本文介绍了ColdFusion isDefined的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
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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