ExtraInfo Serialization

When using any of the logging methods like info(), debug(), warn(), etc, they all take two arguments:

  1. The message to log as a string or a closure that returns the message

  2. An extraInfoargument, which can be anything you like.

This extrainfo argument can be a simple value, a CFC, a complex object, or anything you like. The appenders get this extraInfo argument and process it into their appropriate destinations by serializing its value. This is done by using the following algorithm:

  1. If it is a simple value, then use it.

  2. If it is an object, then check if the object has a method called $toString(). If the method exists, then call $toString() and use its return value.

  3. If it's an exception, marshall it to JSON

  4. If it is an object with no $toString() method, marshall its representation into XML format.

  5. If it is a complex variable like a struct, query, array, etc., then marshall it into JSON format.

$toString() Convention

As you can see from the algorithm above, you can use the extraInfo argument to your benefit to save serialized data representations to the appenders and then retrieve or re-inflate them later. The $toString() convention is great because you can control how a CFC will serialize to its string representation. Let's see an example of a simple CFC:

// User.cfc

    function $toString(){
        // return my representation as a comma list of values of my properties
        return "#getName()#,#getAge()#,#getEmail()#";

So when this object is sent to a logger's method, it will detect it is an object, and the $toString() function exists and call it for serialization.

user = userService.getUser( rc.id );

// need to log it.
if( log.canDebug() ){
    log.debug( "User just got logged in right now!", user );

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