如何使用 Swashbuckle 在 Swagger API 文档/OpenAPI 规范中包含子类？

Question

我在 c# 中有一个 Asp.Net web API 5.2 项目并使用 Swashbuckle 生成文档。

我有一个包含继承的模型，例如从 Animal 抽象 class 获得 Animal 属性以及派生自它的 Dog 和 Cat class。

Swashbuckle 仅显示 Animal class 的架构，所以我尝试使用 ISchemaFilter（他们也建议这样做）但我无法使其工作，而且我找不到合适的示例。

有人可以帮忙吗？

Answer 1

似乎 Swashbuckle 没有正确实现多态性，我理解作者关于 subclasses 作为参数的观点（如果一个动作期望一个 Animal class 并且行为不同，如果你用狗对象或猫对象调用它，那么你应该有 2 个不同的动作......）但是作为 return 类型我相信它是正确的 return 动物并且对象可以是狗或猫类型。

因此，为了描述我的 API 并根据正确的准则生成适当的 JSON 模式（请注意我描述鉴别器的方式，如果您有自己的鉴别器，则可能需要特别更改那部分），我按如下方式使用文档和模式过滤器：

SwaggerDocsConfig configuration;
.....
configuration.DocumentFilter<PolymorphismDocumentFilter<YourBaseClass>>();
configuration.SchemaFilter<PolymorphismSchemaFilter<YourBaseClass>>();
.....

public class PolymorphismSchemaFilter<T> : ISchemaFilter
{
    private readonly Lazy<HashSet<Type>> derivedTypes = new Lazy<HashSet<Type>>(Init);

    private static HashSet<Type> Init()
    {
        var abstractType = typeof(T);
        var dTypes = abstractType.Assembly
                                 .GetTypes()
                                 .Where(x => abstractType != x && abstractType.IsAssignableFrom(x));

        var result = new HashSet<Type>();

        foreach (var item in dTypes)
            result.Add(item);

        return result;
    }

    public void Apply(Schema schema, SchemaRegistry schemaRegistry, Type type)
    {
        if (!derivedTypes.Value.Contains(type)) return;

        var clonedSchema = new Schema
                                {
                                    properties = schema.properties,
                                    type = schema.type,
                                    required = schema.required
                                };

        //schemaRegistry.Definitions[typeof(T).Name]; does not work correctly in SwashBuckle
        var parentSchema = new Schema { @ref = "#/definitions/" + typeof(T).Name };   

        schema.allOf = new List<Schema> { parentSchema, clonedSchema };

        //reset properties for they are included in allOf, should be null but code does not handle it
        schema.properties = new Dictionary<string, Schema>();
    }
}

public class PolymorphismDocumentFilter<T> : IDocumentFilter
{
    public void Apply(SwaggerDocument swaggerDoc, SchemaRegistry schemaRegistry, System.Web.Http.Description.IApiExplorer apiExplorer)
    {
        RegisterSubClasses(schemaRegistry, typeof(T));
    }

    private static void RegisterSubClasses(SchemaRegistry schemaRegistry, Type abstractType)
    {
        const string discriminatorName = "discriminator";

        var parentSchema = schemaRegistry.Definitions[SchemaIdProvider.GetSchemaId(abstractType)];

        //set up a discriminator property (it must be required)
        parentSchema.discriminator = discriminatorName;
        parentSchema.required = new List<string> { discriminatorName };

        if (!parentSchema.properties.ContainsKey(discriminatorName))
            parentSchema.properties.Add(discriminatorName, new Schema { type = "string" });

        //register all subclasses
        var derivedTypes = abstractType.Assembly
                                       .GetTypes()
                                       .Where(x => abstractType != x && abstractType.IsAssignableFrom(x));

        foreach (var item in derivedTypes)
            schemaRegistry.GetOrRegister(item);
    }
}

