CFLib.org – Common Function Library Project

Description:
This UDF can be used to get a value from a form, url, or other scope variable depending on its existence. It can also be useful to force a scope precedence that is different from the ColdFusion default. The optional 3rd parameter allows you to define the default return value if is desired.

Return Values:
Returns any possible value.

Example:

<cfset request.testing = "20">
<cfset form.testing = "10">
<cfset url.testing = "5">
<cfset variables.testing = ScopeCoalesce("testing", "client,form,url")>
<cfoutput>
  variables.testing = '#variables.testing#'
</cfoutput>
<!- the output will display '10' ->

Parameters:

Full UDF Source:

/**
 * This UDF will find the first variable scope that exists for a variable in the list of variable scopes and return its value.
 * 
 * @param strVariable      Variable to check for. (Required)
 * @param lstScope      List of scopes to check. (Required)
 * @param default      Default value to use if the variable does not exists. Defaults to an empty string. (Optional)
 * @return Returns any possible value. 
 * @author Scott Jibben (scott@jibben.com) 
 * @version 1, February 17, 2004 
 */
function ScopeCoalesce(strVariable, lstScopes) {
  var vRet = "";
  var nIndex = 1;
  var nLstLen = ListLen(lstScopes);

  // assign the default return if passed in
  If (ArrayLen(Arguments) GTE 3)
    vRet = Arguments[3];

  // loop over the list
  while (nIndex LTE nLstLen) {
    if (IsDefined(ListGetAt(lstScopes, nIndex) & '.' & strVariable)) {
      vRet = Evaluate(ListGetAt(lstScopes, nIndex) & '.' & strVariable);
      break;
    }
    nIndex = nIndex + 1;
  }

  return vRet;
}