Error Catching with CFERROR and CFCATCH

1
Error Catching with CFERROR and CFCATCH

• Douglas Smith, Application Architect
• TeraTech, Inc.
• Tuesday, October 9, 2001

2
Welcome/Goals

• This presentation is about catching and
  monitoring errors, not general error handling
• Quick Review of CFERROR and CFCATCH
• When to use CFERROR vs. CFCATCH
• Tips and Tricks using CFERROR and CFCATCH

3
Why Catch Errors

• Users don't report errors!
• Users go away if there are errors!
• Client's don't report errors!
• Remote web site (no access to CF log)
• Errors are reported incorrectly (do you remember
  the "exact" error message, sir?")
• Don't know how many errors there really are!
• Higher confidence in your web site.
• Security - Hide errors message from potential
  hackers, so they can't see code or database info

4
How to Catch Errors

• Display on the screen
• Emailing Your Errors to yourself
• Logging Your Errors to a DB or Text file

5
CFERROR

• TypeRequest
• Outdated. Use a global 404 handler for this.
• Can't run CF code.
• TypeException
• Can run ANY cf code!
• TypeMonitor
• Very similar to Exception, except not visible to
  the user.
• TypeValidation
• Used for form validation
• We are mainly concerned with "Exception" type for
  this presentation

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CFERROR Variables

• Error.Diagnostics - Detailed error diagnostics
  from ColdFusion Server.
• Error.MailTo - Email address of administrator who
  should be notified (corresponds to the value set
  in the MAILTO attribute of CFERROR).
• Error.DateTime - Date and time when the error
  occurred.
• Error.Browser - Browser that was running when the
  error occurred.
• Error.GeneratedContent - The failed request's
  generated content .
• Error.RemoteAddress - IP address of the remote
  client.
• Error.HTTPReferer Page from which the client
  accessed the link to the page where the error
  occurred.
• Error.Template - Page being executed when the
  error occurred.
• Error.QueryString - URL query string of the
  client's request.

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CFCATCH

• Type Any (default)
• Type APPLICATION (default)
• Type Database
• Type Template
• Type Security
• Type Object
• Type MissingInclude
• Type Expression
• Type Lock
• Type Custom_type

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CFCATCH Example

• Current example is intended to be used as an
  include.
• Can be setup to be a custom tag or module

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CFCATCH Variables

• CFCATCH.Type - Exception type
• CFCATCH.Message - The exception's diagnostic
  message, if one was provided. If no diagnostic
  message is available, this is an empty string.
• CFCATCH.Detail - A detailed message from the CFML
  interpreter. This message, which contains HTML
  formatting, can help determine which tag threw
  the exception.
• CFCATCH.TagContext - The tag stack the name and
  position of each tag in the tag stack, and the
  full path names of the files that contain the
  tags in the tag stack. See the note that follows
  this list for more information.
• CFCATCH.NativeErrorCode - TYPEDatabase only. The
  native error code associated with this exception.
  Database drivers typically provide error codes to
  assist diagnosis of failing database operations.
  If no error code was provided, the value of
  NativeErrorCode is -1.
• CFCATCH.SQLSTATE - TYPEDatabase only. The
  SQLState associated with this exception. Database
  drivers typically provide error codes to assist
  diagnosis of failing database operations. If no
  SQLState value was provided, the value of
  SQLSTATE is -1.
• CFCATCH.ErrNumber - TYPEExpression only.
  Internal expression error number.
• CFCATCH.MissingFileName - TYPEMissingInclude
  only. Name of the file that could not be
  included.
• CFCATCH.LockName - TYPELock only. The name of
  the affected lock (set to anonymous if the lock
  was unnamed).
• CFCATCH.LockOperation - TYPELock only. The
  operation that failed (set to Timeout, Create
  Mutex, or Unknown).
• CFCATCH.ErrorCode - TYPECustom type only. A
  string error code.
• CFCATCH.ExtendedInfo - TYPEAPPLICATION and
  custom only. A custom error message.

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Other Variables that can be used

• CGI.REMOTE_ADDR
• CGI.HTTP_Referer
• CGI.SCRIPT_NAME
• CGI.HTTP_USER_AGENT
• CGI.SERVER_NAME
• user id if you have a members only site
• Other app variables that tell you stuff

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CFERROR Summary

• Pros
• Global for entire application
• Setup in one location
• Easy!
• When to Use
• When you don't feel like learning about
  CFTRY/CFCATCH
• When you need a quick, global solution
• Tips and Tricks
• Treat like any other page on your CF web site,
  give them a complete menu, etc.
• Can contain custom tags and includes (header,
  footers, etc.)

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CFCATCH Summary

• Pros
• Can handle different exception types differently!
• Can totally hide or ignore errors, as needed.
• When to Use
• You don't want to set the user off on another
  direction.
• You want to handle different errors differently
• You want to throw (and catch) your own errors
• Want to retry a locked database error
• When using Fusebox
• Tips and Tricks
• Treat like an include or module
• Can be used in conjunction with CFERROR
  TypeMonitor
• Use the context array variable!
• Always use TypeAny unless you have a reason not
  to
• If specifying the error type, always use ANY as
  catch all afterwards

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Contact Info

• Douglas Smith, Douglas_at_teratech.com
• http//www.teratech.com
• Source Code http//www.cfug-md.org/meetings.cfm