How to avoid exception of request querystring in vb.net if parameter is not passed

Question

If the parameter variable is not passed then this code throws an exception of "Conversion from string "" to type 'Date' is not valid."

this is my code.

 Public Shared ReadOnly Property Request_projectStartDate() As Date
        Get
            Dim _value As String = Nothing

            If Not HttpContext.Current.Request.QueryString("projectStartDate") Is Nothing Then
                _value = HttpContext.Current.Request.QueryString("projectStartDate").ToString()
            End If

            Return CDate(_value)
        End Get
    End Property

sorry i made a mystake the error is "Conversion from string "" to type 'Date' is not valid." because it is nothing — themhz
– themhz, Commented May 2, 2012 at 10:02
What's your question? _value_ will be Nothing if projectStartDate is not on the query string. — Oded
– Oded, Commented May 2, 2012 at 10:03
how can avoid this exception? "Conversion from string "" to type 'Date' is not valid." Because there is no parameter being passed and the conversion to CDate of nothing throws the exception. Do i need to add a default date there? like 1900/01/01? or is there a way to return nothing ? — themhz
– themhz, Commented May 2, 2012 at 10:06

Kamran Pervaiz · Accepted Answer · 2012-05-02 10:06:25Z

14

You can check what @Massimiliano has reported and one more check

If Request.QueryString.HasKeys() Then

   // Check for specified querystrings...
   If Not String.IsNullOrEmpty(Request.QueryString("projectStartDate")) Then
       // Your logic
   End If

End If

answered May 2, 2012 at 10:06

Kamran Pervaiz

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3 Comments

themhz Over a year ago

the problem is when i convert nothing to cdate actually.

Kamran Pervaiz Over a year ago

You dont have to convert nothing into CDate these 2 checks will make sure that there is something (PerojectStartDate) which you can type case by using cdate. are you still getting error?

themhz Over a year ago

thanx. Correct, i don't need to do cdate. Thanx

Massimiliano Peluso · Accepted Answer · 2012-05-02 10:02:08Z

1

If Not String.IsNullOrEmpty(Request.QueryString("projectStartDate")) Then
    //
End If

answered May 2, 2012 at 10:02

Massimiliano Peluso

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1 Comment

themhz Over a year ago

the problem is when i convert nothing to cdate actually.

AngelaG · Accepted Answer · 2016-05-30 12:57:07Z

0

If Request.QueryString("projectStartDate") IsNot Nothing And Request.QueryString("projectStartDate") <> "" Then

answered May 30, 2016 at 12:57

AngelaG

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