Handling DBNull in an ImageURL

Question

User1210767569 posted

I have a hyperlink, as below, that works unless there is a blank in FS2. This error related to the "DateToSymbol" function. I have tried several things from looking for blanks to DBNull. 

Error: Compiler Error Message: BC30108: 'DBNull' is a type and cannot be used as an expression.

Code:

<asp:HyperLink ID="FS2" runat="server" NavigateUrl='<%# Page.Request.Path + "?reqid=" + Eval("PId") + "&TypeID=FS2"  %>'  imageurl='<%# DateToSymbol(Eval("FS2"))%>'> </asp:HyperLink> 

Code behind:

 Public Function DateToSymbol(ByVal vDateTidy As Date) As String

        If DBNull(vDateTidy) = True Then
            'skip
        Else


            Dim vString As String

            If vDateTidy <= DateTime.Now Then
                vString = "../../images/add_button.png"
            Else
                vString = "../../images/add_button1.png"
            End If

        End If
         End If


        Return vString

    End Function

Answer 1

User-718146471 posted

I think the syntax should actually be:

http://msdn.microsoft.com/en-us/library/system.dbnull.value(v=vs.110).aspx?cs-save-lang=1&cs-lang=vb#code-snippet-2

   If Not DbNull.Value.Equals(row.Item(fieldName)) Then 
      Return CStr(row.Item(fieldName)) & " " 
   Else 
      Return Nothing 
   End If 

Answer 2

User-718146471 posted

Keep in mind this is a direct example, you may want to use the field you specified in the DbNull.Value.Equals(yourvalue)

Answer 3

User-1716253493 posted
If IsDBNull(vDateTidy) Then

Answer 4

User1210767569 posted

Looking good. My final code is:

 Public Function DateToSymbol(ByVal vDateTidy) As String


        If Not DBNull.Value.Equals(vDateTidy) Then
            Dim vString As String

            If vDateTidy <= DateTime.Now Then
                vString = "../../images/add_button.png"
            Else
                vString = "../../images/add_button1.png"
            End If
            Return vString
        Else
            Return Nothing
        End If


    End Function