From 468df47c221c7caa600f122a653db9e78b3ea017 Mon Sep 17 00:00:00 2001
From: Eric Fleming <eric-fleming18@hotmail.com>
Date: Sat, 20 Apr 2019 21:49:57 -0400
Subject: [PATCH 1/2] Adding a GroupBy specification example

---
 src/ApplicationCore/Interfaces/ISpecification.cs          | 1 +
 src/ApplicationCore/Specifications/BaseSpecification.cs   | 7 +++++++
 .../Specifications/CatalogFilterPaginatedSpecification.cs | 1 +
 src/Infrastructure/Data/SpecificationEvaluator.cs         | 8 +++++---
 4 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/ApplicationCore/Interfaces/ISpecification.cs b/src/ApplicationCore/Interfaces/ISpecification.cs
index a61420f..f67414a 100644
--- a/src/ApplicationCore/Interfaces/ISpecification.cs
+++ b/src/ApplicationCore/Interfaces/ISpecification.cs
@@ -11,6 +11,7 @@ namespace Microsoft.eShopWeb.ApplicationCore.Interfaces
         List<string> IncludeStrings { get; }
         Expression<Func<T, object>> OrderBy { get; }
         Expression<Func<T, object>> OrderByDescending { get; }
+        Expression<Func<T, object>> GroupBy { get; }
 
         int Take { get; }
         int Skip { get; }
diff --git a/src/ApplicationCore/Specifications/BaseSpecification.cs b/src/ApplicationCore/Specifications/BaseSpecification.cs
index 1017f3d..bcf1284 100644
--- a/src/ApplicationCore/Specifications/BaseSpecification.cs
+++ b/src/ApplicationCore/Specifications/BaseSpecification.cs
@@ -16,6 +16,7 @@ namespace Microsoft.eShopWeb.ApplicationCore.Specifications
         public List<string> IncludeStrings { get; } = new List<string>();
         public Expression<Func<T, object>> OrderBy { get; private set; }
         public Expression<Func<T, object>> OrderByDescending { get; private set; }
+        public Expression<Func<T, object>> GroupBy { get; private set; }
 
         public int Take { get; private set; }
         public int Skip { get; private set; }
@@ -43,5 +44,11 @@ namespace Microsoft.eShopWeb.ApplicationCore.Specifications
         {
             OrderByDescending = orderByDescendingExpression;
         }
+
+        protected virtual void ApplyGroupBy(Expression<Func<T, object>> groupByExpression)
+        {
+            GroupBy = groupByExpression;
+        }
+
     }
 }
diff --git a/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs b/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs
index f24b8c6..562492d 100644
--- a/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs
+++ b/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs
@@ -9,6 +9,7 @@ namespace Microsoft.eShopWeb.ApplicationCore.Specifications
                 (!typeId.HasValue || i.CatalogTypeId == typeId))
         {
             ApplyPaging(skip, take);
+            ApplyGroupBy(i => new { i.CatalogType });
         }
     }
 }
diff --git a/src/Infrastructure/Data/SpecificationEvaluator.cs b/src/Infrastructure/Data/SpecificationEvaluator.cs
index 88910d2..f029066 100644
--- a/src/Infrastructure/Data/SpecificationEvaluator.cs
+++ b/src/Infrastructure/Data/SpecificationEvaluator.cs
@@ -1,10 +1,7 @@
 using Microsoft.EntityFrameworkCore;
 using Microsoft.eShopWeb.ApplicationCore.Entities;
 using Microsoft.eShopWeb.ApplicationCore.Interfaces;
-using System;
-using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 
 namespace Microsoft.eShopWeb.Infrastructure.Data
 {
@@ -38,6 +35,11 @@ namespace Microsoft.eShopWeb.Infrastructure.Data
                 query = query.OrderByDescending(specification.OrderByDescending);
             }
 
+            if (specification.GroupBy != null)
+            {
+                query = query.GroupBy(specification.GroupBy).SelectMany(x => x);
+            }
+
             // Apply paging if enabled
             if (specification.isPagingEnabled)
             {

From 0d606d18572a405c76f2e2a05456bdc89a5d4f81 Mon Sep 17 00:00:00 2001
From: Eric Fleming <eric-fleming18@hotmail.com>
Date: Wed, 1 May 2019 19:41:22 -0400
Subject: [PATCH 2/2] Removing the apply in the
 CatalogFilterPaginationSpecification

- This is so I can commit this to the repo as an example.
---
 src/ApplicationCore/Specifications/BaseSpecification.cs          | 1 +
 .../Specifications/CatalogFilterPaginatedSpecification.cs        | 1 -
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ApplicationCore/Specifications/BaseSpecification.cs b/src/ApplicationCore/Specifications/BaseSpecification.cs
index bcf1284..f87b8d5 100644
--- a/src/ApplicationCore/Specifications/BaseSpecification.cs
+++ b/src/ApplicationCore/Specifications/BaseSpecification.cs
@@ -45,6 +45,7 @@ namespace Microsoft.eShopWeb.ApplicationCore.Specifications
             OrderByDescending = orderByDescendingExpression;
         }
 
+        //Not used anywhere at the moment, but someone requested an example of setting this up.
         protected virtual void ApplyGroupBy(Expression<Func<T, object>> groupByExpression)
         {
             GroupBy = groupByExpression;
diff --git a/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs b/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs
index 562492d..f24b8c6 100644
--- a/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs
+++ b/src/ApplicationCore/Specifications/CatalogFilterPaginatedSpecification.cs
@@ -9,7 +9,6 @@ namespace Microsoft.eShopWeb.ApplicationCore.Specifications
                 (!typeId.HasValue || i.CatalogTypeId == typeId))
         {
             ApplyPaging(skip, take);
-            ApplyGroupBy(i => new { i.CatalogType });
         }
     }
 }