Conversion from string "" to type 'Date' is not valid

Hey everyone,
I know that there are hundreds of articles online about this same error, but I have been going at this for almost 2 days and it’s time I just started a thread of my own.

In my application, I have a textbox that has a CalendarExtender hooked up to it as shown here;

<asp:TextBox ID="ActualAdmitDate" runat="server"></asp:TextBox>
                            <asp:CalendarExtender ID="Calendarextender2" runat="server" CssClass="calStyle"
                                Enabled="True" Format="MMMM d, yyyy" PopupButtonID="calImg3"
                                TargetControlID="ActualAdmitDate">
                            </asp:CalendarExtender><img id="calImg3" alt="" class="style10" src="Styles/calendar.png" />

I also have more textboxes and controls that take information, but this issue is only happening with the date selections.
Basically, it’s possible that a user doesn’t select a date out of this CalendarExtender textbox, leaving the value as “”

I am trying to figure out how I can either store a Null value or “” in my database if the user doesn’t select a date in the CalendarExtender. Here is the code I am currently using, along with the stored procedure that the values are passed into. Here is one condition of the code being used

The DecDateMade variable is the variable that is throwing the error.

            Dim DecMadeBy As String
            Dim DecDateMade As Date
            Dim DecTimeMade As String
            Dim ContID As String
                Dim ContText As String
                Dim ReferElsewhere As String
                Dim ReferLocation As String
                If B4A.Checked = True Then
                    ReferElsewhere = "Yes"
                    If B4McLean.SelectedIndex <> 0 Then
                        ReferLocation = B4McLean.SelectedValue
                    Else
                        ReferLocation = B4Else.Text
                    End If
                ElseIf B4B.Checked = True Then
                    ReferElsewhere = "No"
                    ReferLocation = "N/A"
                End If
If CheckBoxList1.SelectedValue = "" And CheckBoxList2.SelectedValue = "" And PatNoCriteria.Checked = False And ClosedOther.Checked = False Then

                    DecMadeBy = MadeBy.Text
                    If (DecisionDate.Text = "") Then
                        DecDateMade = Nothing
                    Else
                        DecDateMade = Convert.ToDateTime(DecisionDate.Text)
                    End If
                    If (DecisionTime.Text.ToString = "") Then
                        DecTimeMade = "N/A"
                    Else
                        DecTimeMade = DecisionTime.Text
                    End If
                    ContID = ""
                    ContText = ""
                    AdmDecNoAdmit(DecDateMade, DecTimeMade, DecMadeBy, ContID, ContText, ReferElsewhere, ReferLocation)
End If

Stored Procedure:

    Protected Sub AdmDecNoAdmit(ByVal DecDateMade As Date, ByVal DecTimeMade As String, ByVal NoAdmDecMadeBy As String, ByVal Cont As String, ByVal ContText As String, ByVal ReferElsewhere As String, ByVal ReferLocation As String)
        Dim strSQL As String = "INSERT into NoAdmit(InquiryID_fk,ContID, ContText, ReferElsewhere, ReferLocation, MadeBy, DecisionDate, DecisionTime)VALUES(@InquiryID, @ContID, @ContText, @ReferElsewhere, @ReferLocation, @MadeBy, @DecDateMade, @DecTimeMade)SELECT ID = SCOPE_IDENTITY()"
        Dim myConn As New SqlConnection(StringConnection)
        Dim queryCommand As New SqlCommand

        queryCommand.Connection = myConn

        With queryCommand
            .CommandType = CommandType.Text
            .CommandText = strSQL
            .Parameters.AddWithValue("@InquiryID", Session("NewInquiryID"))
            .Parameters.AddWithValue("@ContID", Cont)
            .Parameters.AddWithValue("@ContText", ContText)
            .Parameters.AddWithValue("@ReferElsewhere", ReferElsewhere)
            .Parameters.AddWithValue("@ReferLocation", ReferLocation)
            .Parameters.AddWithValue("@MadeBy", NoAdmDecMadeBy)
            .Parameters.AddWithValue("@DecDateMade", DecDateMade)
            .Parameters.AddWithValue("@DecTimeMade", DecTimeMade)
            myConn.Open()
            Session("DecID") = .ExecuteScalar()
            Session("DecID") = Convert.ToInt32(Session("DecID"))
            'MsgBox(Session("DecID"), MsgBoxStyle.Critical)
            myConn.Close()
        End With
        queryCommand.Dispose()

        Dim UpdSQL As String = "Update Inquiry SET DecisionMade = 'Do Not Admit', DecisionID='" & Session("DecID") & "' WHERE Inquiry.ID = '" & Session("NewInquiryID") & "'"
        Dim UpdateCommand As New SqlCommand
        UpdateCommand.Connection = myConn
        With UpdateCommand
            .CommandType = CommandType.Text
            .CommandText = UpdSQL
            myConn.Open()
            .ExecuteNonQuery()
            myConn.Close()
        End With
        myConn.Dispose()
        UpdateCommand.Dispose()

    End Sub

Hey!

You should be able to do something like this:



If DecDateMade Is Nothing Then
    queryCommand.Parameters.AddWithValue("@DecDateMade", DBNull) ' Or DBNull.Value depending on the framework, I believe
Else
    queryCommand.Parameters.AddWithValue("@DecDateMade", DecDateMade)
End If



This assumes that your table is setup to allow null values for that date field, though.

Shouldn’t you use DateTime instead of Date object?

I don’t know if the DateTime is required. I usually code in C# and I always use a DateTime, but the OP may be ok with a Date. I was focusing more on how to get a null value in the table. Since the code is setup to pass a Date object set to Nothing if the user didn’t select a date, I’m suggesting using that as a flag and I think the DBNull is what the OP needs.

darkwater, your condition inside the stored procedure worked perfectly. I had to modify a couple things inside my code and variable declartions, but everything is storing perfectly. Also, I believe the syntax for asp.net4 is DBNull.Value, that is storing perfectly for me.
Thanks again to everyone for their help, I couldn’t have gotten this done without you guys.