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DEVELOPING
COLDFUSION 9 APPLICATIONS
Developing CFML Applications
Las
t
upda
te
d 8/5/2010
Handling form field validation errors
When you use server-side form field validation, the default validation error message describes the error cause plainly
and clearly. However, to give the error message a custom look or provide additional information such as service
contact phone numbers and addresses, use the
cferror
tag with the
Validation
attribute in the Application.cfc
initialization code. Or, specify your own validation on the Application.cfm page. An example of such a page is
provided at
Example of a validation error page
section. You can also place form field validation error handling code in
the Application.cfc
onError
method.
Handling compiler exceptions
You cannot handle compiler exceptions directly on the page where they occur, because the exception is caught before
ColdFusion starts running the page code. Fix all compiler exceptions as part of the development process. Use the
reported error message and the code debugging techniques discussed in “
Debugging and Troubleshooting
Applications
” on page 378 to identify and correct the cause of the error.
Compiler exceptions that occur on pages you access by using the
cfinclude
or
cfmessagebox
tags can be handled as
runtime errors by surrounding the
cfinclude
or
cfmodule
tag in a
cftry
block. The compiler exception on the
accessed page gets caught as a runtime error on the base page. However, avoid this "solution" to the problem, as the
correct method for handling compiler errors is to remove them before you deploy the application.
Handling runtime exceptions
You have many choices for handling exceptions, and the exact path you take depends on your application and its
needs. The following table provides a guide to selecting an appropriate technique:
Technique
Use
cftry
Place
cftry
blocks around specific code sections where exceptions can be expected and you want to handle
those exceptions in a context-specific manner; for example, if you want to display an error message that is specific
to that code.
Use
cftry
blocks where you can recover from an exception. For example, you can retry an operation that times
out, or access an alternate resource. You can also use the
cftry
tag to continue processing where a specific
exception does not harm your application; for example, if a missing resource is not required.
For more information, see “
Handling runtime exceptions with ColdFusion tags
” on page
287.
Application.cfc onError
method
Implement the
onError
method in your Application.cfc to consistently handle application-specific exceptions
that are generated by multiple code sections in the application. For more information on error handling using
Application.cfc, see “
Handling errors in Application.cfc
” on page
247.
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