在“支持多态性的模型”部分中指定了here之前代码实现的内容。它基本上产生如下内容：

{
  "definitions": {
    "Pet": {
      "type": "object",
      "discriminator": "petType",
      "properties": {
        "name": {
          "type": "string"
        },
        "petType": {
          "type": "string"
        }
      },
      "required": [
        "name",
        "petType"
      ]
    },
    "Cat": {
      "description": "A representation of a cat",
      "allOf": [
        {
          "$ref": "#/definitions/Pet"
        },
        {
          "type": "object",
          "properties": {
            "huntingSkill": {
              "type": "string",
              "description": "The measured skill for hunting",
              "default": "lazy",
              "enum": [
                "clueless",
                "lazy",
                "adventurous",
                "aggressive"
              ]
            }
          },
          "required": [
            "huntingSkill"
          ]
        }
      ]
    },
    "Dog": {
      "description": "A representation of a dog",
      "allOf": [
        {
          "$ref": "#/definitions/Pet"
        },
        {
          "type": "object",
          "properties": {
            "packSize": {
              "type": "integer",
              "format": "int32",
              "description": "the size of the pack the dog is from",
              "default": 0,
              "minimum": 0
            }
          },
          "required": [
            "packSize"
          ]
        }
      ]
    }
  }
}

Answer 2

要继续 Paulo 的精彩回答，如果您使用的是 Swagger 2.0，则需要修改类，如下所示：

public class PolymorphismSchemaFilter<T> : ISchemaFilter
{
    private readonly Lazy<HashSet<Type>> derivedTypes = new Lazy<HashSet<Type>>(Init);

    private static HashSet<Type> Init()
    {
        var abstractType = typeof(T);
        var dTypes = abstractType.Assembly
                                 .GetTypes()
                                 .Where(x => abstractType != x && abstractType.IsAssignableFrom(x));

        var result = new HashSet<Type>();

        foreach (var item in dTypes)
            result.Add(item);

        return result;
    }

    public void Apply(Schema model, SchemaFilterContext context)
    {
        if (!derivedTypes.Value.Contains(context.SystemType)) return;

        var clonedSchema = new Schema
        {
            Properties = model.Properties,
            Type = model.Type,
            Required = model.Required
        };

        //schemaRegistry.Definitions[typeof(T).Name]; does not work correctly in SwashBuckle
        var parentSchema = new Schema { Ref = "#/definitions/" + typeof(T).Name };

        model.AllOf = new List<Schema> { parentSchema, clonedSchema };

        //reset properties for they are included in allOf, should be null but code does not handle it
        model.Properties = new Dictionary<string, Schema>();
    }
}

public class PolymorphismDocumentFilter<T> : IDocumentFilter
{
    private static void RegisterSubClasses(ISchemaRegistry schemaRegistry, Type abstractType)
    {
        const string discriminatorName = "discriminator";

        var parentSchema = schemaRegistry.Definitions[abstractType.Name];

        //set up a discriminator property (it must be required)
        parentSchema.Discriminator = discriminatorName;
        parentSchema.Required = new List<string> { discriminatorName };

        if (!parentSchema.Properties.ContainsKey(discriminatorName))
            parentSchema.Properties.Add(discriminatorName, new Schema { Type = "string" });

        //register all subclasses
        var derivedTypes = abstractType.Assembly
                                       .GetTypes()
                                       .Where(x => abstractType != x && abstractType.IsAssignableFrom(x));

        foreach (var item in derivedTypes)
            schemaRegistry.GetOrRegister(item);
    }

    public void Apply(SwaggerDocument swaggerDoc, DocumentFilterContext context)
    {
        RegisterSubClasses(context.SchemaRegistry, typeof(T));
    }
}

Answer 3

我想跟进 Craig 的回答。

如果您使用 NSwag 从使用 Swashbuckle 生成的 Swagger API 文档（3.x 在撰写本文时）使用 and further enhanced in 中解释的方法生成 TypeScript 定义，您可能会面临以下问题：

生成的 TypeScript 定义将具有重复的属性，即使生成的 classes 将扩展基础 classes。考虑以下 C# classes:

public abstract class BaseClass
{
    public string BaseProperty { get; set; }
}

public class ChildClass : BaseClass
{
    public string ChildProperty { get; set; }
}

使用上述答案时，IBaseClass 和 IChildClass 接口的最终 TypeScript 定义如下所示：

export interface IBaseClass {
    baseProperty : string | undefined;
}

export interface IChildClass extends IBaseClass {
    baseProperty : string | undefined;
    childProperty: string | undefined;
}

如您所见，baseProperty 在基础和子 class 中的定义都不正确。为了解决这个问题，我们可以修改 PolymorphismSchemaFilter<T> class 的 Apply 方法以仅将拥有的属性包含到模式中，即从当前类型模式中排除继承的属性。这是一个例子：

public void Apply(Schema model, SchemaFilterContext context)
{
    ...

