Question

164

Accessing ASP Session Variables with Javascript

rated 0 times [ 166] [ 2] / answers: 1 / hits: 17920 / 13 Years ago, tue, august 9, 2011, 12:00:00

I know I can reference a simple session variable (ie: string) in javascript like this:

var SesVar = '<%= Session(MySessionVariable) %>';

alert(SesVar);

But the problem I have is that I have an ASP.NET generic list object stored in Session.Contents. The object looks like this:

Public Class LetterReason



Private _reasonCode As String

Public Property ReasonCode() As String

    Get

        Return _reasonCode

    End Get

    Set(ByVal value As String)

        _reasonCode = value

    End Set

End Property



Private _reason As String

Public Property Reason() As String

    Get

        Return _reason

    End Get

    Set(ByVal value As String)

        _reason = value

    End Set

End Property

I've stored a list of this object in session contents like so:

Dim lsReasons As New List(Of LetterReason)



lsReasons = MyWCF.Get(reasons)



Session.Contents(lsReasons) = lsReasons

Problem is, when I use the code above (SesVar), it returns this:

System.Collections.Generic.List`1[LetterWriterASP2.ServiceReference1.LetterReason]

Is there any way I can access a list stored in session contents through javascript?

Thanks,

Jason

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shane

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answered 13 Years ago trevionbronsonr · Accepted Answer

The problem is that the evaluation binding tag will automatically call the ToString() method on the whatever it finds in the Session object.

So, if:

var SesVar = '<%= Session(MySessionVariable).ToString() %>';

has a meaningful implementation (e.g. it is a string, or a value type), then you'll get what you expect.

However, in your example, you're storing an instance of the class, LetterReason, for which the default object ToString() virtual method call will return the name of the class.

The answer depends what you want to do with the result. You can't trivially use a .NET object in JavaScript, the data is going over a domain boundary (i.e. out of your .NET website and over the network and then into the DOM of a HTML page).

You will need to serialise it in some way, probably JSON. Use an approach like this: Can you Instantiate an Object Instance from JSON in .NET?

That's if you need all the richness of the class. If you're just looking for specific properties/methods, you could have:

var reasonCode = '<%= ((LetterReason)Session(MySessionVariable)).ReasonCode() %>';

var reason = '<%= ((LetterReason)Session(MySessionVariable)).Reason() %>';

So, here you'll need to cast your session instance to your particular class (plain .net System.Object are stored in the Sessions, giving you maximum flexibility) and then take the property you want.

However, serialising the object from .NET to JSON would be much the best solution, as it's flexible and maintainable.