variable not being set with value from querystring

Question

I'm trying to pass a GUID variable via the query string. When I run my game, I can see the needed variable in the querystring when it hits the page(planetID):

http://ec2.us-east-2.compute.amazonaws.com/World_Generation/GeneratePlanet.aspx?planetID=3b757g83-f211-1236-a52c-226fw9a9f9d5

However, when I try to display that variable, I get this error in my browser console window(Chrome):

Uncaught ReferenceError: planetID is not defined

Here is my code. You can see that I am declaring the variable 'planetID' and setting it from the query string value:

Partial Public Class PlanetGallery
    Page.Header.DataBind()
    Public planetID As String = ""

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not String.IsNullOrEmpty(Request.QueryString("planetID")) Then planetID = Request.QueryString("planetID")

        ScriptManager.RegisterStartupScript(Page, Me.Page.GetType, "test", "alert('planetID from PlanetGallery_PageLoad Sub' + planetID);", True)
    End Sub

End Class

I'm not sure why it's not working. I think I need another pair of eyes.

If anyone has any suggestions, I'd love to hear them!

Thanks!

where do you get this error? the only error you can get is a javascript error if I see correct — sertsedat
– sertsedat, Commented Apr 17, 2017 at 14:29
@jackjop thanks for asking! I forgot to put that info in there. I've updated my question. I get the error in my browser console window. — SkyeBoniwell
– SkyeBoniwell, Commented Apr 17, 2017 at 14:31
You're not concatenating planetID. You're not passing the value of your planetID VB variable, you're literally passing the string "planetID" to JavaScript. — Tyler Roper
– Tyler Roper, Commented Apr 17, 2017 at 14:31
@Santi I'm sorry, what do you mean? planetID is just a GUID value. Thanks! — SkyeBoniwell
– SkyeBoniwell, Commented Apr 17, 2017 at 14:33
It should be: "alert('planetID from PlanetGallery_PageLoad Sub" & planetID & "');" - If you want the actual value of your variable to get passed, it can't be within quotes. The javascript that you're actually passing in your example is: alert('planetID from PlanetGallery_PageLoad Sub' + planetID); - By passing the word planetID instead of its value, the JavaScript thinks it's a variable. — Tyler Roper
– Tyler Roper, Commented Apr 17, 2017 at 14:34

sertsedat · Accepted Answer · 2017-04-17 14:37:12Z

1

Since you're getting the error at browser console, you should change your code like this:

ScriptManager.RegisterStartupScript(Page, Me.Page.GetType,
      "test", "alert('planetID from PlanetGallery_PageLoad Sub" + planetID + "');", True)

The problem is because javascript cannot access to codebehind variables.

Your javascript is registered like this:

<script>
      alert("planetID from PlanetGallery_PageLoad Sub " + planetID);
</script>

So planetID becomes a variables this way.

answered Apr 17, 2017 at 14:37

sertsedat

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