Home/ Questions/Amazing solutions for the an item with the same key has already been added error
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Khadijah Evans
  • 9
Asked: 2022-05-17T12:26:27+00:00 In:

Amazing solutions for the an item with the same key has already been added error

  • 9

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I am working on programs, but I found the following warning message:

[ArgumentException: An item with the same key has already been added.]
System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +52
System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) +9382923 System.Linq.Enumerable.ToDictionary(IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer) +252
System.Linq.Enumerable.ToDictionary(IEnumerable`1 source, Func`2 keySelector, IEqualityComparer`1 comparer) +91
System.Web.Mvc.ModelBindingContext.get_PropertyMetadata() +228 System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor) +392
System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext controllerContext, ModelBindingContext bindingContext) +147
System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Object model) +98
System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +2504
System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +548
System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +473
System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +181
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +830 System.Web.Mvc.Controller.ExecuteCore() +136 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +111
System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +39
System.Web.Mvc.<>c__DisplayClass8.b__4() +65 System.Web.Mvc.Async.<>c__DisplayClass1.b__0() +44 System.Web.Mvc.Async.<>c__DisplayClass8`1.b__7(IAsyncResult _) +42 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +141 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +52
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8836913 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184

Is there any way to stabilize the issue “an item with the same key has already been added”? I read a lot of topics about this, but all of them were trying to install anything. Is this the correct way, or any recommendation for me? Please find the beginning command below:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/XYZ.Master"
  Inherits="System.Web.Mvc.ViewPage<XYZ.Models.Admin.AdminSegmentCommissionsModel>" %>
  <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
  Create
  </asp:Content>
  <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
  <% using (Html.BeginForm()) {%> 
  <div class="box3">
  <div class="userinfo">
  <h3>Admin Segment Commissions</h3>
  </div>
  <div class="buttons-panel">
  <ul>
  <li>
  <input type="submit" value="Save" class="save" />
  </li>
  <li>
  <%:Html.ActionLink("Cancel", "Index", new { controller = "AdminSegmentCommissions" }, new { @class = "cancel" })%>
  <%--<input type="button" value="Cancel" class="cancel" onclick="document.location.href='/AirlineLedgerTransactionReceiver/Index'" />--%>
  </li>
  </ul>
  </div>
  </div>
  <div class="row-1">
  <div class="form-box1 round-corner">
  <div class="form-box1-row">
  <div class="form-box1-row-content float-left">
  <div>
  <label>
  <%: Html.LabelFor(model => model.FromSegmentNumber) %></label>
  <%: Html.TextBoxFor(model => model.FromSegmentNumber) %>
  <%: Html.ValidationMessageFor(model => model.FromSegmentNumber) %>
  </div>
  </div>
  </div>
  </div>
  </div>
  <%} %>
same key has already been added
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2 Answers

  1. Best Answer
    Expert

    The cause: Almost certainly, you have a model with duplicate properties. Perhaps you’re hiding the base property with new.

    The solution: Override the property or use a different name as a workaround.

    • 14

  2. This is the solution I came up with. In my ViewModel, I had a duplicate property that had the same name. One Property was in BaseViewModel, and the other in derived Model. 

    public class BaseviewModel{
 public int UserId { get; set; }
}


 public class Model : BaseViewModel
 {
 public int UserId { get; set; }
 }

    That was the last thing I did. 

    public class BaseviewModel{
 public int UserId { get; set; }
}


public class Model : BaseViewModel
{
 public int User_Id { get; set; }
}

    It is now working perfectly.

    • 21

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