From 3940ca8b606e0dd5b3ec229d6caaa047d3f62e03 Mon Sep 17 00:00:00 2001
From: Steve Sanderson <SteveSandersonMS@users.noreply.github.com>
Date: Fri, 26 Jan 2018 09:54:35 -0800
Subject: [PATCH] For components, allow attribute values to be arbitrary
 objects

---
 .../RenderTree/RenderTreeBuilder.cs              | 16 ++++++++++++++--
 .../RenderTree/RenderTreeNode.cs                 |  8 ++++++++
 .../RenderTreeDiffComputerTest.cs                |  8 ++++----
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeBuilder.cs b/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeBuilder.cs
index e9d36b6c81..1969876988 100644
--- a/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeBuilder.cs
+++ b/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeBuilder.cs
@@ -102,8 +102,20 @@ namespace Microsoft.AspNetCore.Blazor.RenderTree
         /// <param name="value">The value of the attribute.</param>
         public void AddAttribute(int sequence, string name, object value)
         {
-            AssertCanAddAttribute();
-            Append(RenderTreeNode.Attribute(sequence, name, value.ToString()));
+            if (_lastNonAttributeNodeType == RenderTreeNodeType.Element)
+            {
+                // Element attribute values can only be strings or UIEventHandler
+                Append(RenderTreeNode.Attribute(sequence, name, value.ToString()));
+            }
+            else if (_lastNonAttributeNodeType == RenderTreeNodeType.Component)
+            {
+                Append(RenderTreeNode.Attribute(sequence, name, value));
+            }
+            else
+            {
+                // This is going to throw. Calling it just to get a consistent exception message.
+                AssertCanAddAttribute();
+            }
         }
 
         /// <summary>
diff --git a/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeNode.cs b/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeNode.cs
index d6351209b9..89399caadb 100644
--- a/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeNode.cs
+++ b/src/Microsoft.AspNetCore.Blazor/RenderTree/RenderTreeNode.cs
@@ -106,6 +106,14 @@ namespace Microsoft.AspNetCore.Blazor.RenderTree
             AttributeValue = value
         };
 
+        internal static RenderTreeNode Attribute(int sequence, string name, object value) => new RenderTreeNode
+        {
+            Sequence = sequence,
+            NodeType = RenderTreeNodeType.Attribute,
+            AttributeName = name,
+            AttributeValue = value
+        };
+
         internal static RenderTreeNode ChildComponent<T>(int sequence) where T: IComponent => new RenderTreeNode
         {
             Sequence = sequence,
diff --git a/test/Microsoft.AspNetCore.Blazor.Test/RenderTreeDiffComputerTest.cs b/test/Microsoft.AspNetCore.Blazor.Test/RenderTreeDiffComputerTest.cs
index 0dd403a544..f341aa7e07 100644
--- a/test/Microsoft.AspNetCore.Blazor.Test/RenderTreeDiffComputerTest.cs
+++ b/test/Microsoft.AspNetCore.Blazor.Test/RenderTreeDiffComputerTest.cs
@@ -684,9 +684,9 @@ namespace Microsoft.AspNetCore.Blazor.Test
             var diff = new RenderTreeDiffComputer(renderer);
             var testObject = new object();
             newTree.OpenComponentElement<FakeComponent>(0);
-            //newTree.AddAttribute(1, nameof(FakeComponent.IntProperty), 123);
+            newTree.AddAttribute(1, nameof(FakeComponent.IntProperty), 123);
             newTree.AddAttribute(2, nameof(FakeComponent.StringProperty), "some string");
-            //newTree.AddAttribute(3, nameof(FakeComponent.ObjectProperty), testObject);
+            newTree.AddAttribute(3, nameof(FakeComponent.ObjectProperty), testObject);
             newTree.CloseElement();
 
             // Act
@@ -696,9 +696,9 @@ namespace Microsoft.AspNetCore.Blazor.Test
             // Assert
             AssertEdit(result.Edits.Single(), RenderTreeEditType.PrependNode, 0);
             Assert.NotNull(componentInstance);
-            //Assert.Equal(123, componentInstance.IntProperty);
+            Assert.Equal(123, componentInstance.IntProperty);
             Assert.Equal("some string", componentInstance.StringProperty);
-            //Assert.Same(testObject, componentInstance.ObjectProperty);
+            Assert.Same(testObject, componentInstance.ObjectProperty);
         }
 
         [Fact]