此上下文中仅支持原始类型或枚举类型- linq join答案

【问题标题】：Only primitive types or enumeration types are supported in this context- linq join此上下文中仅支持原始类型或枚举类型- linq join
【发布时间】：2018-08-27 15:36:00
【问题描述】：

我在尝试加入时收到此错误

var users = _users.Get();
var userApprovals =
(from approval in _entities.ApprovalEntities
join userDetail in users on approval.UserKey equals userDetail.UserId
 where approval.EmployeeUid == employeeUid
 select new UserApproval
{
Id = approval.Id,
EmployeeUid = approval.EmployeeUid,
UserKey = approval.UserKey,
UserId = approval.UserId,
UserName = userDetail.FirstName + " " + userDetail.LastName
}).ToList();

错误此上下文仅支持原始类型或枚举类型

谢谢

【问题讨论】：

标签： linq linq-to-entities

【解决方案1】：

固定， var userApprovals =

(from approval in _entities.ApprovalEntities.ToList()
join userDetail in users on approval.UserKey equals userDetail.UserId
 where approval.EmployeeUid == employeeUid
 select new UserApproval
{
Id = approval.Id,
EmployeeUid = approval.EmployeeUid,
UserKey = approval.UserKey,
UserId = approval.UserId,
UserName = userDetail.FirstName + " " + userDetail.LastName
}).ToList();

【讨论】：

所以你的修复从 ApprovalEntities 表中获取所有记录。这就是你想要的吗？

【解决方案2】：

就我而言，我的问题是使用 IEnumerable 而不使用 toList() 语句。

看，这段代码显示“error Only primitive types or enumeration types are supported in this context”错误：

var query = db.TemplatesDocs.Where(x => x.Id_Template == idTmpl)
        .Join(Utils.DocumentTypes, x => x.Id_Type, y => y.Id, (x, y) => new { tmpDoc = x, type = y } )
        .ToList();

看，这段代码修复了错误：

var query = db.TemplatesDocs.Where(x => x.Id_Template == idTmpl).ToList()
        .Join(Utils.DocumentTypes, x => x.Id_Type, y => y.Id, (x, y) => new { tmpDoc = x, type = y } )
        .ToList();

【讨论】：