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POListbox is null, when passing a query string and processing data on load
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  1. POListbox is null, when passing a query string and processing data on load
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    copied!<p>Hi guys got a wired problem (well I find it a wired problem :P)</p> <p>I have an order page done in asp.net c#, and which a user adds ingredients to a set of list boxes, once the user and finished adding items, they get combined to make a sandwich then added to another list box that shows the sandwiches and their ingredients. I also have a button to allow the user to remove the highlighted sandwich from the order, this all works fine until the page loads up with a query string that skips the adding of ingredients and just shows the sandwiches on a order, the listbox of sandwiches populates fine but I then get an error when the remove button is clicked which is</p> <blockquote> <p>System.NullReferenceException: Object reference not set to an instance of an object.</p> <p>on CompletedSandwiches.SelectedItem.Text</p> </blockquote> <p>the only difference is that I pass a query string "?EDIT=1"</p> <p>and then on page_load I check</p> <pre><code> if (!Page.IsPostBack) { if ((Request.QueryString["EDIT"] != null) &amp;&amp; (Request.QueryString["EDIT"] == "1")) { GetCurrentSandwiches(); } RemoveFilling.Enabled = false; RemoveCondiment.Enabled = false; CID = int.Parse(Session["CID"].ToString()); } </code></pre> <p>GetCurrentSandwiches does the following:</p> <pre><code> protected void GetCurrentSandwiches() { sandwichOnOrder.Clear(); OrderManagement order = new OrderManagement(); List&lt;SarnieIngredients&gt; bob = order.GetSandwichesOnOrder(int.Parse(Session["OID"].ToString())); List&lt;int&gt; ingredientIDs = new List&lt;int&gt;(); foreach (SarnieIngredients sarnie in bob) { List&lt;Ingredients&gt; batchOfIngredients = new List&lt;Ingredients&gt;(); double amount = 0.00; ingredientIDs = sarnie.IngredientIDs; foreach (int i in ingredientIDs) { Ingredients contents = ingredient.GetDesiredIngredientByID(i); batchOfIngredients.Add(contents); amount += contents.Price; } SandwichConentent sandwich = new SandwichConentent(batchOfIngredients, amount); sandwichOnOrder.Add(sandwich); CompletedSandwiches.Items.Add(sandwich.ToString()); } </code></pre> <p>and my remove buttons code does</p> <pre><code> bool found = false; int i = 0; while (i &lt; sandwichOnOrder.Count || found == false) { SandwichConentent content = sandwichOnOrder[i]; if (content.ToString() == CompletedSandwiches.SelectedItem.Text) { CompletedSandwiches.Items.Remove(CompletedSandwiches.SelectedItem); sandwichOnOrder.Remove(content); found = true; } } </code></pre> <p>does anyone have any idea why I am having this problem?</p> <p>thanks in advance Matt</p> <p>edit ~ sorry I forgot to mention I know I haven't put validation in but I check manually that there's a item selected before I pass and when looking at the listbox in debug it is apparently null even though visually it is not. </p> <p>edit 2 ~ sorry again the error occurs on this line</p> <pre><code>if (content.ToString() == CompletedSandwiches.SelectedItem.Text) </code></pre> <p>and when ?EDIT=1 is passed, it is a new page call from the main page of the web app</p>
 

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