English 中文(简体)
Invalid Cast Statelessnession. 不详
原标题:Invalid Cast Exception. Not sure why
  • 时间:2011-02-16 21:02:17
  •  标签:
  • vb.net
  • .net

任何人能否从以下职能中看到,为什么我会获得“丧失能力的种姓例外”? 更具体地说,这是“

我试图将一个时间价值从数据库转换为“yyyyMMd”格式的“Sting”,例如,1985年10月22日是“19851022”。

dbReader(fieldName).ToString("yyyyMMdd")

整个职能......

Private Function GetDBReaderDateValue(ByVal dbReader As IDataReader, ByVal fieldName As String) As String

    If dbReader(fieldName) Is DBNull.Value Then
        Return ""
    Else
        Return dbReader(fieldName).ToString("yyyyMMdd")
    End If

End Function
最佳回答

如果<代码>fieldName不是日期,转换将失败。 提一下:

Dim dt As Date
If Date.TryParse(dbReader(fieldName).tostring, dt) Then
     Return dt.ToString("yyyyMMdd")
Else
     Throw New ArgumentException("GetDBReaderDateValue needs a Date-Column as parameter!")
End If
问题回答

似乎请在<代码>上打上<编码>。 目标,且无载荷,以<条码>为单位。 或许需要首先加入<代码>Datetime。





相关问题
Manually implementing high performance algorithms in .NET

As a learning experience I recently tried implementing Quicksort with 3 way partitioning in C#. Apart from needing to add an extra range check on the left/right variables before the recursive call, ...

Anyone feel like passing it forward?

I m the only developer in my company, and am getting along well as an autodidact, but I know I m missing out on the education one gets from working with and having code reviewed by more senior devs. ...

How do I compare two decimals to 10 decimal places?

I m using decimal type (.net), and I want to see if two numbers are equal. But I only want to be accurate to 10 decimal places. For example take these three numbers. I want them all to be equal. 0....

Exception practices when creating a SynchronizationContext?

I m creating an STA version of the SynchronizationContext for use in Windows Workflow 4.0. I m wondering what to do about exceptions when Post-ing callbacks. The SynchronizationContext can be used ...

Show running instance in single instance application

I am building an application with C#. I managed to turn this into a single instance application by checking if the same process is already running. Process[] pname = Process.GetProcessesByName("...

How to combine DataTrigger and EventTrigger?

NOTE I have asked the related question (with an accepted answer): How to combine DataTrigger and Trigger? I think I need to combine an EventTrigger and a DataTrigger to achieve what I m after: when ...

热门标签