CODEWITHSUNDEEP
asp.net-mvc
Billy
Billy

Reputation: 21

Asp.net mvc class reference in session

if I put a custom class in session, then in an action method I get an instance of that class from session, and populate some fields, I noticed that when a different controller gets that class from session, those fields are populated. Even though after the first call didn't save the updated class back in session.

is this typical behavior for session objects?

I thought I had to use keyword 'static' on the class in session for this to happen

thanks

Upvotes: 2

Views: 947

Answers (3)

Darin Dimitrov
Darin Dimitrov

Reputation: 1038780

As your class is a reference type this is the normal behavior. Here's what's happening in memory:

  1. You instantiate an object and put it in session

    var someObj = new SomeObject();
Session["someObj"] = someObj;

    At this stage a new object is created on the heap and Session["someObj"] is pointing to this object.

  2. You retrieve the object from session in controller A and modify some property but you do not call Save:

    var someObj = (SomeObject)Session["someObj"];
someObj.SomeProp = "new value";

    Now someObj is pointing to this same object you created earlier on the heap. As someObj is only a reference you are actually modifying the original object in memory.

  3. You retrieve the object from session in Controller B:

    var someObj = (SomeObject)Session["someObj"];

    Now someObj points to the same memory location which has been modified.

Upvotes: 6

Sayed Ibrahim Hashimi
Sayed Ibrahim Hashimi

Reputation: 44322

Since your session is in memory this is the expected behavior. If you store the session in an external store then you have to save the objects back to the session to get that same behvior. I would try to avoid such development becuase when you do change the store the behavior is totally different.

Upvotes: 0

mrjoltcola
mrjoltcola

Reputation: 20842

is this typical behavior for session objects?

Well yes, but, it is typical of .NET objects in general. You took a reference, so you were changing the original object still pointed to by the session.

Upvotes: 1

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