Get default value from constructor when type is a record. (#2428)

Co-authored-by: Michael Staib <michael@chillicream.com>

src/HotChocolate/Core/src/Types/Types/Descriptors/Conventions/DefaultTypeInspector.cs

@@ -27,6 +27,7 @@ public class DefaultTypeInspector
 
         private readonly Dictionary<MemberInfo, ExtendedMethodInfo> _methods =
             new Dictionary<MemberInfo, ExtendedMethodInfo>();
+
         private readonly Dictionary<Type, bool> _records =
             new Dictionary<Type, bool>();
 
@@ -309,6 +310,11 @@ public virtual bool TryGetDefaultValue(PropertyInfo property, out object? defaul
                 return true;
             }
 
+            if (TryGetDefaultValueFromConstructor(property, out defaultValue))
+            {
+                return true;
+            }
+
             defaultValue = null;
             return false;
         }
@@ -566,9 +572,9 @@ private static bool HasConfiguration(ICustomAttributeProvider element)
 
         private static bool IsIgnored(MemberInfo member)
         {
-            if (IsCloneMember(member) || 
-                IsToString(member) || 
-                IsGetHashCode(member) || 
+            if (IsCloneMember(member) ||
+                IsToString(member) ||
+                IsGetHashCode(member) ||
                 IsEquals(member))
             {
                 return true;
@@ -597,6 +603,7 @@ private bool IsRecord(Type type)
                 isRecord = IsRecord(type.GetMembers());
                 _records[type] = isRecord;
             }
+
             return isRecord;
         }
 
@@ -609,6 +616,7 @@ private static bool IsRecord(IReadOnlyList<MemberInfo> members)
                     return true;
                 }
             }
+
             return false;
         }
 
@@ -633,7 +641,8 @@ private static bool IsRecord(IReadOnlyList<MemberInfo> members)
         }
 
         private IEnumerable<T> GetCustomAttributesFromRecord<T>(
-            PropertyInfo property, bool inherit)
+            PropertyInfo property,
+            bool inherit)
             where T : Attribute
         {
             Type recordType = property.DeclaringType!;
@@ -661,7 +670,8 @@ private static bool IsRecord(IReadOnlyList<MemberInfo> members)
         }
 
         private T? GetCustomAttributeFromRecord<T>(
-            PropertyInfo property, bool inherit)
+            PropertyInfo property,
+            bool inherit)
             where T : Attribute
         {
             Type recordType = property.DeclaringType!;
@@ -687,7 +697,8 @@ private static bool IsRecord(IReadOnlyList<MemberInfo> members)
         }
 
         private static bool IsDefinedOnRecord<T>(
-            PropertyInfo property, bool inherit)
+            PropertyInfo property,
+            bool inherit)
             where T : Attribute
         {
             Type recordType = property.DeclaringType!;
@@ -711,5 +722,29 @@ private static bool IsRecord(IReadOnlyList<MemberInfo> members)
 
             return false;
         }
+
+        private bool TryGetDefaultValueFromConstructor(
+            PropertyInfo property,
+            out object? defaultValue)
+        {
+            defaultValue = null;
+            if (IsRecord(property.DeclaringType!))
+            {
+                ConstructorInfo[] constructors = property.DeclaringType!.GetConstructors();
+
+                if (constructors.Length == 1)
+                {
+                    foreach (ParameterInfo parameter in constructors[0].GetParameters())
+                    {
+                        if (parameter.Name.EqualsOrdinal(property.Name))
+                        {
+                            return TryGetDefaultValue(parameter, out defaultValue);
+                        }
+                    }
+                }
+            }
+
+            return false;
+        }
     }
-}
+}

