.

README.md

@@ -30,5 +30,17 @@ app.UseExceptionHandler();
 * https://medium.com/@niteshsinghal85/multiple-request-response-examples-for-swagger-ui-in-asp-net-core-864c0bdc6619
 
 ## Request Body에서 null을 명시할 경우 무시할 수 없음
-* JsonIgnoreCondition은 현재 null 쓰기무시만 있고 null 읽기무시는 없음
-* https://github.com/dotnet/runtime/issues/66490#issuecomment-1142804662
+* `JsonIgnoreCondition.WhenReadingNull`이 추가될 예정도 없음
+* https://stackoverflow.com/questions/77516935/ignore-json-null-value-in-system-text-json-deserialize
+
+```csharp
+builder.Services.ConfigureHttpJsonOptions(options => {
+    options.SerializerOptions.WriteIndented = true;
+    options.SerializerOptions.IncludeFields = true;
+    options.SerializerOptions.PreferredObjectCreationHandling = JsonObjectCreationHandling.Populate;
+    options.SerializerOptions.TypeInfoResolver = new DefaultJsonTypeInfoResolver
+    {
+        Modifiers = { InterceptNullSetter }
+    };
+});
+```

src/WebApplicationMinimalApi8/Dto/MessageDto.cs

@@ -6,23 +6,31 @@ namespace WebApplicationMinimalApi8.Dto;
 public record MessageDto
 {
 
-    public string Body { get; init; } = "안녕하신지";
+    public string NullString { get; init; } = "기본값";
+    public IEnumerable<string> NullStrings { get; init; } = [];
 
 }
 
 public class MessageDtoValidator : AbstractValidator<MessageDto>
 {
     public MessageDtoValidator()
     {
-        RuleFor(x => x.Body).NotEmpty().NotNull();
+        RuleFor(x => x.NullString).NotEmpty();
     }
 }
 
+#pragma warning disable CS8625
+
 public class MessageDtoExmaple : IMultipleExamplesProvider<MessageDto>
 {
     public IEnumerable<SwaggerExample<MessageDto>> GetExamples()
     {
-        yield return SwaggerExample.Create("빈값", new MessageDto { Body = "" });
-        yield return SwaggerExample.Create("null", new MessageDto { Body = null });
+        yield return SwaggerExample.Create("null", new MessageDto
+        {
+            NullString = null,
+            NullStrings = null
+        });
+        yield return SwaggerExample.Create("notnull", new MessageDto { NullString = "값", NullStrings = ["값"] });
+        yield return SwaggerExample.Create("error", new MessageDto { NullString = "" });
     }
 }

src/WebApplicationMinimalApi8/Program.cs

@@ -1,10 +1,13 @@
 using System.Reflection.Metadata.Ecma335;
+using System.Text.Json.Serialization.Metadata;
+using System.Text.Json.Serialization;
 using FluentValidation;
 using Microsoft.OpenApi.Models;
 using Swashbuckle.AspNetCore.Filters;
 using WebApplicationMinimalApi8.Dto;
 using WebApplicationMinimalApi8.EndpointFilters;
 using WebApplicationMinimalApi8.ExceptionHandlers;
+using System.Linq;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -16,6 +19,15 @@
 builder.Services.AddSwaggerExamplesFromAssemblyOf<Program>();
 builder.Services.AddValidatorsFromAssemblyContaining<Program>();
 builder.AddFluentValidationEndpointFilter();
+builder.Services.ConfigureHttpJsonOptions(options => {
+    options.SerializerOptions.WriteIndented = true;
+    options.SerializerOptions.IncludeFields = true;
+    options.SerializerOptions.PreferredObjectCreationHandling = JsonObjectCreationHandling.Populate;
+    options.SerializerOptions.TypeInfoResolver = new DefaultJsonTypeInfoResolver
+    {
+        Modifiers = { InterceptNullSetter }
+    };
+});
 
 if (builder.Environment.IsEnvironment("Best"))
 {
@@ -49,3 +61,19 @@
 
 app.Run();
 
+static void InterceptNullSetter(JsonTypeInfo typeInfo)
+{
+    foreach (var (propertyInfo, setProperty) in from propertyInfo in typeInfo.Properties
+                                                let setProperty = propertyInfo.Set
+                                                where setProperty is not null
+                                                select (propertyInfo, setProperty))
+    {
+        propertyInfo.Set = (obj, value) =>
+        {
+            if (value != null)
+            {
+                setProperty(obj, value);
+            }
+        };
+    }
+}