    // Prepare a dictionary of inherited properties
    var inheritedProperties = context.SystemType.GetProperties()
        .Where(x => x.DeclaringType != context.SystemType)
        .ToDictionary(x => x.Name, StringComparer.OrdinalIgnoreCase);

    var clonedSchema = new Schema
    {
        // Exclude inherited properties. If not excluded, 
        // they would have appeared twice in nswag-generated typescript definition
        Properties =
            model.Properties.Where(x => !inheritedProperties.ContainsKey(x.Key))
                .ToDictionary(x => x.Key, x => x.Value),
        Type = model.Type,
        Required = model.Required
    };

    ...
}

生成的 TypeScript 定义不会引用任何现有中间抽象 classes 中的属性。考虑以下 C# classes:

public abstract class SuperClass
{
    public string SuperProperty { get; set; }
}

public abstract class IntermediateClass : SuperClass
{
     public string IntermediateProperty { get; set; }
}

public class ChildClass : BaseClass
{
    public string ChildProperty { get; set; }
}

在这种情况下，生成的 TypeScript 定义将如下所示：

export interface ISuperClass {
    superProperty: string | undefined;
}        

export interface IIntermediateClass extends ISuperClass {
    intermediateProperty : string | undefined;
}

export interface IChildClass extends ISuperClass {
    childProperty: string | undefined;
}

注意生成的 IChildClass 接口如何直接扩展 ISuperClass，忽略 IIntermediateClass 接口，有效地使 IChildClass 的任何实例都没有 intermediateProperty 属性.

我们可以使用下面的代码来解决这个问题：

public void Apply(Schema model, SchemaFilterContext context)
{
    ...

    // Use the BaseType name for parentSchema instead of typeof(T), 
    // because we could have more classes in the hierarchy
    var parentSchema = new Schema
    {
        Ref = "#/definitions/" + (context.SystemType.BaseType?.Name ?? typeof(T).Name)
    };

    ...
}

这将确保子 class 正确引用中间 class。

总之，最终的代码应该是这样的：

    public void Apply(Schema model, SchemaFilterContext context)
    {
        if (!derivedTypes.Value.Contains(context.SystemType))
        {
            return;
        }

        // Prepare a dictionary of inherited properties
        var inheritedProperties = context.SystemType.GetProperties()
            .Where(x => x.DeclaringType != context.SystemType)
            .ToDictionary(x => x.Name, StringComparer.OrdinalIgnoreCase);

        var clonedSchema = new Schema
        {
            // Exclude inherited properties. If not excluded, 
            // they would have appeared twice in nswag-generated typescript definition
            Properties =
                model.Properties.Where(x => !inheritedProperties.ContainsKey(x.Key))
                    .ToDictionary(x => x.Key, x => x.Value),
            Type = model.Type,
            Required = model.Required
        };

        // Use the BaseType name for parentSchema instead of typeof(T), 
        // because we could have more abstract classes in the hierarchy
        var parentSchema = new Schema
        {
            Ref = "#/definitions/" + (context.SystemType.BaseType?.Name ?? typeof(T).Name)
        };
        model.AllOf = new List<Schema> { parentSchema, clonedSchema };

        // reset properties for they are included in allOf, should be null but code does not handle it
        model.Properties = new Dictionary<string, Schema>();
    }

Answer 4

我们最近升级到 .NET Core 3.1 和 Swashbuckle.AspNetCore 5.0 API 有所改变。如果有人需要这个过滤器，这里是通过最少的更改获得类似行为的代码：

public class PolymorphismDocumentFilter<T> : IDocumentFilter
{
    public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
    {
        RegisterSubClasses(context.SchemaRepository, context.SchemaGenerator, typeof(T));
    }

    private static void RegisterSubClasses(SchemaRepository schemaRegistry, ISchemaGenerator schemaGenerator, Type abstractType)
    {
        const string discriminatorName = "$type";
        OpenApiSchema parentSchema = null;

        if (schemaRegistry.TryGetIdFor(abstractType, out string parentSchemaId))
            parentSchema = schemaRegistry.Schemas[parentSchemaId];
        else
            parentSchema = schemaRegistry.GetOrAdd(abstractType, parentSchemaId, () => new OpenApiSchema());

