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POTrouble with checking for null in a SQL Compact query inside and MVC3 project
 

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  1. POTrouble with checking for null in a SQL Compact query inside and MVC3 project
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    <p>I'm working through the SportsStore example from <a href="http://rads.stackoverflow.com/amzn/click/1430234040" rel="nofollow noreferrer">Pro ASP.NET MVC 3 Framework</a>. At the beginning of chapter 8 i'm instructed to edit my ProductController class, adding the .Where line as follows:</p> <pre><code> public ViewResult List(string category, int page = 1) { ProductsListViewModel viewModel = new ProductsListViewModel { Products = repository.Products .Where(p =&gt; category == null || p.Category == category) .OrderBy(p =&gt; p.ProductID) .Skip((page - 1) * PageSize) .Take(PageSize), PagingInfo = new PagingInfo { CurrentPage = page, ItemsPerPage = PageSize, TotalItems = repository.Products.Count() }, CurrentCategory = category }; return View(viewModel); } </code></pre> <p>When I run the code i get the following error:</p> <pre><code>Exception Details: System.Data.SqlServerCe.SqlCeException: The specified argument value for the function is not valid. [ Argument # = 1,Name of function(if known) = isnull ] </code></pre> <p>on the foreach line in the following code block:</p> <pre><code>@model SportsStore.WebUI.Models.ProductsListViewModel @{ ViewBag.Title = "Products"; } @foreach (var p in Model.Products) { Html.RenderPartial("ProductSummary", p); } &lt;div class="pager"&gt; @Html.PageLinks(Model.PagingInfo, x =&gt; Url.Action("List", new {page = x})) &lt;/div&gt; </code></pre> <p>I've searched a good bit and found a lot of references to <a href="https://stackoverflow.com/questions/9188641/whats-is-wrong-with-this-linq-query">this StackOverflow post</a> in multiple places, but changing the query to</p> <pre><code>.Where(p =&gt; category == null ? true : p.Category == category) </code></pre> <p>had no effect.</p> <p>Some basic information:</p> <ul> <li>This is an MVC3 project using the Razer view engine and C#.</li> <li>All of the items in my SQL Compact 4.0 database have a category.</li> <li>Commenting out the category == null bit makes the code run just fine.</li> <li>The second version I gave above is what is in the downloadable source code from their site.</li> </ul> <p>It does work without the null checking, but i'm worried that if I just move on i may run into issues later on. Does anyone have any ideas as to how I can fix it?</p>
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    1. USWeston Odom
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    1. COu getting error on which line ?
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      1. POTrouble with checking for null in a SQL Compact query inside and MVC3 project
      1. USYasser
    2. COThe error happens on: @foreach (var p in Model.Products)
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      1. POTrouble with checking for null in a SQL Compact query inside and MVC3 project
      1. USWeston Odom
    3. COI don't know anything about MVC3, but could this be a problem with null / DBNull as you mention SQL Compact Edition (just guessing...)?
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      1. USGorgsenegger
 

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