routing-controllers-openapi

Runtime OpenAPI v3 schema generation for routing-controllers.

Installation

yarn add routing-controllers-openapi

Usage

import { getMetadataArgsStorage } from 'routing-controllers'
import { routingControllersToSpec } from 'routing-controllers-openapi'

// Define your controllers as usual:

@JsonController('/users')
class UsersController {
  @Get('/:userId')
  getUser(@Param('userId') userId: string) {
    // ...
  }

  @HttpCode(201)
  @Post('/')
  createUser(@Body() body: CreateUserBody) {
    // ...
  }
}

// Generate a schema:

const storage = getMetadataArgsStorage()
const spec = routingControllersToSpec(storage)
console.log(spec)

prints out the following specification:

{
  "components": {
    "schemas": {}
  },
  "info": {
    "title": "",
    "version": "1.0.0"
  },
  "openapi": "3.0.0",
  "paths": {
    "/users/{userId}": {
      "get": {
        "operationId": "UsersController.getUser",
        "parameters": [
          {
            "in": "path",
            "name": "userId",
            "required": true,
            "schema": {
              "type": "string"
            }
          }
        ],
        "responses": {
          "200": {
            "content": {
              "application/json": {}
            },
            "description": "Successful response"
          }
        },
        "summary": "List users",
        "tags": [
          "Users"
        ]
      }
    },
    "/users/": {
      "post": {
        "operationId": "UsersController.createUser",
        "requestBody": {
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/CreateUserBody"
              }
            }
          },
          "description": "CreateUserBody",
          "required": false
        },
        "responses": {
          "201": {
            "content": {
              "application/json": {}
            },
            "description": "Successful response"
          }
        },
        "summary": "Create user",
        "tags": [
          "Users"
        ]
      }
    }
  }
}

Check /sample for a complete sample application.

Configuration

routingControllersToSpec has the following type signature:

export function routingControllersToSpec(
  storage: MetadataArgsStorage,
  routingControllerOptions: RoutingControllersOptions = {},
  additionalProperties: Partial<OpenAPIObject> = {}
): OpenAPIObject

routingControllerOptions refers to the options object used to configure routing-controllers. Pass in the same options here to have your routePrefix and defaults options reflected in the resulting OpenAPI spec.

additionalProperties is a partial OpenAPI object that gets merged into the result spec. You can for example set your own info or components keywords here.

Validation classes

Use class-validator-jsonschema to convert your validation classes into OpenAPI-compatible schemas:

import { validationMetadatasToSchemas } from 'class-validator-jsonschema'

// ...

const schemas = validationMetadatasToSchemas(metadatas, {
  refPointerPrefix: '#/components/schemas/'
})

const spec = routingControllersToSpec(storage, routingControllerOptions, {
  components: { schemas },
  info: { title: 'My app', version: '1.2.0' }
})

Decorating with additional keywords

Use the @OpenAPI decorator to supply your actions with additional keywords:

import { OpenAPI } from 'routing-controllers-openapi'

@JsonController('/users')
export class UsersController {

  @Get('/')
  @OpenAPI({
    description: 'List all available users',
    responses: {
      '400': {
        description: 'Bad request'
      }
    }
  })
  listUsers() {
    // ...
  }
}

The parameter object consists of any number of properties from the Operation object. These properties are then merged into the spec, overwriting any existing values.

Alternatively you can call @OpenAPI with a function of type (source: OperationObject, route: IRoute) => OperationObject, i.e. a function receiving the existing spec as well as the target route, spitting out an updated spec. This function parameter can be used to implement for example your own merging logic or custom decorators.

Multiple @OpenAPI decorators

A single handler can be decorated with multiple @OpenAPIs. Note though that since decorators are applied top-down, any possible duplicate keys are overwritten by subsequent decorators:

  @OpenAPI({
    summary: 'This value will be overwritten!',
    description: 'This value will remain'
  })
  @OpenAPI({
    summary: 'This value will remain'
  })
  listUsers() {
    // ...
  }

Multiple @OpenAPIs are merged together with lodash/merge which has a few interesting properties to keep in mind when it comes to arrays. Use the function parameter described above when strict control over merging logic is required.

Class @OpenAPI decorator

Using @OpenAPI on the controller class effectively applies given spec to each class method. Method-level @OpenAPIs are merged into class specs, with the former having precedence:

@OpenAPI({
  security: [{ basicAuth: [] }] // Applied to each method
})
@JsonController('/users')
export class UsersController {
  // ...
}

Annotating response schemas

Extracting response types automatically in runtime isn't currently allowed by Typescript's reflection system. Specifically the problem is that routing-controllers-openapi can't unwrap generic types like Promise or Array: see e.g. here for discussion. As a workaround you can use the @ResponseSchema decorator to supply the response body schema:

import { ResponseSchema } from 'routing-controllers-openapi'

@JsonController('/users')
export class UsersController {

  @Get('/:id')
  @ResponseSchema(User)
  getUser() {
    // ...
  }
}

@ResponseSchema takes as an argument either a class-validator class or a plain string schema name. You can also supply an optional secondary options argument:

  @Post('/')
  @ResponseSchema(User, {
    contentType: 'text/csv',
    description: 'A list of created user objects',
    isArray: true
    statusCode: '201'})
  createUsers() {
    // ...
  }

contentType and statusCode default to routing-controller's @ContentType and @HttpCode values. To specify a response schema of an array, set options.isArray as true. You can also annotate a single handler with multiple ResponseSchemas to specify responses with different status codes.

Note that when using @ResponseSchema together with @JSONSchema, the outer decorator will overwrite keys of inner decorators. So in the following example, information from @ResponseSchema would be overwritten by @JSONSchema:

@JSONSchema({responses: {
  '200': {
    'content': {
      'application/json': {
        schema: {
          '$ref': '#/components/schemas/Pet'
        }
      }
    ]
  }
}})
@ResponseSchema(SomeResponseObject)
handler() { ... }

Supported features

• @Controller/@JsonController base route and default content-type
• options.routePrefix
• @Get, @Post and other action decorators
• Parse path parameters straight from path strings and optionally supplement with @Param decorator
  • Regex and optional path parameters (e.g. /users/:id(\d+)/:type?) are also supported
• @QueryParam and @QueryParams
• @HeaderParam and @HeaderParams
• @Body and @BodyParam
• Parse response keywords from @HttpCode and @ContentType values
• Global options.defaults.paramOptions.required option and local override with {required: true} in decorator params
• Parse summary, operationId and tags keywords from controller/method names

Future work

• Support for routing-controller's authorization features

Feel free to submit a PR!

Related projects

• Inspired by tsoa and trafficlight
• Include your Mongoose models in the spec with mongoose-schema-jsonschema
• Generate JSON schema from your Typescript sources with typescript-json-schema
• openapi3-ts provides handy OpenAPI utilities for Typescript
• Convert OpenAPI 3 spec to Swagger 2 with api-spec-converter
• Generate Typescript interface definitions from SQL database schema with schemats