Add additional IQueryable extension methods to ResolveConnectionContextExtensions (#177)

Author: myty

README.md

@@ -213,3 +213,31 @@ Convert a connection item cursor to the `int` index of the item in the set.
 #### `ConnectionUtils.OffsetToCursor(int offset)`
 
 Convert an index offset to a connection cursor.
+
+#### `ResolveConnectionContextExtensions.ToConnection<TSource>(this IResolveConnectionContext context, IQueryable<TSource> items)`
+
+Creates a connection from an IQueryable.
+
+```csharp
+public class Droid
+{
+  public string DroidId { get; set; }
+  public string Name { get; set; }
+  public IQueryable<Droid> Friends { get; set; }
+}
+
+public class DroidType : ObjectGraphType<Droid>
+{
+  public DroidType()
+  {
+    Name = "Droid";
+
+    Field<StringGraphType>("name", "The name of the droid.");
+
+    Connection<DroidType>()
+      .Name("friends")
+      .Resolve(context => context
+        .ToConnection(c.Source.Friends));
+  }
+}
+```

src/GraphQL.Relay.ApiTests/GraphQL.Relay.approved.txt

@@ -149,6 +149,7 @@ namespace GraphQL.Relay.Types
         public int SliceSize { get; }
         public int StartIndex { get; }
         public int TotalCount { get; }
+        public GraphQL.Types.Relay.DataObjects.Connection<TSource> ToConnection() { }
     }
 }
 namespace GraphQL.Relay.Utilities
@@ -174,6 +175,7 @@ namespace GraphQL.Relay.Utilities
     public static class ResolveConnectionContextExtensions
     {
         public static GraphQL.Relay.Utilities.EdgeRange EdgesToReturn(this GraphQL.Builders.IResolveConnectionContext context, int edgeCount) { }
+        public static GraphQL.Types.Relay.DataObjects.Connection<TSource> ToConnection<TSource>(this GraphQL.Builders.IResolveConnectionContext context, System.Linq.IQueryable<TSource> items) { }
         public static GraphQL.Types.Relay.DataObjects.Connection<TSource> ToConnection<TSource>(this GraphQL.Builders.IResolveConnectionContext context, System.Collections.Generic.IEnumerable<TSource> items, int? totalCount = default) { }
     }
     public static class StringExtensions

src/GraphQL.Relay/Types/SliceMetrics.cs

@@ -1,5 +1,6 @@
 using GraphQL.Builders;
 using GraphQL.Relay.Utilities;
+using GraphQL.Types.Relay.DataObjects;
 
 namespace GraphQL.Relay.Types
 {
@@ -106,5 +107,39 @@ int totalCount
 
             StartIndex = edges.StartOffset;
         }
+
+        /// <summary>
+        /// Converts current slice to a <see cref="Connection{TSource}"/>
+        /// </summary>
+        /// <returns></returns>
+        public Connection<TSource> ToConnection()
+        {
+            var edges = Slice
+                .Select(
+                    (item, i) =>
+                        new Edge<TSource>
+                        {
+                            Node = item,
+                            Cursor = ConnectionUtils.OffsetToCursor(StartIndex + i)
+                        }
+                )
+                .ToList();
+
+            var firstEdge = edges.FirstOrDefault();
+            var lastEdge = edges.LastOrDefault();
+
+            return new Connection<TSource>
+            {
+                Edges = edges,
+                TotalCount = TotalCount,
+                PageInfo = new PageInfo
+                {
+                    StartCursor = firstEdge?.Cursor,
+                    EndCursor = lastEdge?.Cursor,
+                    HasPreviousPage = HasPrevious,
+                    HasNextPage = HasNext,
+                }
+            };
+        }
     }
 }

src/GraphQL.Relay/Utilities/ResolveConnectionContextExtensions.cs

@@ -34,6 +34,19 @@ int edgeCount
             );
         }
 
+        /// <summary>
+        /// From the connection context, <see cref="IResolveConnectionContext"/>,
+        /// it creates a <see cref="Connection{TSource}"/> based on the given <see cref="IQueryable{TSource}"/>
+        /// </summary>
+        /// <typeparam name="TSource"></typeparam>
+        /// <param name="context"></param>
+        /// <param name="items"></param>
+        /// <returns></returns>
+        public static Connection<TSource> ToConnection<TSource>(
+            this IResolveConnectionContext context,
+            IQueryable<TSource> items
+        ) => SliceMetrics.Create(items, context).ToConnection();
+
         /// <summary>
         /// From the connection context, <see cref="IResolveConnectionContext"/>,
         /// it creates a <see cref="Connection{TSource}"/> based on the given <see cref="IEnumerable{TSource}"/>
@@ -47,37 +60,6 @@ public static Connection<TSource> ToConnection<TSource>(
             this IResolveConnectionContext context,
             IEnumerable<TSource> items,
             int? totalCount = null
-        )
-        {
-            var metrics = SliceMetrics.Create(
-                items,
-                context,
-                totalCount
-            );
-
-            var edges = metrics.Slice
-                .Select((item, i) => new Edge<TSource>
-                {
-                    Node = item,
-                    Cursor = ConnectionUtils.OffsetToCursor(metrics.StartIndex + i)
-                })
-                .ToList();
-
-            var firstEdge = edges.FirstOrDefault();
-            var lastEdge = edges.LastOrDefault();
-
-            return new Connection<TSource>
-            {
-                Edges = edges,
-                TotalCount = metrics.TotalCount,
-                PageInfo = new PageInfo
-                {
-                    StartCursor = firstEdge?.Cursor,
-                    EndCursor = lastEdge?.Cursor,
-                    HasPreviousPage = metrics.HasPrevious,
-                    HasNextPage = metrics.HasNext,
-                }
-            };
-        }
+        ) => SliceMetrics.Create(items, context, totalCount).ToConnection();
     }
 }