CSharpEssentials.AspNetCore.Swashbuckle 6.3.0

CSharpEssentials.AspNetCore.Swashbuckle

Swashbuckle (Swagger) integration for CSharpEssentials.AspNetCore: versioned Swagger setup, schema ids and security schemes.

One host, one OpenAPI package: reference either CSharpEssentials.AspNetCore.Swashbuckle (Swashbuckle) or CSharpEssentials.AspNetCore.OpenApi (Microsoft.AspNetCore.OpenApi), never both. Both use Microsoft.OpenApi 2.x.

Installation

dotnet add package CSharpEssentials.AspNetCore.Swashbuckle

Targets net8.0, net9.0, net10.0 and net11.0 with Swashbuckle.AspNetCore 10.2.3 or later (below 11) and Microsoft.OpenApi 2.x (2.7.5 or later) on every target. Filters and MapType factories you add next to these use the Microsoft.OpenApi 2.x model (using Microsoft.OpenApi;, IOpenApiSchema, JsonSchemaType, JsonNode).

Swagger with Versioning

using CSharpEssentials.AspNetCore; // AddSwagger, DefaultConfigureSwaggerOptions, SecuritySchemes, UseVersionableSwagger

builder.Services.AddSwagger<DefaultConfigureSwaggerOptions>(
    SecuritySchemes.JwtBearerSchemeName,
    SecuritySchemes.JwtBearerTokenSecurity);

var app = builder.Build();
app.UseVersionableSwagger();

The first argument is the id of the security scheme in components.securitySchemes; every operation requires it. AddSwagger includes the XML documentation file of every assembly that declares an endpoint (controllers and Minimal API handlers), plus the optional assembly argument. Missing files are skipped.

Optional route parameters

OpenAPI requires every path parameter to be required: true, so a route with an optional segment ({id?}, {id:int?}, {page=1}) cannot be described on one path. AddSwagger describes it on several paths, one per form:

[HttpGet("api/archive/{year?}/{month?}", Name = "GetArchive")]

• Each form is a full copy of the operation (tags, security, request body, responses, extensions) without the omitted parameters; every path parameter is required: true, without allowEmptyValue, a null type or default, or a {"type": "null"} member in oneOf or anyOf.
• Only optional parameters at the end of the route are split, up to three. An optional parameter followed by a required segment (api/{tenant?}/orders), a route with more than three trailing optional parameters and a catch-all parameter ({*rest}, {**path}) keep one path with the parameters marked required.
• A route with more than three trailing optional parameters is logged as a warning (once per document, path and method) through the host's ILoggerFactory, so the missing shorter forms do not go unnoticed. Without an ILoggerFactory nothing is logged.
• A form whose path and method another operation already has ([HttpGet("api/orders")] next to [HttpGet("api/orders/{id?}")]) is skipped; the other operation stays.
• The full form keeps the operationId; a shorter form gets {operationId}Without{Param} (And between parameters), or none when the full form has none. A generated operationId that another operation already uses throws InvalidOperationException when the document is generated; rename one of them or pass a selector.
• Controller and Minimal API routes are handled the same way.
• Forms are found by matching the trailing {name} segments of the path that SwaggerGenOptions.PathGroupSelector returns; a custom selector whose paths do not end with those segments falls back to required-only.

using CSharpEssentials.AspNetCore; // AddOptionalRouteParameters, OptionalRouteParameterMode
using Swashbuckle.AspNetCore.SwaggerGen; // SwaggerGenOptions

// Split paths with your own operationIds for the shorter forms
builder.Services.Configure<SwaggerGenOptions>(o => o.AddOptionalRouteParameters(
    operationIdSelector: (operationId, omitted) => $"{operationId}_{string.Join("_", omitted)}"));

// Or keep one path per operation and only mark the parameters required
builder.Services.Configure<SwaggerGenOptions>(o =>
    o.AddOptionalRouteParameters(OptionalRouteParameterMode.RequiredOnly));

AddOptionalRouteParameters replaces the earlier setting, so call it after AddSwagger. OptionalRouteParameterMode.LegacyNonCompliant (obsolete) restores the output of 6.0.0 and earlier: required: false, allowEmptyValue: true and a nullable schema with a null default on the path parameter, which is not valid OpenAPI. See docs/migration/v6-optional-route-parameters.md.

