ColdFusion isDefined [英] ColdFusion isDefined

问题描述

我试图检查我的表单中是否存在数据如果数据不存在，我想将其分配给O.我如何做。

I am trying to check to see if data exist in my form If data does not exist I want to assign it to O. How can I do this.

<cfif not isDefined("FORM.Age")>
 cfset FORM.Age = "0"
<cfif>

推荐答案

通常最好的做法是避免isDefined 。这是因为isDefined将搜索所有作用域，直到找到匹配的变量。因此，使用structKeyExists更有效率，例如：

Generally the best practice is considered to be to avoid isDefined. This is because isDefined will search all scopes until it finds a matching variable. So it's more efficient to use structKeyExists, eg:

<cfif NOT structKeyExists(form, "age")>
   <cfset form.age = 0>
</cfif>

另外一种方法是使用cfparam，并指定0作为默认值：

Also, another way to achieve this is to use cfparam, and specify 0 as the default:

<cfparam name="form.age" default="0">

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