Invalid use of Null: 'CStr' - checkbox UPDATE - what the heck?!

Question

Jeesh...you just think you're beginning to understand things
and then
something "weird" happens! Anyway, what is wrong with this?:
<input <%If
(CStr((rsCustomer.Fields.Item("deletethis").Value)) =
CStr("True")) Then Response.Write("checked=""checked""") :
Response.Write("")%> name="deletethis" type="checkbox"
id="deletethis"
value="1" />
I have this as part of an UPDATE form. If I place a tick in
the checkbox,
and submit it, it updates the record correctly as having a 1
value (True).
If I open the same UPDATE form, for the same record, it
displays a check in
the check box - great.
However, if the "deletethis" in the user record is initially
"False" (0),
the default value for all of my records, and I submit the
update form
without changing the deletethis checkbox, it seems to be
submitting a blank
value which means that when I re-open the UPDATE form for
this record, and
submit the UPDATE again, I get this:
Error Type:
Microsoft VBScript runtime (0x800A005E)
Invalid use of Null: 'CStr'
//edit-customer.asp, line 838
I'm sure this is because it is trying to submit a blank
value, where it
needs to be either 0 or 1. But why is it submitting
"deletethis" as a blank
value?
When I check my SQL database, the deletethis field shows no
value, not even
the word NULL and certainly not a 1 or 0.
Also, if one of my records already has a 1 value, and I
change this in the
UPDATE form, but "unchecking" the deletethis checkbox, again
it submits a
blank value! Nyaarg!
For reference, here is my UPDATE code:
<%
If (CStr(Request("MM_update")) = "editcontactdetails") Then
If (Not MM_abortEdit) Then
' execute the update
Dim MM_editCmd
Set MM_editCmd = Server.CreateObject ("ADODB.Command")
MM_editCmd.ActiveConnection = MM_connNAME_STRING
MM_editCmd.CommandText = "UPDATE dbo.tblCustomers SET
firstnames = ?,
surname = ?, billbusiness = ?, billaddress = ?, billaddress1
= ?,
billaddress2 = ?, billcity = ?, billregion = ?, billcountry =
billpostcode = ?, billtelephoneday = ?, billmobile = ?,
billtelephoneeve =
?, billemail = ?, billlocationinfo = ?, username = ?,
password = ?,
deletethis = ? WHERE customerID = ?"
MM_editCmd.Prepared = true
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param1", 202,
1, 150, Request.Form("firstnames")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param2", 202,
1, 100, Request.Form("surname")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param3", 202,
1, 150, Request.Form("businessname")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param4", 202,
1, 100, Request.Form("billaddress")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param5", 202,
1, 100, Request.Form("billaddress1")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param6", 202,
1, 100, Request.Form("billaddress2")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param7", 202,
1, 100, Request.Form("billcity")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param8", 5,
1, -1, MM_IIF(Request.Form("billregion"),
Request.Form("billregion"), null))
' adDouble
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param9", 202,
1, 100, Request.Form("billcountry")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param10", 202,
1, 75, Request.Form("billpostcode")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param11", 202,
1, 75, Request.Form("billtelephoneday")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param12", 202,
1, 50, Request.Form("billmobile")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param13", 202,
1, 75, Request.Form("billtelephoneeve")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param14", 202,
1, 150, Request.Form("billemail")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param15", 203,
1, 1073741823, Request.Form("billlocationinfo")) '
adLongVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param16", 202,
1, 25, Request.Form("username")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param17", 202,
1, 25, Request.Form("password")) ' adVarWChar
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param18", 5,
1, -1, MM_IIF(Request.Form("deletethis"),
Request.Form("deletethis"), null))
' adDouble
MM_editCmd.Parameters.Append
MM_editCmd.CreateParameter("param19", 5,
1, -1, MM_IIF(Request.Form("MM_recordId"),
Request.Form("MM_recordId"),
null)) ' adDouble
MM_editCmd.Execute
MM_editCmd.ActiveConnection.Close
' append the query string to the redirect URL
Dim MM_editRedirectUrl
MM_editRedirectUrl = "index.asp"
If (Request.QueryString <> "") Then
If (InStr(1, MM_editRedirectUrl, "?", vbTextCompare) = 0)
Then
MM_editRedirectUrl = MM_editRedirectUrl & "?" &
Request.QueryString
Else
MM_editRedirectUrl = MM_editRedirectUrl & "&" &
Request.QueryString
End If
End If
Response.Redirect(MM_editRedirectUrl)
End If
End If
%>
Please, can someone just tell me what it is, because I can't
find an
explanation in the documentation!
Much appreciated
Nath.

Answer 1

Point taken David, ;o) but you must admit that Dreamweaver is
not strictly
marketed as such.
"With Dreamweaver 8, web developers go from start to finish,
creating and
maintaining basic websites to advanced applications that
support best
practices and the latest technologies."
(source:
http://www.adobe.com/uk/products/dreamweaver/)
Oh, and then there's the price tag! :-o
I personally think they could have marketed "Notepad" a
little better! :o)
Nath.
"David Powers" <[email protected]> wrote in message
news:ej25kb$7nv$[email protected]..
> Lionstone wrote:
>> DW offers a helping hand when it comes to database
integration, but you
>> should expect to do the bulk of the work yourself.
Beyond a simple
>> insert/update/delete of a single record in a single
table, it's all up to
>> you.
>
> Hear, hear. If only more people realized that this is
the case, they would
> find Dreamweaver a lot easier to use.
>
> --
> David Powers
> Adobe Community Expert
> Author, "Foundation PHP for Dreamweaver 8" (friends of
ED)
>
http://foundationphp.com/