EntityFramework和Linq-to-SQL都试图将一部分在内存中,另一部分在数据库中的查询转换为sql
我得到以下错误:
无法创建的常数值类型"Phoenix.Intranet.Web.ClientSettings.ComponentRole"。只有基元类型(例如Int32,String和Guid'(在此背景下。
我理解错误发生的原因。我不明白的是为什么我的代码会产生错误。我的比较是针对原始类型的。所有的比较都是Guid到Guid。该错误特别指出Guids正常。
错误发生在这一行(朝向底部(:
var vla = (from cir in phoenixEntities.ComponentInRoles
代码:
List<ComponentRole> roles;
using (IMSMembershipEntities entities = new IMSMembershipEntities())
{
roles = (from role1 in entities.Roles
select new ComponentRole{Name = role1.RoleName, RoleId = role1.RoleId} ).ToList();
}
List<Components> componentInRoles;
using (PhoenixEntities phoenixEntities = new PhoenixEntities())
{
phoenixEntities.ContextOptions.LazyLoadingEnabled = false;
componentInRoles = (from component in phoenixEntities.Components
select new Components{Name = component.Name,
ComponentId = component.ComponentId,
//InRoles = (from componentInRole in phoenixEntities.ComponentInRoles
// join role in roles on componentInRole.RoleId equals role.RoleId
// where componentInRole.ComponentId == component.ComponentId
// select new ComponentRole{RoleId = role.RoleId, Name = role.Name})
}
).ToList();
foreach (Components cmpent in componentInRoles)
{
Components cmpent1 = cmpent;
//cmpent.InRoles =
var vla = (from cir in phoenixEntities.ComponentInRoles
join role in roles on cir.RoleId equals role.RoleId
where cir.ComponentId == cmpent1.ComponentId
select role).ToList();
}
}
IN
运算符。
并且由于角色是的IEnumerable的类不是基元类型,因此无法将其转换为SQL查询。
您应该首先从数据库中提取到内存中,然后连接内存中的两个列表。
例如:
var vla = (from cir in phoenixEntities.ComponentInRoles.ToList()
join role in roles on cir.RoleId equals role.RoleId
where cir.ComponentId == cmpent1.ComponentId
select role).ToList();
我希望我能帮助