        // set up a discriminator property (it must be required)
        parentSchema.Discriminator = new OpenApiDiscriminator() { PropertyName = discriminatorName };
        parentSchema.Required = new HashSet<string> { discriminatorName };

        if (parentSchema.Properties == null)
            parentSchema.Properties = new Dictionary<string, OpenApiSchema>();

        if (!parentSchema.Properties.ContainsKey(discriminatorName))
            parentSchema.Properties.Add(discriminatorName, new OpenApiSchema() { Type = "string", Default = new OpenApiString(abstractType.FullName) });

        // register all subclasses
        var derivedTypes = abstractType.GetTypeInfo().Assembly.GetTypes()
            .Where(x => abstractType != x && abstractType.IsAssignableFrom(x));

        foreach (var item in derivedTypes)
            schemaGenerator.GenerateSchema(item, schemaRegistry);
    }
}

public class PolymorphismSchemaFilter<T> : ISchemaFilter
{
    private readonly Lazy<HashSet<Type>> derivedTypes = new Lazy<HashSet<Type>>(Init);

    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        if (!derivedTypes.Value.Contains(context.Type)) return;

        Type type = context.Type;
        var clonedSchema = new OpenApiSchema
        {
            Properties = schema.Properties,
            Type = schema.Type,
            Required = schema.Required
        };

        // schemaRegistry.Definitions[typeof(T).Name]; does not work correctly in Swashbuckle.AspNetCore
        var parentSchema = new OpenApiSchema
        {
            Reference = new OpenApiReference() { ExternalResource = "#/definitions/" + typeof(T).Name }
        };

        var assemblyName = Assembly.GetAssembly(type).GetName();
        schema.Discriminator = new OpenApiDiscriminator() { PropertyName = "$type" };
        // This is required if you use Microsoft's AutoRest client to generate the JavaScript/TypeScript models
        schema.Extensions.Add("x-ms-discriminator-value", new OpenApiObject() { ["name"] = new OpenApiString($"{type.FullName}, {assemblyName.Name}") });
        schema.AllOf = new List<OpenApiSchema> { parentSchema, clonedSchema };

        // reset properties for they are included in allOf, should be null but code does not handle it
        schema.Properties = new Dictionary<string, OpenApiSchema>();
    }

    private static HashSet<Type> Init()
    {
        var abstractType = typeof(T);
        var dTypes = abstractType.GetTypeInfo().Assembly
            .GetTypes()
            .Where(x => abstractType != x && abstractType.IsAssignableFrom(x));

        var result = new HashSet<Type>();
        foreach (var item in dTypes)
            result.Add(item);
        return result;
    }
}

我没有完全检查结果，但它似乎给出了相同的行为。

另请注意，您需要导入这些命名空间：

using Microsoft.OpenApi.Models;
using Microsoft.OpenApi.Any;
using System.Reflection;
using Swashbuckle.AspNetCore.SwaggerGen;

Answer 5

从 this merge 到 Swashbuckle.AspNetCore，您可以使用以下方法获得对多态模式的基本支持：

services.AddSwaggerGen(c =>
{
    c.GeneratePolymorphicSchemas();
}

您还可以通过注释库中的属性表达您的派生类型：

[SwaggerSubTypes(typeof(SubClass), Discriminator = "value")]

This article 详细介绍了如何使用 Newtonsoft 反序列化派生类型。

Answer 6

从 5.6.3 版本开始有效：

services.AddSwaggerGen(options =>
{
    options.UseOneOfForPolymorphism();
    options.SelectDiscriminatorNameUsing(_ => "type");
});

如何使用 Swashbuckle 在 Swagger API 文档/OpenAPI 规范中包含子类？

How do I include subclasses in Swagger API documentation/ OpenAPI specification using Swashbuckle?

c#

api

subclassing

swagger

openapi