Implementing eager loading for repositories

--HG--
branch : 1.x

src/Orchard/Data/FetchRequest.cs

@@ -0,0 +1,68 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using NHibernate.Linq;
+
+namespace Orchard.Data {
+    public interface IFetchRequest<TQueried, TFetch> : IOrderedQueryable<TQueried> { }
+
+    public static class RepositoryFetchingExtensionMethods {
+        public static IFetchRequest<TOriginating, TRelated> Fetch<TOriginating, TRelated>(this IQueryable<TOriginating> query, Expression<Func<TOriginating, TRelated>> relatedObjectSelector) {
+            var fetch = EagerFetchingExtensionMethods.Fetch(query, relatedObjectSelector);
+            return new FetchRequest<TOriginating, TRelated>(fetch);
+        }
+
+        public static IFetchRequest<TOriginating, TRelated> FetchMany<TOriginating, TRelated>(this IQueryable<TOriginating> query, Expression<Func<TOriginating, IEnumerable<TRelated>>> relatedObjectSelector) {
+            var fecth = EagerFetchingExtensionMethods.FetchMany(query, relatedObjectSelector);
+            return new FetchRequest<TOriginating, TRelated>(fecth);
+        }
+
+        public static IFetchRequest<TQueried, TRelated> ThenFetch<TQueried, TFetch, TRelated>(this IFetchRequest<TQueried, TFetch> query, Expression<Func<TFetch, TRelated>> relatedObjectSelector) {
+            var impl = query as FetchRequest<TQueried, TFetch>;
+            var fetch = EagerFetchingExtensionMethods.ThenFetch(impl.NhFetchRequest, relatedObjectSelector);
+            return new FetchRequest<TQueried, TRelated>(fetch);
+        }
+
+        public static IFetchRequest<TQueried, TRelated> ThenFetchMany<TQueried, TFetch, TRelated>(this IFetchRequest<TQueried, TFetch> query, Expression<Func<TFetch, IEnumerable<TRelated>>> relatedObjectSelector) {
+            var impl = query as FetchRequest<TQueried, TFetch>;
+            var fetch = EagerFetchingExtensionMethods.ThenFetchMany(impl.NhFetchRequest, relatedObjectSelector);
+            return new FetchRequest<TQueried, TRelated>(fetch);
+        }
+    }
+
+    public class FetchRequest<TQueried, TFetch> : IFetchRequest<TQueried, TFetch> {
+        public IEnumerator<TQueried> GetEnumerator() {
+            return this.NhFetchRequest.GetEnumerator();
+        }
+
+        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
+            return this.NhFetchRequest.GetEnumerator();
+        }
+
+        public Type ElementType {
+            get {
+                return this.NhFetchRequest.ElementType;
+            }
+        }
+
+        public Expression Expression {
+            get {
+                return this.NhFetchRequest.Expression;
+            }
+        }
+
+        public IQueryProvider Provider {
+            get {
+                return this.NhFetchRequest.Provider;
+            }
+        }
+
+        public FetchRequest(INhFetchRequest<TQueried, TFetch> nhFetchRequest) {
+            this.NhFetchRequest = nhFetchRequest;
+        }
+
+        public INhFetchRequest<TQueried, TFetch> NhFetchRequest { get; private set; }
+    }
+
+}

src/Orchard/Orchard.Framework.csproj

@@ -171,6 +171,7 @@
     <Compile Include="ContentManagement\QueryHints.cs" />
     <Compile Include="ContentManagement\Utilities\ComputedField.cs" />
     <Compile Include="Data\Bags\SArray.cs" />
+    <Compile Include="Data\FetchRequest.cs" />
     <Compile Include="DisplayManagement\Arguments.cs" />
     <Compile Include="Data\Bags\SConvert.cs" />
     <Compile Include="Data\Bags\Serialization\IBagSerializer.cs" />