchText).ToList();//here error occurs
                }

这里用于声明常见查询部分并在多个条件下分配它。在FilterColumn部分编译时遇到错误。如何在另一页上同样的这种声明没有任何问题。

这里我把表格模式提供给知识：

----------------------更新--------------------- -------------------

Id  int Unchecked
Name    varchar(50) Unchecked
type_id int Unchecked
Ownername   varchar(50) Checked
Ownermob    nchar(10)   Checked
Room    varchar(10) Checked
Build   varchar(50) Checked
Road    text    Checked
Area    text    Checked
City    varchar(50) Checked
Phone   nchar(10)   Checked
Mobile  nchar(10)   Checked
Email   varchar(100)    Checked
ContactPerson   varchar(50) Checked
ContactPersonmob    nchar(10)   Checked
UserOFC bit Checked
UserVAT bit Checked
UserINV bit Checked
UserNone    bit Checked
state_id    int Checked
country_id  int Checked
Remark  text    Checked
Register_Date   smalldatetime   Unchecked
User_id char(14)    Unchecked

请帮帮我......

Answer 1

您的匿名类型的属性看起来完全相同，因此我最好的猜测是，您有一个默认类型与您使用对象时使用的实际类型不同。

我认为解决此问题的最佳策略是使用 Null Object pattern

资源：

您可以观看this精彩教程。
Tutorial + example

Answer 2

从纯文本中很难看出来。尝试使用二进制搜索来查找不兼容的属性。那就是

注释掉上半部分属性以查看上半部分属性是否发生不兼容。
如果编译器仍报告错误，请对前半部分属性执行相同操作。
如果编译器没有报告错误，请对后半部分属性执行相同的操作。

无法将类型'System.Collections.Generic.List <anonymoustype＃1>'隐式转换为'System.Collections.Generic.List <anonymoustype＃2>'</anonymoustype＃2> </anonymoustype＃1>

2 个答案: