From 01fc1e0956839d03626c681a71d43043265e878e Mon Sep 17 00:00:00 2001
From: Rex Morgan <rex@rexmorgan.net>
Date: Sat, 20 Jun 2026 13:53:13 -0400
Subject: [PATCH] fix: case-sensitive key lookup for IDictionary/Hashtable
 (issue #521)

The DictionaryMemberAccessor was using ChainSegment.LowerInvariant to
index into a non-generic IDictionary (e.g. Hashtable), silently
downcasing the lookup key. This meant uppercase keys like "NAME" could
never be found via {{NAME}}, while lowercase keys resolved incorrectly
for any casing in the template.

The bug was introduced in commit 9d52004 when the string memberName
parameter was replaced with ChainSegment: LowerInvariant was chosen
instead of TrimmedValue. The fix restores the original exact-match
behaviour, which matches Handlebars.js (JS object keys are always
case-sensitive).

Fixes #521

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 source/Handlebars.Test/IssueTests.cs          | 36 +++++++++++++++++++
 .../DictionaryMemberAccessor.cs               |  2 +-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/source/Handlebars.Test/IssueTests.cs b/source/Handlebars.Test/IssueTests.cs
index 31136117..da1511d3 100644
--- a/source/Handlebars.Test/IssueTests.cs
+++ b/source/Handlebars.Test/IssueTests.cs
@@ -733,5 +733,41 @@ public void UnrecognisedExpressionThrowsOutOfMemoryException()
 
             Assert.Throws<HandlebarsCompilerException>(()=> Handlebars.Compile(source));
         }
+
+        // Issue: https://github.com/Handlebars-Net/Handlebars.Net/issues/521
+        // Hashtable with an uppercase key should be accessible using the same-cased expression.
+        // The IDictionary accessor was incorrectly lowercasing the lookup key.
+        [Fact]
+        public void HashtableUppercaseKeyResolvesWithMatchingExpression()
+        {
+            var template = Handlebars.Compile("Hello {{NAME}}");
+            var result = template(new Hashtable { { "NAME", "alice" } });
+            Assert.Equal("Hello alice", result);
+        }
+
+        [Fact]
+        public void HashtableLowercaseKeyStillResolves()
+        {
+            var template = Handlebars.Compile("Hello {{name}}");
+            var result = template(new Hashtable { { "name", "bob" } });
+            Assert.Equal("Hello bob", result);
+        }
+
+        [Fact]
+        public void GenericDictionaryUppercaseKeyUnchanged()
+        {
+            var template = Handlebars.Compile("Hello {{NAME}}");
+            var result = template(new Dictionary<string, string> { { "NAME", "charlie" } });
+            Assert.Equal("Hello charlie", result);
+        }
+
+        [Fact]
+        public void HashtableLookupIsCaseSensitive()
+        {
+            // {{name}} should NOT resolve a key "NAME" — JS objects are case-sensitive
+            var template = Handlebars.Compile("Hello {{name}}");
+            var result = template(new Hashtable { { "NAME", "dave" } });
+            Assert.Equal("Hello ", result);
+        }
     }
 }
\ No newline at end of file
diff --git a/source/Handlebars/MemberAccessors/DictionaryMemberAccessor.cs b/source/Handlebars/MemberAccessors/DictionaryMemberAccessor.cs
index 6255d6df..710f2754 100644
--- a/source/Handlebars/MemberAccessors/DictionaryMemberAccessor.cs
+++ b/source/Handlebars/MemberAccessors/DictionaryMemberAccessor.cs
@@ -12,7 +12,7 @@ public bool TryGetValue(object instance, ChainSegment memberName, out object val
             // Only string keys supported - indexer takes an object, but no nice
             // way to check if the hashtable check if it should be a different type.
             var dictionary = (IDictionary) instance;
-            value = dictionary[memberName.LowerInvariant];
+            value = dictionary[memberName.TrimmedValue];
             return true;
         }
     }