I get a large list of data to populate into a jqGrid on my clientside.

List<MyData> lotsOfRecords = getData();

Which I then store in cache, since a lot of people will be using it:

Cache["SharedData"].Add(lotsOfRecords);

This grid allows users to check records for processing. I want to persist which records are checked as a user sorts, filters, pages, etc.

My first thought was to add a property bool Selected { get; set; } to the MyData object, and toggle it whenever someone checks a field. Obviously, that won't work since this is a shared cache. I don't want Joe User checking things that Bill User didn't want checked.

Next idea was to store a Dictionary<int, bool> in session, that maps the id of a record to the checked status. This wasn't bad, but since there is no easy way to combine objects in .NET, I don't see a clean way to send that down to my grid without a clunky anonymous object:

return lotsOfRecords.Select(record => {
     record.Id,
     record.Name,
     ...
     myDictionary[record.Id] // true/false for checked
};

That would be a solution, but I'm hoping there is a cleaner design pattern considering I have a lot of fields in my object and use it in a similar way across a few pages. Any suggestions are welcome. Thanks in advance!

Btw, my current environment is ASP.NET MVC 3 with jQuery/UI and jqGrid.

• c#
• asp.net
• .net
• asp.net-mvc
• session

You may be caching the list, but the selections will need to be user-specific. I would suggest building a list of the selected indices each time the page is posted back, and store the list session.

Here's a function that we're using to remember selections as the user pages through results:

/// <summary>
/// Iterates through items in the grid and updates the selected vendor 
/// list with any selections or deselections on the current page
/// </summary>
private void UpdateSelectedItems()
{
    var selectedVendors = new List<int>();

    foreach (GridItem Item in grdVendors.Items)
    {
        if (Item is GridDataItem)
        {
            int VendorID = (int)((GridDataItem)Item).GetDataKeyValue("SupplierID");
            if (Item.Selected)
            {
                if (!selectedVendors.Contains(VendorID))
                    selectedVendors.Add(VendorID);
                continue;
            }

            selectedVendors.Remove(VendorID);
        }
    }            
}

I'm not sure why you think "combining" objects is tough. You can simply do this:

public class SelectableDataObject
{

   public SelectableDataObject(MyDataObject obj)
   {
      this.DataObject = obj;
   }

   public MyDataObject DataObject { get; private set; }
   public bool Selected {get;set;}

}

Then you can just do this:

return lotsOfRecords.Select(record => {
     return new SelectableDataObject(record){Selected = myDictionary.ContainsKey(record.Id)}
};

Alternatively, in your view model you can have the list of objects and the dictionary as two separate properties, and when you iterate the list of objects in your view to populate your grid, you can check the dictionary if the Id exists and check/uncheck based on that. This way is a bit more clunky, but should work.

Either way, I think your dictionary idea is perfectly fine, the only thing I'd do different is just store the Id's of the ones that are selected, that way you only store a subset for each user.