JSON object/array syntax in <example> XML tags not working

[stevenmccormack]

I am not able to use the null example tags in XML documentation. as decribed in #1768 (comment)
To ensure the problem is not produced by any special configuration in my project I created a new .NET 5 solution based on the Web API template:

SwaggerTest.csproj:

<Project Sdk="Microsoft.NET.Sdk.Web">

    <PropertyGroup>
        <TargetFramework>net5.0</TargetFramework>
    </PropertyGroup>

    <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
      <DocumentationFile>bin\Debug\net5.0\SwaggerTest.xml</DocumentationFile>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Swashbuckle.AspNetCore" Version="6.1.1" />
    </ItemGroup>

</Project>

Startup.cs:

using System;
using System.IO;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;


namespace SwaggerTest {
    public class Startup {
        public Startup(IConfiguration configuration) {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services) {
            services.AddControllers();
            services.AddSwaggerGen(c => { 
                c.SwaggerDoc("v1", new OpenApiInfo {Title = "SwaggerTest", Version = "v1"});
                var filePath = Path.Combine(System.AppContext.BaseDirectory, "SwaggerTest.xml");
                c.IncludeXmlComments(filePath);
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {
            if (env.IsDevelopment()) {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "SwaggerTest v1"));
            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
        }
    }
}

WeatherForecast.cs

using System;

namespace SwaggerTest {
    public class WeatherForecast {
        public DateTime Date { get; set; }

        public int TemperatureC { get; set; }

        public int TemperatureF => 32 + (int) (TemperatureC / 0.5556);

        /// <summary>
        /// This is a test for a string
        /// </summary>
        /// <example>"Hello World!"</example>
        public string Summary { get; set; }

        /// <summary>
        /// This is a test for a string
        /// </summary>
        /// <example>Hello World</example>
        public string UnquotedExampleString { get; set; }

        /// <summary>
        /// This is a test for a string
        /// </summary>
        /// <example>null</example>
        public string NullExampleString { get; set; }

        
        /// <summary>
        /// This is a nullable int
        /// </summary>
        /// <example>null</example>
        public int? SampleIntValue { get; set; }
    }
}

The resulting Sagger Documentation does not pickup the null example:

[wu-yafeng]

Create a ExamplesSchemaFilter.cs in your project:

public class ExamplesSchemaFilter : ISchemaFilter
    {
        private readonly XPathNavigator _xmlNavigator;

        public ExamplesSchemaFilter(XPathDocument xmlDoc)
        {
            _xmlNavigator = xmlDoc.CreateNavigator();
        }
        public void Apply(OpenApiSchema schema, SchemaFilterContext context)
        {
            if (context.MemberInfo != null)
            {
                var fieldOrPropertyMemberName = XmlCommentsNodeNameHelper.GetMemberNameForFieldOrProperty(context.MemberInfo);
                var fieldOrPropertyNode = _xmlNavigator.SelectSingleNode($"/doc/members/member[@name='{fieldOrPropertyMemberName}']");

                if (fieldOrPropertyNode == null) return;

                var exampleNode = fieldOrPropertyNode.SelectSingleNode("example");
                if (exampleNode != null
                    && schema.ResolveType(context.SchemaRepository) == "string")
                {
                    schema.Example = OpenApiAnyFactory.CreateFromJson(exampleNode.InnerXml) ?? new OpenApiNull();
                }
            }
        }
    }

configure the filter in startup ConfigureServices:

 services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "WebApi", Version = "v1" });
                Directory.GetFiles(Environment.ContentRootPath, "*.xml", SearchOption.AllDirectories)
                    .ToList().ForEach(file =>
                    {
                        c.IncludeXmlComments(file);
                        c.SchemaFilter<ExamplesSchemaFilter>(new XPathDocument(file));
                    });
            });

[domaindrivendev]

Fixed by #2151. Released with v6.1.5.