src/HotChocolate/Core/test/Types.Records.Tests/RecordsTests.cs

@@ -1,49 +1,71 @@
-using System;
-using Microsoft.Extensions.DependencyInjection;
-using HotChocolate.Types.Relay;
-using static HotChocolate.Tests.TestHelper;
-using System.Threading.Tasks;
-using HotChocolate.Tests;
-using Snapshooter.Xunit;
-using Xunit;
-using HotChocolate.Execution;
-
-namespace HotChocolate.Types
-{
-    public class RecordsTests
-    {
-        [Fact]
-        public async Task Records_Clone_Member_Is_Removed()
-        {
-            Snapshot.FullName();
-
-            await new ServiceCollection()
-                .AddGraphQL()
-                .AddQueryType<Query>()
-                .Services
-                .BuildServiceProvider()
-                .GetSchemaAsync()
-                .MatchSnapshotAsync();
-        }
-
-        [Fact]
-        public async Task Relay_Id_Middleware_Is_Correctly_Applied()
-        {
-            Snapshot.FullName();
-
-            await ExpectValid
-            (
-                @"{ person { id name } }",
-                b => b.AddQueryType<Query>()
-            )
-            .MatchSnapshotAsync(); ;
-        }
-
-        public class Query
-        {
-            public Person GetPerson() => new Person(1, "Michael");
-        }
-
-        public record Person([ID] int Id, string Name);
-    }
-}
+using System;
+using Microsoft.Extensions.DependencyInjection;
+using HotChocolate.Types.Relay;
+using static HotChocolate.Tests.TestHelper;
+using System.Threading.Tasks;
+using HotChocolate.Tests;
+using Snapshooter.Xunit;
+using Xunit;
+using HotChocolate.Execution;
+
+namespace HotChocolate.Types
+{
+    public class RecordsTests
+    {
+        [Fact]
+        public async Task Records_Clone_Member_Is_Removed()
+        {
+            Snapshot.FullName();
+
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<Query>()
+                .Services
+                .BuildServiceProvider()
+                .GetSchemaAsync()
+                .MatchSnapshotAsync();
+        }
+
+        [Fact]
+        public async Task Records_Default_Value_Is_Taken_From_Ctor()
+        {
+            Snapshot.FullName();
+
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<Query2>()
+                .Services
+                .BuildServiceProvider()
+                .GetSchemaAsync()
+                .MatchSnapshotAsync();
+        }
+
+        [Fact]
+        public async Task Relay_Id_Middleware_Is_Correctly_Applied()
+        {
+            Snapshot.FullName();
+
+            await ExpectValid
+            (
+                @"{ person { id name } }",
+                b => b.AddQueryType<Query>()
+            )
+            .MatchSnapshotAsync();
+        }
+
+        public class Query
+        {
+            public Person GetPerson() => new Person(1, "Michael");
+        }
+
+        public record Person([ID] int Id, string Name);
+
+        public class Query2
+        {
+            public DefaultValueTest GetPerson(DefaultValueTest? defaultValueTest) =>
+                new DefaultValueTest(1, "Test");
+        }
+
+        public record DefaultValueTest([ID] int Id, string Name = "ShouldBeDefaultValue");
+    }
+}

src/HotChocolate/Core/test/Types.Records.Tests/__snapshots__/RecordsTests.Records_Default_Value_Is_Taken_From_Ctor.snap

@@ -0,0 +1,23 @@
+schema {
+  query: Query2
+}
+
+type DefaultValueTest {
+  id: ID!
+  name: String!
+}
+
+type Query2 {
+  person(defaultValueTest: DefaultValueTestInput): DefaultValueTest!
+}
+
+input DefaultValueTestInput {
+  id: ID!
+  name: String! = "ShouldBeDefaultValue"
+}
+
+"The `ID` scalar type represents a unique identifier, often used to refetch an object or as key for a cache. The ID type appears in a JSON response as a String; however, it is not intended to be human-readable. When expected as an input type, any string (such as `\"4\"`) or integer (such as `4`) input value will be accepted as an ID."
+scalar ID
+
+"The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text."
+scalar String