From 1565531a2bfcfdd6051706a3fb05d051470b75b2 Mon Sep 17 00:00:00 2001
From: Dmytro Nikitin <dmytro.m.nikitin@gmail.com>
Date: Wed, 5 Aug 2026 20:46:48 +0200
Subject: [PATCH] Fix #2400: AddObjectStatic throwing on null property values

---
 .../Request/PropertyCache.Populator.cs        | 10 ++-
 .../ObjectParameterTests.NullData.cs          | 61 +++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100644 test/RestSharp.Tests/Parameters/ObjectParameterTests.NullData.cs

diff --git a/src/RestSharp/Request/PropertyCache.Populator.cs b/src/RestSharp/Request/PropertyCache.Populator.cs
index 4057ac999..d60885320 100644
--- a/src/RestSharp/Request/PropertyCache.Populator.cs
+++ b/src/RestSharp/Request/PropertyCache.Populator.cs
@@ -74,7 +74,15 @@ internal static Populator From(PropertyInfo property) {
 
             var populate = GetPopulate(getObject, property);
 
-            return new(property.Name, populate);
+            // Skip null property values so a DTO with unset optional properties doesn't throw.
+            // This matches the reflection-based AddObject.
+            return new(
+                property.Name,
+                (model, parameters) => {
+                    if (getObject(model) is null) return;
+                    populate(model, parameters);
+                }
+            );
         }
 
         static Action<T, ICollection<Parameter>> GetPopulate(Func<T, IFormattable> getFormattable, RequestProperty requestProperty)
diff --git a/test/RestSharp.Tests/Parameters/ObjectParameterTests.NullData.cs b/test/RestSharp.Tests/Parameters/ObjectParameterTests.NullData.cs
new file mode 100644
index 000000000..8cc0f4d61
--- /dev/null
+++ b/test/RestSharp.Tests/Parameters/ObjectParameterTests.NullData.cs
@@ -0,0 +1,61 @@
+namespace RestSharp.Tests.Parameters;
+
+public partial class ObjectParameterTests {
+    [Fact]
+    public void AddObjectStatic_skips_null_properties() {
+        var data = new NullableData { Kind = "set" };
+
+        var request = new RestRequest().AddObjectStatic(data);
+
+        request
+            .Parameters
+            .Should()
+            .ContainSingle()
+            .Which
+            .Should()
+            .BeEquivalentTo(new GetOrPostParameter(nameof(NullableData.Kind), "set"));
+    }
+
+    [Fact]
+    public void AddObjectStatic_keeps_non_null_properties_and_skips_null_ones() {
+        var data = new NullableData { Name = "Bob", Age = 30, Link = null, Values = null, Kind = "set" };
+
+        var request = new RestRequest().AddObjectStatic(data);
+
+        request
+            .Parameters
+            .Should()
+            .BeEquivalentTo(new[] {
+                new GetOrPostParameter(nameof(NullableData.Name), "Bob"),
+                new GetOrPostParameter(nameof(NullableData.Age), "30"),
+                new GetOrPostParameter(nameof(NullableData.Kind), "set")
+            });
+    }
+
+    [Fact]
+    public void AddObjectStatic_with_all_null_properties_yields_no_parameters() {
+        var data = new NullableData { Kind = null };
+
+        var request = new RestRequest().AddObjectStatic(data);
+
+        request.Parameters.Should().BeEmpty();
+    }
+
+    [Fact]
+    public void AddObjectStatic_null_property_handling_matches_AddObject() {
+        var data = new NullableData { Name = null, Age = null, Link = null, Values = null, Kind = "set" };
+
+        var objStatic = new RestRequest().AddObjectStatic(data);
+        var reflection = new RestRequest().AddObject(data);
+
+        objStatic.Parameters.Should().BeEquivalentTo(reflection.Parameters);
+    }
+
+    class NullableData {
+        public string Name { get; set; }
+        public int? Age { get; set; }
+        public Uri Link { get; set; }
+        public List<int> Values { get; set; }
+        public string Kind { get; set; } = "set";
+    }
+}