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POlinq to entity framework custom collection class that inherits list(Of T)
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  1. POlinq to entity framework custom collection class that inherits list(Of T)
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    copied!<p>OK, I'm not quite sure how to ask this, but basically I want to create a custom collection class that allows me to have properties on a generic list (Of T) such as:</p> <pre><code>Public ReadOnly Property TotalCalories() As Decimal Get Dim decTotal As Decimal = 0D For Each thisFoodDiaryItem As FoodDiaryItem In Me Dim thisNutValue As NutritionalData = (From nd In thisFoodDiaryItem.Food.NutritionalDatas Where nd.NutritionalDefinitionID = 208).FirstOrDefault If thisFoodDiaryItem.Food.FoodWeights.Count &gt; 0 Then Dim decWeight As Decimal = thisFoodDiaryItem.Food.FoodWeights(0).WeightInGrams If Not thisNutValue Is Nothing Then Dim decCalories As Decimal = Math.Round((thisNutValue.Value * (decWeight / 100)) * thisFoodDiaryItem.Amount) decTotal += decCalories End If End If Next Return decTotal End Get End Property Public ReadOnly Property TotalSugars() As Decimal Get Dim decTotal As Decimal = 0D For Each thisFoodDiaryItem As FoodDiaryItem In Me Dim thisNutValue As NutritionalData = (From nd In thisFoodDiaryItem.Food.NutritionalDatas Where nd.NutritionalDefinitionID = 269).FirstOrDefault If thisFoodDiaryItem.Food.FoodWeights.Count &gt; 0 Then Dim decWeight As Decimal = thisFoodDiaryItem.Food.FoodWeights(0).WeightInGrams If Not thisNutValue Is Nothing Then Dim decCalories As Decimal = Math.Round((thisNutValue.Value * (decWeight / 100)) * thisFoodDiaryItem.Amount) decTotal += decCalories End If End If Next Return decTotal End Get End Property </code></pre> <p>I want this class to be used when calling entity framework queries: </p> <pre><code> Protected Sub BindFoodDiaryItems() CurrentFoodDiaryItems = New FoodDiaryItemCollection CurrentFoodDiaryItems = (From fdi In db.FoodDiaryItems Where fdi.PersonID = CurrentSiteUser.PersonID And fdi.EntryDate = CurrentDiaryDate).ToList If AllMeals Is Nothing Then AllMeals = (From m In db.Meals).ToList End If lvMealsA.DataSource = AllMeals lvMealsA.DataBind() lblTotalCalories.Text = CurrentFoodDiaryItems.TotalCalories.ToString lblTotalSugars.Text = CurrentFoodDiaryItems.TotalSugars.ToString lblTotalFats.Text = CurrentFoodDiaryItems.TotalFat.ToString lblTotalProtein.Text = CurrentFoodDiaryItems.TotalProtein.ToString lblTotalCarbs.Text = CurrentFoodDiaryItems.TotalCarbs.ToString End Sub </code></pre> <p>I'm assuming it would go something like this: </p> <pre><code> Partial Public Class FoodDiaryItemCollection Inherits List(Of FoodDiaryItem) Sub New() End Sub End Class </code></pre> <p>Error I'm getting:</p> <p><strong>Unable to cast object of type 'System.Collections.Generic.List`1[NutritionBridgeModel.FoodDiaryItem]' to type 'NutritionBridgeModel.FoodDiaryItemCollection'.</strong></p> <p>TIA</p>
 

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