ASP中的错误代码技巧

March 25,2004

When error coding in ASP it’s not as rich an environment as other environments. I really only reports
that there was an error with some Numbers and Descriptions. There is only a few way's I've found to
report these errors back to the end user. I've seen numerous ways of doing it but found this way the
most graceful.    Remember you have to explicitly check after everything that might cause an error.  The
main ones I've experiences are database openings and recordset openings & updates.  Here is the sample
code I use to check for errors and then redirect them to the error page and record the error into a
database.. Note that all my error checking is done before the <html> header is written so if there is an
error it can redirect the page without getting an error of Heading already written to the client.  If the
html header has been sent to the client you can't do a response.redirect command.

Page 1 A sample Active Server Page form you would use to submit data

<html>

<head>
<title>Enter some data into the field</title>
</head>

<body>

<p>Enter some data into the field.  This form is nothing more than representing a
form you would use in real life to submit some data to an ASP page.   Note this
isn't going to enter the data into database but it will record the error on an Error page
and then the some information about the Error.    </p>

<form method="POST" action="error2.asp" name="form1">
<div align="left"><table border="1" width="340" height="35">
<tr>
<td width="143" height="11">Favorite Computer</td>
<td width="185" height="11"><input type="text" name="T1" size="20"></td>
</tr>
<tr>
<td width="143" height="12">Favorite Game: </td>
<td width="185" height="12"><input type="text" name="T2" size="20"></td>
</tr>
</table>
</div><p>:<input type="submit" value="Submit" name="B1"><input type="reset" value="Reset"
name="B2"></p>
</form>
</body>
</html>

Page 2 the form that is being submitted to and also generates the error that
redirects it to the Standard Error Page (Which is Page 3 in this example)

<%@ Language="vbscript"%>
<%
'Hold the page in memory until response.flush command is issued or the </html> tag is processed.
Response.buffer = True

'This forces the page to continue to process even though there was an error.
On Error Resume Next

'Declare all variables
dim conn
dim rs
set conn = server.createobject("adodb.connection")
conn.open "Example_DSN"

'Standard Error coding if the database won't open an error number will return something else but zero
'I then capture the error number and description and is passed using the querystring method
'Note the description is using the Server.URLEncode function ('This will fill any spaces in the
description with
'the correct HTML code
If err.number <> 0 Then
Response.Redirect "Error3.asp?number=" & err.Number & "&desc=" & Server.URLEncode(err.description)
End If
set rs = server.createobject("adodb.recordset")
rs.open "TableName" conn 3 3
'Explicitly checks to see if there is a problem opening the table
If err.number <> 0 Then
Response.Redirect "Error3.asp?number=" & err.Number & "&desc=" & Server.URLEncode(err.description)
End If

rs.addnew
rs("field1") = request.form("field1")
rs("field2") = request.form("field2")
rs.update

'Explicitly checks to see if there is a problem updating the record
If err.number <> 0 Then
Response.Redirect "Error3.asp?number=" & err.Number & "&desc=" & Server.URLEncode(err.description)
End If
rs.close
conn.close
set rs = nothing
set conn = nothing
%>
<html>
<head>
<title>Records been added</title>
</head>

<body>

<p>Your record has been added to the database!</p>
</body>
</html>

Standard Error coding page I use in most all my apps!  You also could easily create some kind of database
connection and report the errors your getting!

<%@ language="vbscript"%>
<%
'buffers the page on the server
Response.Buffer = True

'Declare variables
dim strNumber
dim strdesc
dim conn
dim rs

'sets a local variable to the connection string
strconn = "DRIVER=Microsoft Access Driver (*.mdb);DBQ=" & Server.MapPath("error.mdb")

'Place values that are in the URL into local variables
strNumber = request("Number")
strDesc = request("Desc")

'Opens the connection string and recordset object to record the error in a database
set conn = server.createobject("adodb.connection")
conn.open strconn
set rs = server.createobject("adodb.recordset")
rs.open "tblError", conn, 2,  2
rs.addnew
rs("ErrNumber") = strNumber
rs("ErrDesc") = strDesc
rs("timeoccurred") = now()
rs.update
rs.movelast

'Puts the generated ID into a local variable
strID = rs("id")
rs.close
set rs = nothing
conn.close
set conn = nothing

'Clear errors collections
err.clear

%> </p>

<html>
<head>
<title>Error page</title>
</head>
<body>

<h1>An Error has occurred</h1>
'Writes out the generated Number that is received from the database
'Idea you also could format an email message with this id to report the error to someone
<h2>Error ID is:<% = strID %></h2>

<h3>The Error Number is:</h3>
<i><% = strNumber %>
</i>

<h3>The Error Description is:</h3>
<i><% = strDesc %>
</i>

<h3>Please report this error to the webmaster</h3>
<b><a href="mailto:webmaster@someurl.com">

<p>Click here to send an email please report the Error Number and Description</a></b> </p>
</body>
</html>