added weight parameter and refactored the quantity to be an int.

GroceriesApi.sln

@@ -3,7 +3,7 @@ Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 16
 VisualStudioVersion = 16.0.29926.136
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "GroceriesApi", "GroceriesApi.csproj", "{E9CD22F4-3E57-4B31-ACF9-2AF695AA5A4C}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "GroceriesApi", "GroceriesApi.csproj", "{E9CD22F4-3E57-4B31-ACF9-2AF695AA5A4C}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

Models/GroceryDueDateModel.cs

@@ -14,5 +14,6 @@ public class GroceryDueDateModel : IGroceryDueDate, IGroceryModel
         public string id { get; set; }
         public string grocery { get; set; }
         public DateTime? sellByDate { get; set; }
+        public string groceryid { get; set; }
     }
 }

Models/GroceryListModel.cs

@@ -15,7 +15,8 @@ public class GroceryListModel : IGroceryListModel
         public string section { get; set; }
         public string brand { get; set; }
         public string grocery { get; set; }
-        public decimal quantity { get; set; }
+        public int quantity { get; set; }
+        public decimal weight { get; set; }
 
     }
 }

Models/GroceryPurchasedModel.cs

@@ -18,10 +18,12 @@ public class GroceryPurchasedModel : IGroceryPurchasedModel
         public GroceryStoreModel store { get; set; }
         public string brand { get; set; }
         public string grocery { get; set; }
-        public decimal quantity { get; set; }
+        public int quantity { get; set; }
+        public decimal weight { get; set; }
         public DateTime date { get; set; }
         public bool onsale { get; set; }
         public DateTime? sellByDate { get; set; }
         public string section { get; set; }
+        public string groceryid { get; set; }
     }
 }

Models/IGroceryDueDate.cs

@@ -1,12 +1,15 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 
 namespace GroceriesApi.Models
 {
     public interface IGroceryDueDate
     {
+        string id { get; set; }
+        string groceryid { get; set; }
         DateTime? sellByDate { get; set; }
     }
 }

Models/IGroceryListModel.cs

@@ -9,6 +9,7 @@ public interface IGroceryListModel : IGroceryModel
         bool onlist { get; set; }
         string section { get; set; }
         string brand { get; set; }
-        decimal quantity { get; set; }
+        int quantity { get; set; }
+        decimal weight { get; set; }
     }
 }

Models/IGroceryPurchasedModel.cs

@@ -4,14 +4,19 @@
 
 namespace GroceriesApi.Models
 {
-    public interface IGroceryPurchasedModel : IGroceryModel, IGroceryDueDate
+    public interface IGroceryPurchasedModel : IGroceryModel
     {
-        decimal itemprice { get; set; }
-        decimal totalprice { get; set; }
-        GroceryStoreModel store { get; set; }
-        DateTime date { get; set; }
-        bool onsale { get; set; }
-        string section { get; set; }
-
+        public string id { get; set; }       
+        public string groceryid { get; set; }
+        public decimal itemprice { get; set; }
+        public decimal totalprice { get; set; }
+        public GroceryStoreModel store { get; set; }
+        public string brand { get; set; }
+        public string section { get; set; }
+        public int quantity { get; set; }
+        public decimal weight { get; set; }
+        public DateTime date { get; set; }
+        public bool onsale { get; set; }
+
     }
 }