Question

我首先使用带有EF4.1代码的MVC3 ajaxgrid脚手架，我发现了这个错误：

无法将类型'System.Linq.IQueryable'隐式转换为'System.Data.Objects.ObjectQuery'

错误输入的代码是自动生成的：

public ActionResult GridData(int start = 0, int itemsPerPage = 20, string orderBy = "UserID", bool desc = false)
        {
            Response.AppendHeader("X-Total-Row-Count", repository.Users.Count().ToString());
            ObjectQuery<User> users = (repository as IObjectContextAdapter).ObjectContext.CreateObjectSet<User>();

            users = repository.Users.Include(u => u.Role); //ERROR HERE

            users = users.OrderBy("it." + orderBy + (desc ? " desc" : ""));    
            return PartialView(users.Skip(start).Take(itemsPerPage));
        }

这是用户存储库方法和角色外键

  public IQueryable<Entities.User> Users
        {
            get { return context.Users; }
        }


  public IQueryable<Entities.Role>Roles
        {
            get { return context.Roles; }
        }

我如何解决转换？

Answer 1

摆脱Lambda并使用相关对象：

var users = repository.Users.Include("Role");  //ERROR HERE

假设实体User具有导航属性Role。

Answer 2

原因很清楚：

您拥有users类型ObjectQuery<User>变量，然后指定查询的变量结果IQueryable<User>。

<强>更新请尝试以下代码：

public ActionResult GridData(int start = 0, int itemsPerPage = 20, string orderBy = "UserID", bool desc = false)
{
   Response.AppendHeader("X-Total-Row-Count", repository.Users.Count().ToString());
   //ObjectQuery<User> users = (repository as IObjectContextAdapter).ObjectContext.CreateObjectSet<User>();

   var users = repository.Users.Include(u => u.Role); //ERROR HERE

   users = users.OrderBy("it." + orderBy + (desc ? " desc" : ""));    
   return PartialView(users.Skip(start).Take(itemsPerPage));
}

MVC3 ajaxgrid脚手架错误，无法将类型'System.Linq.IQueryable'隐式转换为'System.Data.Objects.ObjectQuery'

2 个答案: