Exception Management

Learn Modern ColdFusion <CFML> in 100 Minutes
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Try/Catch/Finally
The CFML language also provides you with a traditional approach to deal with error handling at the code block level.  This is usually a trio of constructs:
try: The try block allows you to demarcate the code to test if it fails or passes (https://cfdocs.org/cftry)
catch : The catch block is executed when the try block fails (https://cfdocs.org/cfcatch)
finally : The finally block executes no matter if the try fails or passes. It is guaranteed to always execute. (https://cfdocs.org/cffinally)
Basically, a try and catch statement attempts some code. If the code fails, CFML will do whatever is in the exception to try to handle it without breaking. Of course, many different types of exceptions can occur, which should sometimes be handled in a different manner than the others.
try{
    // code to try to execute
} catch( any e ) {
    // the any type catches ALL errors from the try above
} catch( myType e ){
    // Catch the `myType` only type of exception
} finally {
    // this code executes no matter what
}
Catch Types
The catch construct can take an any or a custom exception type declared by the CFML engine, Java code or custom exceptions within your code.  This is a great way to be able to intercept for specific exception types and address them differently.
try{
​
} catch( database e ){
​
} catch( template e ){
​
}
Native Exception Types
Some of the exception types found in CFML are the following
application: catches application exceptions
database: catches database exceptions
template: catches ColdFusion page exceptions
security: catches security exceptions
object: catches object exceptions
missingInclude: catches missing include file exceptions
expression: catches expression exceptions
lock: catches lock exceptions
custom_type: catches the specified custom exception type that is defined in a cfthrow tag
 java.lang.Exception: catches Java object exceptions
 searchengine: catches Verity search engine exceptions
 any: catches all exception types
Custom Exception Types
Custom exception types are defined by you the programmer and they can also be intercepted via their defined name.  Let's say that the exception type is "InvalidInteger" then you can listen to it like this:
try{
    throw( type="invalidInteger" );
} catch ( "InvalidInteger" e ){
​
}
Throwing Exceptions
Now that you have seen how to listen to exceptions, let's discover the throw or cfthrow constructs used to throw a developer-specific exception. (https://cfdocs.org/cfthrow)
The throw() function or tag has several attributes:
Type : A custom or CFML core type
Message : Describes the exception event
Detail : A detailed description of the event
errorCode : A custom error code 
extendedInfo : Custom extended information to send in the exception, can be anything
object : Mutually exclusive with the other attributes, usually another exception object or a raw Java exception type.
try {
    throw( message="Oops", detail="xyz", errorCode=12 );
} catch (any e) {
    writeOutput( "Error: " & e.message);
} finally {
    writeOutput( "I run even if no error" );
}
Rethrowing Exceptions
The rethrow or cfrethrow construct allows you to well, rethrow the active exception by preserving all of the exception information and types.  Usually you use rethrow within a catch block after you have done some type of operations on the incoming exception. (https://cfdocs.org/cfrethrow)
try{
	runAroundEachClosures( arguments.suite, arguments.spec );
} catch( any e ){
	rethrow;
} finally {
	runAfterEachClosures( arguments.suite, arguments.spec );
}
​
// Mix In Stub
try{
	// include it
	arguments.targetObject.$include = variables.$include;
	arguments.targetObject.$include( instance.mockBox.getGenerationPath() & tmpFile );
	structDelete( arguments.targetObject, "$include" );
	// Remove Stub
	removeStub( genPath & tmpFile );
} catch( any e ) {
	// Remove Stub
	removeStub( genPath & tmpFile);
	rethrow;
}
​
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Outline
Try/Catch/Finally
Catch Types
Native Exception Types
Custom Exception Types
Throwing Exceptions
Rethrowing Exceptions