错误检查在VBScript NULL [英] Error checking for NULL in VBScript

问题描述

我有下面的VBScript中传统的ASP页：

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

我不断收到关于这行对象需要错误信使如果没有供应商是没有那么。

要么值为NULL，或者它不为空，所以为什么我收到此错误？

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

编辑：如果我调用对象，我通过在为NULL，或者我传递一个字符串

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

推荐答案

从code，它看起来像提供商是一个变体或其他一些变量，不是对象。

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

是Nothing 是唯一的对象，但后来你说这是一个值，要么是NULL或NOT NULL，将由处理ISNULL 。

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.

请尝试使用：

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

另外，如果还是不行，请尝试：

Alternately, if that doesn't work, try:

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

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