Question

我有以下嵌套的视图模型：

Public Class ContentViewModel
    Public Property CONTENTID As Integer
    Public Property IMAGETOCONTENT() As IEnumerable(Of ImageToContentViewModel)
End Class

Public Class ImageToContentViewModel
    Public Property IMAGETOCONTENTID As Integer
    Public Property IMAGE As ImageViewModel
End Class

Public Class ImageViewModel
    Public Property IMAGEID As Integer
    Public Property TITLE As String
End Class

我试图查询嵌套的视图模型：

Function Test() As ContentViewModel
    Dim dataObject = (From a In db.CMS_CONTENT.OfType(Of CMS_EVENT)()
                 Where a.CONTENTID = contentId AndAlso a.DELETED = 0
                 Select New ContentViewModel With {
                     .CONTENTID = a.CONTENTID,                        
                     .IMAGETOCONTENT = (From b In db.CMS_IMAGES_TO_CONTENT
                      Where b.CONTENTID = a.CONTENTID
                      Select New ImageToContentViewModel With {
                          .IMAGETOCONTENTID = b.IMAGETOCONTENTID,
                          .IMAGE = (From c In db.CMS_IMAGES
                                    Where c.IMAGEID = b.IMAGEID And c.DELETED = False
                                    Select New ImageViewModel With {
                                        .IMAGEID = c.IMAGEID,
                                        .TITLE = c.TITLE
                                    })
                      })
                 })

    Return dataObject 
End Function

我的问题是我无法返回填充的viewmodel，因为我总是得到错误：

Type＆＃34; System.Data.Objects.ObjectQuery`1 [MvcApp.ContentViewModel]＆＃34;的对象无法转换为＆＃34; MvcApp.ContentViewModel＆＃34;

Answer 1

您的函数正文创建IQueryable ContentViewModel（实现为System.Data.Objects.ObjectQuery`1[MvcApp.ContentViewModel]），因为这是Select返回的内容。

您应该使用FirstOrDefault()，或将返回类型更改为IQueryable（ContentViewModel）。

查询嵌套Viewmodel的列表

1 个答案: