Fix that XML comment examples do not show up if the type is string and the example contains quotation marks

src/Swashbuckle.AspNetCore.SwaggerGen/XmlComments/XmlCommentsExampleHelper.cs

@@ -0,0 +1,27 @@
+using System.Text.Json;
+using Microsoft.OpenApi.Any;
+using Microsoft.OpenApi.Models;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen
+{
+    internal static class XmlCommentsExampleHelper
+    {
+        public static IOpenApiAny Create(
+            SchemaRepository schemaRepository,
+            OpenApiSchema schema,
+            string exampleString)
+        {
+            var isStringType =
+                (schema?.ResolveType(schemaRepository) == "string") &&
+                !string.Equals(exampleString, "null");
+
+            var exampleAsJson = isStringType
+                    ? JsonSerializer.Serialize(exampleString)
+                    : exampleString;
+
+            var example = OpenApiAnyFactory.CreateFromJson(exampleAsJson);
+
+            return example;
+        }
+    }
+}

src/Swashbuckle.AspNetCore.SwaggerGen/XmlComments/XmlCommentsParameterFilter.cs

@@ -42,11 +42,7 @@ private void ApplyPropertyTags(OpenApiParameter parameter, ParameterFilterContex
             var exampleNode = propertyNode.SelectSingleNode("example");
             if (exampleNode == null) return;
 
-            var exampleAsJson = (parameter.Schema?.ResolveType(context.SchemaRepository) == "string")
-                ? $"\"{exampleNode.ToString()}\""
-                : exampleNode.ToString();
-
-            parameter.Example = OpenApiAnyFactory.CreateFromJson(exampleAsJson);
+            parameter.Example = XmlCommentsExampleHelper.Create(context.SchemaRepository, parameter.Schema, exampleNode.ToString());
         }
 
         private void ApplyParamTags(OpenApiParameter parameter, ParameterFilterContext context)
@@ -71,11 +67,7 @@ private void ApplyParamTags(OpenApiParameter parameter, ParameterFilterContext c
                 var example = paramNode.GetAttribute("example", "");
                 if (string.IsNullOrEmpty(example)) return;
 
-                var exampleAsJson = (parameter.Schema?.ResolveType(context.SchemaRepository) == "string")
-                    ? $"\"{example}\""
-                    : example;
-
-                parameter.Example = OpenApiAnyFactory.CreateFromJson(exampleAsJson);
+                parameter.Example = XmlCommentsExampleHelper.Create(context.SchemaRepository, parameter.Schema, example);
             }
         }
     }

src/Swashbuckle.AspNetCore.SwaggerGen/XmlComments/XmlCommentsRequestBodyFilter.cs

@@ -50,11 +50,7 @@ private void ApplyPropertyTags(OpenApiRequestBody requestBody, RequestBodyFilter
 
             foreach (var mediaType in requestBody.Content.Values)
             {
-                var exampleAsJson = (mediaType.Schema?.ResolveType(context.SchemaRepository) == "string")
-                    ? $"\"{exampleNode.ToString()}\""
-                    : exampleNode.ToString();
-
-                mediaType.Example = OpenApiAnyFactory.CreateFromJson(exampleAsJson);
+                mediaType.Example = XmlCommentsExampleHelper.Create(context.SchemaRepository, mediaType.Schema, exampleNode.ToString());
             }
         }
 
@@ -82,11 +78,7 @@ private void ApplyParamTags(OpenApiRequestBody requestBody, RequestBodyFilterCon
 
                 foreach (var mediaType in requestBody.Content.Values)
                 {
-                    var exampleAsJson = (mediaType.Schema?.ResolveType(context.SchemaRepository) == "string")
-                        ? $"\"{example}\""
-                        : example;
-
-                    mediaType.Example = OpenApiAnyFactory.CreateFromJson(exampleAsJson);
+                    mediaType.Example = XmlCommentsExampleHelper.Create(context.SchemaRepository, mediaType.Schema, example);
                 }
             }
         }

src/Swashbuckle.AspNetCore.SwaggerGen/XmlComments/XmlCommentsSchemaFilter.cs

@@ -69,11 +69,7 @@ private static void TrySetExample(OpenApiSchema schema, SchemaFilterContext cont
             if (example == null)
                 return;
 
-            var exampleAsJson = (schema.ResolveType(context.SchemaRepository) == "string") && !example.Equals("null")
-                ? $"\"{example}\""
-                : example;
-
-            schema.Example = OpenApiAnyFactory.CreateFromJson(exampleAsJson);
+            schema.Example = XmlCommentsExampleHelper.Create(context.SchemaRepository, schema, example);
         }
     }
 }

test/Swashbuckle.AspNetCore.SwaggerGen.Test/Fixtures/FakeConstructedControllerWithXmlComments.cs

@@ -17,8 +17,8 @@ public class GenericControllerWithXmlComments<T>
         public void ActionWithSummaryAndResponseTags(T param)
         { }
 
-        /// <param name="param1" example="Example for param1">Description for param1</param>
-        /// <param name="param2" example="Example for param2">Description for param2</param>
+        /// <param name="param1" example="Example for &quot;param1&quot;">Description for param1</param>
+        /// <param name="param2" example="Example for &quot;param2&quot;">Description for param2</param>
         public void ActionWithParamTags(T param1, T param2)
         { }
     }

test/Swashbuckle.AspNetCore.SwaggerGen.Test/Fixtures/FakeControllerWithXmlComments.cs

@@ -18,7 +18,7 @@ public class FakeControllerWithXmlComments
         public void ActionWithSummaryAndRemarksTags()
         { }
 
-        /// <param name="param1" example="Example for param1">Description for param1</param>
+        /// <param name="param1" example="Example for &quot;param1&quot;">Description for param1</param>
         /// <param name="param2" example="http://test.com/?param1=1&amp;param2=2">Description for param2</param>
         public void ActionWithParamTags(string param1, string param2)
         { }

test/Swashbuckle.AspNetCore.SwaggerGen.Test/XmlComments/XmlCommentsExampleHelperTests.cs

@@ -0,0 +1,74 @@
+using Microsoft.OpenApi.Any;
+using Microsoft.OpenApi.Models;
+using Xunit;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.Test
+{
+    public class XmlCommentsExampleHelperTests
+    {
+        private readonly SchemaRepository schemaRepository = new SchemaRepository();
+
+        [Fact]
+        public void Create_BuildsOpenApiArrayJson__When_NotStringTypeAndDataIsArray()
+        {
+            var schema = new OpenApiSchema();
+
+            IOpenApiAny example = XmlCommentsExampleHelper.Create(
+                schemaRepository,
+                schema,
+                "[\"one\",\"two\",\"three\"]");
+
+            Assert.NotNull(example);
+            var actual = Assert.IsType<OpenApiArray>(example);
+            Assert.Equal(3, actual.Count);
+
+            var item1 = Assert.IsType<OpenApiString>(actual[0]);
+            var item2 = Assert.IsType<OpenApiString>(actual[1]);
+            var item3 = Assert.IsType<OpenApiString>(actual[2]);
+            Assert.Equal("one",   item1.Value);
+            Assert.Equal("two",   item2.Value);
+            Assert.Equal("three", item3.Value);
+        }
+
+        [Fact]
+        public void Create_BuildsOpenApiString_When_TypeString()
+        {
+            string exampleString = "example string with special characters\"<>\r\n\"";
+            OpenApiSchema schema = new OpenApiSchema { Type = "string" };
+            schemaRepository.AddDefinition("test", schema);
+
+            IOpenApiAny example = XmlCommentsExampleHelper.Create(
+                schemaRepository, schema, exampleString);
+
+            Assert.NotNull(example);
+            var actual = Assert.IsType<OpenApiString>(example);
+            Assert.Equal(actual.Value, exampleString);
+        }
+
+        [Fact]
+        public void Create_ReturnsNull_When_TypeString_and_ValueNull()
+        {
+            OpenApiSchema schema = new OpenApiSchema { Type = "string" };
+            schemaRepository.AddDefinition("test", schema);
+
+            IOpenApiAny example = XmlCommentsExampleHelper.Create(
+                schemaRepository, schema, "null");
+
+            Assert.NotNull(example);
+            var actual = Assert.IsType<OpenApiNull>(example);
+            Assert.Equal(AnyType.Null, actual.AnyType);
+        }
+
+        [Fact]
+        public void Create_AllowsSchemaToBeNull()
+        {
+            OpenApiSchema schema = null;
+
+            IOpenApiAny example = XmlCommentsExampleHelper.Create(schemaRepository, schema, "[]");
+
+            Assert.NotNull(example);
+            var actual = Assert.IsType<OpenApiArray>(example);
+            Assert.Empty(actual);
+        }
+    }
+}

test/Swashbuckle.AspNetCore.SwaggerGen.Test/XmlComments/XmlCommentsParameterFilterTests.cs

@@ -23,7 +23,7 @@ public void Apply_SetsDescriptionAndExample_FromActionParamTag()
 
             Assert.Equal("Description for param1", parameter.Description);
             Assert.NotNull(parameter.Example);
-            Assert.Equal("\"Example for param1\"", parameter.Example.ToJson());
+            Assert.Equal("\"Example for \\\"param1\\\"\"", parameter.Example.ToJson());
         }
 
         [Fact]
@@ -57,7 +57,7 @@ public void Apply_SetsDescriptionAndExample_FromUnderlyingGenericTypeActionParam
 
             Assert.Equal("Description for param1", parameter.Description);
             Assert.NotNull(parameter.Example);
-            Assert.Equal("\"Example for param1\"", parameter.Example.ToJson());
+            Assert.Equal("\"Example for \\\"param1\\\"\"", parameter.Example.ToJson());
         }
 
         [Fact]

test/Swashbuckle.AspNetCore.SwaggerGen.Test/XmlComments/XmlCommentsRequestBodyFilterTests.cs

@@ -34,7 +34,7 @@ public void Apply_SetsDescriptionAndExample_FromActionParamTag()
 
             Assert.Equal("Description for param1", requestBody.Description);
             Assert.NotNull(requestBody.Content["application/json"].Example);
-            Assert.Equal("\"Example for param1\"", requestBody.Content["application/json"].Example.ToJson());
+            Assert.Equal("\"Example for \\\"param1\\\"\"", requestBody.Content["application/json"].Example.ToJson());
         }
 
         [Fact]
@@ -60,7 +60,7 @@ public void Apply_SetsDescriptionAndExample_FromUnderlyingGenericTypeActionParam
 
             Assert.Equal("Description for param1", requestBody.Description);
             Assert.NotNull(requestBody.Content["application/json"].Example);
-            Assert.Equal("\"Example for param1\"", requestBody.Content["application/json"].Example.ToJson());
+            Assert.Equal("\"Example for \\\"param1\\\"\"", requestBody.Content["application/json"].Example.ToJson());
         }
 
         [Fact]