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POASP.Net-MVC-3 Beginner problems with ViewModels and submitting them back to the controller
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  1. POASP.Net-MVC-3 Beginner problems with ViewModels and submitting them back to the controller
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    copied!<p>I have build my entities via database-first, since I have to use an existing db.</p> <p>Now, let's say I've got the entity customer and country and I want to edit the customer. My View should contain something like First Name, Last Name and Country which is a DropdownList from all countries in the entity. For that I created a CustomerViewModel which uses these two entities. But I dont' know if all of this is right, since some things don't work.</p> <p>First the code of my CustomerViewModel:</p> <pre><code>public class CustomerViewModel { public CUSTOMER customer { get; set; } public COUNTRY country { get; set; } public IEnumerable&lt;SelectListItem&gt; countryList { get; set; } MyEFEntities db = new MyEFEntities(); public CustomerViewModel(int id) { IEnumerable&lt;CUSTOMER&gt; customerList = from c in db.CUSTOMER where c.CUSTOMERNO== id select c; customer = customerList.First(); var countryListTemp = new List&lt;String&gt;(); var countryListQry = from s in db.COUNTRY select s.COUNTRY_ABBREVIATION; countryListTemp.AddRange(countryListQry); countryList = new SelectList(countryListTemp); } } </code></pre> <p>Then the CustomerController.cs:</p> <pre><code>public ViewResult CustomerData(int id = 0) { // if (id == 0) { ... } var viewModel = new CustomerViewModel(id); return View(viewModel); } [HttpPost] public ActionResult CustomerData(CustomerViewModel model) { db.Entry(model.customer).State = System.Data.EntityState.Modified; db.SaveChanges(); return View(model); } </code></pre> <p>And last but not least the CustomerData.cshtml:</p> <pre><code>@model MyApp.ViewModels.CustomerViewModel @{ ViewBag.Title = "Customer"; } &lt;h2&gt; Customer&lt;/h2&gt; @using (Html.BeginForm("CustomerData", "Customer")) { @Html.ValidationSummary(true) &lt;div id="tabs"&gt; &lt;ul&gt; &lt;li&gt;&lt;a href="#data"&gt;Data&lt;/a&gt;&lt;/li&gt; &lt;li&gt;&lt;a href="#hobbies"&gt;Hobbies&lt;/a&gt;&lt;/li&gt; &lt;li&gt;&lt;a href="#stuff"&gt;Stuff&lt;/a&gt;&lt;/li&gt; &lt;/ul&gt; &lt;div id="data"&gt; &lt;div class="editor-label"&gt; @Html.Encode("Country:") &lt;/div&gt; &lt;div class="editor-field"&gt; @Html.DropDownListFor(m =&gt; m.country.COUNTRY_ABBREVIATION, Model.countryList, Model.customer.ADDRESS.COUNTRY.COUNTRY_ABBREVIATION) &lt;/div&gt; &lt;div class="editor-label"&gt; @Html.Encode("Last name:") @Html.TextBox("lastName", @Model.customer.ADDRESS.NAME) &lt;/div&gt; &lt;div class="editor-label"&gt; @Html.Encode("First Name:") @Html.TextBox("firstName", @Model.customer.ADDRESS.FIRSTNAME) &lt;/div&gt; &lt;/div&gt; &lt;div id="hobbies"&gt; &lt;p&gt; Hobbies &lt;/p&gt; &lt;/div&gt; &lt;div id="stuff"&gt; &lt;p&gt; Stuff &lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;p&gt; &lt;input type="submit" value="Save" /&gt; &lt;/p&gt; } </code></pre> <p>Viewing works great. I get to the URL <a href="http://localhost:12345/Customer/CustomerData/4711" rel="nofollow">http://localhost:12345/Customer/CustomerData/4711</a> and can see the current values for that customer.</p> <p>Now, I'm missing some stuff.</p> <ol> <li><p>The Save-button doesn't work. If I click it, I got an error message, that no parameterless constructor was found for this object. But I want to pass the ViewModel back to the controller. How to overload the Html.BeginForm() method?!</p></li> <li><p>How to I store the changed values from the customer? Is is done by editing the text-fields or do I have to use Html.TextboxFor() instead of Html.Textbox? This is so complicated for a beginner. I'm not into the LINQ style at all.</p></li> <li><p>The Dropdownlist doesn't work as supposed to. The country the customer has already is twice in it. It seems, that the third parameter does not preselct an item but add a default one. Would Html.Dropdownlist be better?</p></li> </ol>
 

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