在 VBScript 中检查 NULL 时出错 [英] Error checking for NULL in VBScript

问题描述

我在经典 ASP 页面中有以下 VBScript:

I have the following VBScript in a Classic ASP page:

function getMagicLink(fromWhere, provider)
    dim url 
    url = "magic.asp?fromwhere=" & fromWhere
    If Not provider is Nothing Then ' Error occurs here
        url = url & "&provider=" & provider 
    End if
    getMagicLink = "<a target='_blank' href='" & url & "'>" & number & "</a>"
end function

我不断收到需要对象"的错误消息，上面写着If Not provider Is Nothing Then.

I keep getting an "Object Required" error messager on the line that says If Not provider Is Nothing Then.

该值要么是 NULL，要么不是 NULL，为什么我会收到这个错误?

Either the value is NULL, or it's not NULL, so why am I getting this error?

当我调用对象时，我传入 NULL，或者传入一个字符串.

When I invoke the object, I pass in either NULL, or I pass in a string.

推荐答案

从你的代码来看，provider 是一个变体或其他一些变量，而不是一个对象.

From your code, it looks like provider is a variant or some other variable, and not an object.

Is Nothing 仅用于对象，但后来你说它是一个应该是 NULL 或 NOT NULL 的值，这将由 IsNull 处理.

Is Nothing is for objects only, yet later you say it's a value that should either be NULL or NOT NULL, which would be handled by IsNull.

尝试使用:

If Not IsNull(provider) Then 
    url = url & "&provider=" & provider 
End if

或者，如果这不起作用，请尝试:

Alternately, if that doesn't work, try:

If provider <> "" Then 
    url = url & "&provider=" & provider 
End if

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