I can't evaluate the value of a querystring (IF, SELECT CASE, etc) in an ASP.NET page with VB

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hello everyone

I have an ASP.NET page with VB, which receives several parameters in the QueryString from an Android application to perform some calculations, for example:

HTML

http://192.168.100.0:8080/pagina.aspx?med=120

In the code behind the page:

VB

Dim strMedida As String = Request.QueryString("med")

And if I print the value of strMeasure, it shows me the value passed in the request:

VB

Context.Response.Write("La medida es: " & strMedida)

The measure is: 120

But when evaluating the variable with an IF, a SELECT CASE, etc., to do some operation, it doesn't do it. Example:

VB

Dim strRes as String
    Select Case strMedida
        Case "100"
            strRes = "La medida es Sencilla"
        Case "120"
            strRes = "La medida es Semi"
        Case "140"
            strRes = "La medida es Doble"
        Case Else
            strRes = "No hay medida"
    End Select

And if I print the value of strRes, it shows me as if strMeasure had no information. The same happens if I evaluate with Request.QueryString("med"):

VB

Context.Response.Write(strRes)

Terminal

No hay medida

Thank you very much for your help

What I have tried:

I have tried creating each parameter of the QueryString as a Class, a Function that returns the value directly and I have not succeeded.

Thank you very much for your help

Posted 24-Jul-23 16:41pm

Member 3446036

Updated 24-Jul-23 19:14pm

OriginalGriff

v4

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OriginalGriff 25-Jul-23 0:42am

This is an English language site, and we can only accept and answer questions in that language.
I have run this through Google Translate to produce a probably-good version, but you should check it and make sure it does say what you are actually asking.

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OriginalGriff · Answer 1 · 2023-07-24T18:49:00

We can't tell: we don't have access to the app generating the data, or the response it gives. And access to the data is essential to work out what is going on.

At a guess, the value returned to your app is not "120", but has either leading or trailing whitespace (Tabs, spaces, and / or newlines) which menas it does not match the compared strings.
I would use Integer.TryParse[^] to convert the string to a number and compare that instead of blindly accepting the string and comparing it!

Graeme_Grant · Answer 2 · 2023-07-24T19:14:00

Solution 2

I agree with @OriginalGriff. You can check by modifying your code:

VB

Context.Response.Write("La medida es: " & strMedida)

to:

VB

Context.Response.Write($"La medida es: [{strMedida}]")

Now you will see the exact value inside the square braces.

Posted 24-Jul-23 19:14pm

Graeme_Grant