CFPARAM | |
Description
Tests for a parameter's existence, tests its data type, and, if a default value is not assigned, provides one. |
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Category
Variable manipulation tags | |
Syntax<cfparam name = "param_name" type = "data_type" default = "value"> | |
See also
cfcookie, cfregistry, cfsavecontent, cfschedule, cfset
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Usage
You can use this tag to make the following tests:
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Example <!--- This example shows how to use CFPARAM to define default values for page variables --------> <cfparam name = "storeTempVar" default = "my default value"> <cfparam name = "tempVar" default = "my default value"> <!--- check if form.tempVar was passed ---> <cfif IsDefined("form.tempVar") is "True"> <!--- check if form.tempVar is not blank ---> <cfif form.tempVar is not ""> <!--- if not, set tempVar to value of form.tempVar ---> <cfset tempVar = form.tempVar> </cfif> </cfif> <body> <h3>cfparam Example</h3> <p>cfparam is used to set default values so thata developer does not have to check for the existence of a variable using a function like IsDefined. <p>The default value of our tempVar is "<cfoutput>#StoreTempVar# </cfoutput>" <!--- check if tempVar is still the same as StoreTempVar and that tempVar is not blank ---> <cfif tempVar is not #StoreTempVar# and tempVar is not ""> <h3>The value of tempVar has changed: the new value is <cfoutput>#tempVar#</cfoutput></h3> </cfif> <p> <form action = "cfparam.cfm" method = "post"> Type in a new value for tempVar, and hit submit:<br> <input type = "Text" name = "tempVar"> <input type = "Submit" name = "" value = "submit"> </form> |
NAME | |
Required | |
Name of parameter to test (such as "Client.Email " or "Cookie.BackgroundColor "). If omitted, and if the parameter does not exist, an error is thrown. |
TYPE | |
Optional | |
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DEFAULT | |
Optional | |
Value to set parameter to if it does not exist. |