Enum schemas

using CSharpEssentials.AspNetCore; // AddEnumConventions for IServiceCollection and SwaggerGenOptions

builder.Services.AddEnumConventions();
builder.Services.AddSwaggerGen(o => o.AddEnumConventions()); // AddSwagger calls it

Enums handled by the enum conventions ([StringEnum] or generated metadata) are described the way they are written: one component per enum with the wire names in enum, x-enum-varnames, x-enum-descriptions, x-enum-numeric-values and a value table appended to your description (obsolete members (deprecated), the [EnumFallback] member Response only:). default is the wire name, [Flags] enums are arrays with uniqueItems: true, and nullable is written where the enum is used (allOf + nullable: true, OpenAPI 3.0). Keep OpenAPI 3.0, the Swashbuckle default. The enum filters always write the 3.0 shape (a filter cannot see the version UseSwagger serializes), and with UseSwagger(o => o.OpenApiVersion = OpenApiSpecVersion.OpenApi3_1) a nullable enum usage, and (with OptionalRouteParameterMode.LegacyNonCompliant) an optional route parameter whose schema is a $ref, is serialized as {"type": "null", "allOf": [{"$ref": ...}]}: no value matches both type: "null" and the referenced component, so the schema is unsatisfiable and validators and client generators reject null and every enum value.

A document whose operations all write numbers describes the enums as integer; a document that mixes formats describes strings and marks each number operation with x-enum-wire-format: number and a note; it also logs one warning per enum used in both formats (once per document). Header selected operations get x-enum-wire-format-header and a note; a selector that throws for a request without the header is described with the global WriteAs format and logged once as a warning. Enums without [StringEnum] or metadata keep the Swashbuckle schema.

The schemas match those of CSharpEssentials.AspNetCore.OpenApi (both are compared with the same golden files).

From 5.x

5.x pinned Swashbuckle.AspNetCore 8.x/9.x and Microsoft.OpenApi 1.x. 6.0 needs Swashbuckle.AspNetCore 10 and Microsoft.OpenApi 2.x on every target:

• AddSwagger<T>(securityScheme, assembly) is now AddSwagger<T>(securitySchemeName, securityScheme, assembly): Microsoft.OpenApi 2.x has no Reference on OpenApiSecurityScheme, so the scheme id is an argument. SecuritySchemes.JwtBearerSchemeName is "Bearer", the id 5.x used.
• SecuritySchemes.JwtBearerTokenSecurity no longer sets Reference.
• Your own Swashbuckle filters move to the Swashbuckle 10 / Microsoft.OpenApi 2.x API: using Microsoft.OpenApi; (no .Models/.Any), ISchemaFilter.Apply(IOpenApiSchema, ...), JsonSchemaType instead of type strings, JsonNode instead of IOpenApiAny, JsonNodeExtension for extensions.
• EnumSchemaFilter is sealed and its Apply takes IOpenApiSchema.
• A ConfigureSwaggerOptions subclass imports OpenApiInfo and OpenApiLicense from Microsoft.OpenApi (was Microsoft.OpenApi.Models).
• An optional route parameter ({id?}) whose schema is a $ref is written as allOf: [$ref] + nullable: true, since a $ref cannot carry siblings in OpenAPI 3.0. From 6.1.0 this applies to OptionalRouteParameterMode.LegacyNonCompliant only; see Optional route parameters.
• An enum property with its own XML <summary> is written as allOf: [$ref] + description; a property without one stays a plain $ref.

See docs/migration/v5-to-v6.md for the full list.

From 4.x

The Swagger code moved here from CSharpEssentials.AspNetCore; namespaces and the AddSwagger API are unchanged. EnumSchemaFilter now takes an IServiceProvider (Swashbuckle creates it); register it with AddEnumConventions() instead of SchemaFilter<EnumSchemaFilter>().