Fix DateFormatConverter for System.Text.Json (#1490)

src/NJsonSchema.CodeGeneration.CSharp.Tests/GeneralGeneratorTests.cs

@@ -1461,6 +1461,39 @@ public async Task When_definition_contains_date_converter_should_be_added_for_da
             AssertCompile(code);
         }
 
+        [Fact]
+        public async Task When_definition_contains_date_and_use_system_text_json_then_converter_should_be_added_for_datetime()
+        {
+            //// Arrange
+            var json =
+@"{
+	""type"": ""object"",
+	""properties"": {
+		""a"": {
+    		""type"": ""string"",
+            ""format"": ""date""
+        }
+	}
+}";
+            var schema = await JsonSchema.FromJsonAsync(json);
+
+            //// Act
+            var generator = new CSharpGenerator(schema, new CSharpGeneratorSettings
+            {
+                ClassStyle = CSharpClassStyle.Poco,
+                SchemaType = SchemaType.Swagger2,
+                DateType = "System.DateTime",
+                JsonLibrary = CSharpJsonLibrary.SystemTextJson
+            });
+            var code = generator.GenerateFile("MyClass");
+
+            //// Assert
+            Assert.Contains(@"class DateFormatConverter", code);
+            Assert.Contains(@"[System.Text.Json.Serialization.JsonConverter(typeof(DateFormatConverter))]", code);
+
+            AssertCompile(code);
+        }
+
         [Fact]
         public async Task When_no_typeNameHint_is_available_then_title_is_used_as_class_name()
         {
@@ -1605,6 +1638,39 @@ public async Task When_definition_contains_date_converter_should_be_added_for_da
             AssertCompile(code);
         }
 
+        [Fact]
+        public async Task When_definition_contains_date_and_use_system_text_json_then_converter_should_be_added_for_datetimeoffset()
+        {
+            //// Arrange
+            var json =
+@"{
+	""type"": ""object"",
+	""properties"": {
+		""a"": {
+    		""type"": ""string"",
+            ""format"": ""date""
+        }
+	}
+}";
+            var schema = await JsonSchema.FromJsonAsync(json);
+
+            //// Act
+            var generator = new CSharpGenerator(schema, new CSharpGeneratorSettings
+            {
+                ClassStyle = CSharpClassStyle.Poco,
+                SchemaType = SchemaType.Swagger2,
+                DateType = "System.DateTimeOffset",
+                JsonLibrary = CSharpJsonLibrary.SystemTextJson
+            });
+            var code = generator.GenerateFile("MyClass");
+
+            //// Assert
+            Assert.Contains(@"class DateFormatConverter", code);
+            Assert.Contains(@"[System.Text.Json.Serialization.JsonConverter(typeof(DateFormatConverter))]", code);
+
+            AssertCompile(code);
+        }
+
         [Fact]
         public async Task When_definition_contains_datetime_converter_should_not_be_added()
         {
@@ -1637,6 +1703,39 @@ public async Task When_definition_contains_datetime_converter_should_not_be_adde
             AssertCompile(code);
         }
 
+        [Fact]
+        public async Task When_definition_contains_datetime_and_use_system_text_json_then_converter_should_not_be_added()
+        {
+            //// Arrange
+            var json =
+                @"{
+	""type"": ""object"",
+	""properties"": {
+		""a"": {
+    		""type"": ""string"",
+            ""format"": ""date-time""
+        }
+	}
+}";
+            var schema = await JsonSchema.FromJsonAsync(json);
+
+            //// Act
+            var generator = new CSharpGenerator(schema, new CSharpGeneratorSettings
+            {
+                ClassStyle = CSharpClassStyle.Poco,
+                SchemaType = SchemaType.Swagger2,
+                DateType = "System.DateTime",
+                JsonLibrary = CSharpJsonLibrary.SystemTextJson
+            });
+            var code = generator.GenerateFile("MyClass");
+
+            //// Assert
+            Assert.DoesNotContain(@"class DateFormatConverter", code);
+            Assert.DoesNotContain(@"[System.Text.Json.Serialization.JsonConverter(typeof(DateFormatConverter))]", code);
+
+            AssertCompile(code);
+        }
+
         [Fact]
         public async Task When_record_no_setter_in_class_and_constructor_provided()
         {

src/NJsonSchema.CodeGeneration.CSharp/Models/DateFormatConverterTemplateModel.cs

@@ -20,8 +20,11 @@ public DateFormatConverterTemplateModel(CSharpGeneratorSettings settings)
         {
             _settings = settings;
         }
-
+        
         /// <summary>Gets or sets a value indicating whether to generate the DateFormatConverter class.</summary>
         public bool GenerateDateFormatConverterClass => _settings.ExcludedTypeNames?.Contains("DateFormatConverter") != true;
+
+        /// <summary>Gets a value indicating whether to use System.Text.Json</summary>
+        public bool UseSystemTextJson => _settings.JsonLibrary == CSharpJsonLibrary.SystemTextJson;
     }
 }

src/NJsonSchema.CodeGeneration.CSharp/Templates/DateFormatConverter.liquid

@@ -1,13 +1,19 @@
 [System.CodeDom.Compiler.GeneratedCode("NJsonSchema", "{{ ToolchainVersion }}")]
 {%- if UseSystemTextJson -%}
-internal class DateFormatConverter : JsonConverter<DateTime>
+internal class DateFormatConverter : System.Text.Json.Serialization.JsonConverter<System.DateTime>
 {
     public override System.DateTime Read(ref System.Text.Json.Utf8JsonReader reader, System.Type typeToConvert, System.Text.Json.JsonSerializerOptions options)
     {
-        return DateTime.Parse(reader.GetString());
+        var dateTime = reader.GetString();
+        if (dateTime == null)
+        {
+            throw new JsonException("Unexpected JsonTokenType.Null");
+        }
+
+        return System.DateTime.Parse(dateTime);
     }
 
-    public override void Write(System.Text.Json.Utf8JsonReader writer, System.DateTime value, System.Text.Json.JsonSerializerOptions options)
+    public override void Write(System.Text.Json.Utf8JsonWriter writer, System.DateTime value, System.Text.Json.JsonSerializerOptions options)
     {
         writer.WriteStringValue(value.ToString("yyyy-MM-dd"));
     }