Dynamic UserControl with DropDownLists - not remembering selected values

[NickThissen]

Hi,

I have a UserControl that contains a number of DropDownList controls. One instance of this control represents a list of favorites of a game for one particular user (favorite weapon, map, gametype, etc).
There's actually two versions: there's also one that just displays the values (with labels instead of dropdowns).

The website is about an entire branch of games, including past and future games, and in each game the favorite weapon, map, gametype, etc, applies, so I came up with the following design.

The profile page for each user should display their favorites for each game. Since in the future new games will come out, I am loading the games from the database. For each game, I am dynamically adding a TabPanel into a TabContainer control, which I got from the AJAX Toolkit controls.
In each of these TabPanels, I then dynamically add a new instance of the favorites UserControl that displays the values.

When I add a game to my database in the future, another TabPanel will automatically show up (albeit with blank values at first) so the user can choose his values for that new game.



Anyway, I hope the setup is clear... If not, just imagine a TabContainer with a bunch of TabPanels, where each TabPanel contains a UserControl. The UserControl contains a number of DropDownLists that the user uses to choose some values from a database.

The UserControl has this code:

public partial class EditFavoritesControl : System.Web.UI.UserControl
    {
        // Fields to hold ALL weapons and maps (from this particular game)
        // that the user can choose from
        private FlagEntityCollection<Weapon> weapons;
        private FlagEntityCollection<Map> maps;
 
        protected void Page_Load(object sender, EventArgs e)
        {
            if (this.Game == null || this.Favorites == null) return;
 
            // Always load all choices into the private fields above, regardless of postback or not
            this.LoadChoices();
            
            
            if (!this.IsPostBack)
            {
                // If it's not a postback, load the values into the DropdownLists
                this.LoadLists();
                
                // Then select the appropriate values based on what is stored in the database for this user
                this.LoadSelections();
            }
        }
 
        public ProfileFavorite Favorites { get; set; }
        public Profile Profile { get; set; }
        public Game Game { get; set; }
 
        private void LoadChoices()
        {
            weapons = WeaponManager.Instance.LoadFromGame(this.Game);
            maps = MapManager.Instance.LoadFromGame(this.Game);
        }
 
        private void LoadLists()
        {
            // Weapons and Maps have properties Name and unique Id (int)
            // The dropdowns should display the name but store the Id as the value
            
            cboWeapons.DataSource = weapons;
            cboWeapons.DataTextField = "Name";
            cboWeapons.DataValueField = "Id";
            cboWeapons.DataBind();
                        
            cboMaps.DataSource = maps;
            cboMaps.DataTextField = "Name";
            cboMaps.DataValueField = "Id";
            cboMaps.DataBind();
        }
 
        private void LoadSelections()
        {
            if (this.Favorites == null) return;
 
            // this.Favorites.Weapon, for example, is the weapon that this user has selected previously as his favorite
            cboWeapons.SelectedValue = this.Favorites.Weapon.Id.ToString();
            cboMaps.SelectedValue = this.Favorites.Map.Id.ToString();
        }
 
        public void Save()
        {
            if (this.Favorites == null)
            {
                // Create new into database
                this.Favorites = new ProfileFavorite();
                this.Favorites.Profile = this.Profile;
                this.Favorites.GameValue = this.Game.Id;
            }
 
            // ERROR HERE!!!
            // The SelectedValue is a string representation of the Id of the selected weapon and map
            // so I convert them to an integer and assign them to the WeaponId / MapId properties 
            // (which in turn load the corresponding Weapon and Map behind the scenes)
            this.Favorites.WeaponId = int.Parse(cboWeapons.SelectedValue);
            this.Favorites.MapId = int.Parse(cboMaps.SelectedValue);
 
            // Finally save it to the database
            ProfileFavoriteManager.Instance.Save(this.Favorites);
        }
    }

When loading the UserControls dynamically into their TabPanels, I set the Game, Profile and Favorites properties which determine from which user and from which game to load the data from.

I then store each of these controls in a List<EditFavoritesControl> which I keep in a Session variable. (this might be important)

When the user clicks OK on the edit page after making his choices, I retrieve the list of edit controls from that Session variable and call the Save method on each of them. I have to store them in a Session variable, because I cannot load them from anywhere else (I cannot re-create them, as that would cause the user's selections to get lost obviously). If I don't store them, they will be lost on postback.

This is where the problem finally occurs: whatever the user has selected in the dropdowns, the SelectedValue in the Save method is always what is was when the page loaded.

For example, if I manually edit the database such that the favorite weapon for a particular user has Id 15, then that weapon is shown when the page loads. Then I can use the dropdown to select a different one. In the Save method after I click OK however, the SelectedValue is... 15.


I've had a problem like this before, it seemed like I was always re-loading the user's previous choice (from the database), regardless of whether there is a postback or not. But I'm not doing that, I'm correctly checking in the Page_Load whether there's a postback or not. If it's a postback, I don't load the dropdowns a second time, and I don't select the user's value a second time.

As far as I understand, this should be correct. At least I'm doing this all the time in other pages and it works there.


Maybe the ViewState isn't stored somehow?

I can see two reasons that this might happen:
- The TabContainer / TabPanel does some funky stuff that keeps my DropdownList selections from updating,
- Storing the entire UserControl (multiple instances) in a Session variable does not store the selected values somehow (it is storing the control instances and its properties (the Game, Profile, etc) but maybe not the selected values in the dropdowns?)

In either case, I have no clue how to fix it...


Any help? Thanks!

[sapator]

Maybe you are getting an autopostback from that tabcontainer your are using and it refreshes the comboboxes?

[NickThissen]

Maybe you are getting an autopostback from that tabcontainer your are using and it refreshes the comboboxes?

That may well be... How do I check if that's the case? And more importantly, what do I do about it?

[gep13]

Hello,

The best suggestion here would be to strip your application back.

Get rid of the TabContainers and TabPanels, just have a straight up set of DropDownLists. Do your thing with loading them up, and test to see whether this works. Try that, then come back and let us know where you have got to.

Gary

[NickThissen]

Hey,

That's basically what I did now, except I just put the dropdowns (basically; the contents of each tab panel) in a new page. Instead of doing the editing in the TabContainer, I now just put an Edit button on each tab panel which leads to that page.

This works fine, so the problem is probably related to the tabContainer... Anyway, I don't really mind this solution, it works equally well I think so I think I'm just going to leave it as it is.

[gep13]

Hmm, that is a little strange. The TabContainer should essentially be a "dumb" element, and I can't think why it would be giving you jip

Gary