Serialize iqueryable

I have an ascx user control with and Entity Framework IQueryable property like this:

  public IQueryable<Category> DataSource
    {
        get { return ViewState["Category"] as 开发者_如何学CIQueryable; }
        set { ViewState["Category"] = value; }
    }

As you can see, I tried to use ViewState to persist the value and don't have to set it on every postback but it says type is not marked as serializable...

how can I mark this as serializable?, is it recomendable to save this property on ViewState or is it better to set in on every postback?

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Basically, IQueryable is not serializable because it's not data. The query is like the means to an end, not the end itself.

I would save the result set in the Cache, not ViewState.

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If you absolutely have to save the data in the ViewState you could always serialize it yourself or flatten it in some other way.