@ditsmod/openapi

You can use the @ditsmod/openapi module to create OpenAPI documentation.

Installation

npm i @ditsmod/openapi

Creation of documentation

To create individual routes, use the oasRoute decorator, in which the fourth or third parameter (if there are no guards) is the so-called Operation Object:

import { controller } from '@ditsmod/core';
import { oasRoute } from '@ditsmod/openapi';

@controller()
export class SomeController {
  // ...
  @oasRoute('GET', 'users/:username', {
    parameters: [
      {
        name: 'username',
        in: 'path',
        required: true,
        description: 'Username of the profile to get',
        schema: {
          type: 'string',
        },
      },
    ],
  })
  async getSome() {
    // ...
  }
}

Ditsmod has good support for TypeScript models for OpenAPI v3.1.0, including Operation Object, but it is not necessary to manually write the entire Operation Object directly in the code for each route. It is better to use helpers that will generate the necessary code for you, and also reduce the number of errors due to even better TypeScript support. Ditsmod has several such helpers: getParams(), getContent(), Parameters, Content. They are all imported from the @ditsmod/openapi module.

Passing Operation Object parameters

In the following example, with the helper getParams(), almost everything that we wrote manually for parameters in the previous example is recorded:

import { controller } from '@ditsmod/core';
import { oasRoute, getParams } from '@ditsmod/openapi';

@controller()
export class SomeController {
  // ...
  @oasRoute('GET', 'users/:username', {
    parameters: getParams('path', true, 'username'),
  })
  async getSome() {
    // ...
  }
}

The data type for the username parameter and its description are missing here. We recommend using a TypeScript class as a model so that you can then refer to it using helpers that can read its metadata and return ready-made JSON objects.

Creation of TypeScript models

The following example shows a model with three parameters:

import { property } from '@ditsmod/openapi';

class Params {
  @property({ description: 'Username of the profile to get.' })
  username: string;

  @property({ minimum: 1, maximum: 100, description: 'Page number.' })
  page: number;

  @property()
  hasName: boolean;
}

As you can see, to attach metadata to the model, the @property() decorator is used, where you can pass Schema Object as the first argument.

Note that in this case the type property is not specified in the metadata, as the types specified here are automatically read by helpers. However, not all types available in TypeScript can be read. For example, helpers will not be able to automatically see what type of array you are passing. This is exactly the case with enum. Also, helpers do not see whether an object's property is optional or not.

The array type or enum can be passed as the second parameter to the @property() decorator:

import { property } from '@ditsmod/openapi';

enum NumberEnum {
  one,
  two,
  three,
}

class Params {
  @property({}, { enum: NumberEnum })
  property1: NumberEnum;

  @property({}, { array: String })
  property2: string[];

  @property({}, { array: [String, Number] })
  property3: (string | number)[];

  @property({}, { array: [[String]] }) // Array in array
  property4: string[][];
}

References of some models to others are quite readable. In the following example, Model2 has a reference to Model1:

import { property } from '@ditsmod/openapi';

export class Model1 {
  @property()
  property1: string;
}

export class Model2 {
  @property()
  model1: Model1;

  @property({}, Model1)
  arrModel1: Model1[];
}

Using TypeScript models

The getParams() helper allows you to use models, and if you make a mistake in a parameter name, TypeScript will tell you about it:

import { controller } from '@ditsmod/core';
import { oasRoute, getParams } from '@ditsmod/openapi';

import { Params } from './params.js';

@controller()
export class SomeController {
  // ...
  @oasRoute('GET', '', {
    parameters: getParams('path', true, Params, 'username'),
  })
  async getSome() {
    // ...
  }
}

Here Params is a class used as a parameter model.

But the helper getParams() is not intended to be used simultaneously for mandatory and optional parameters. It also cannot pass a parameter description that differs from the parameter description in the parameter model. For such purposes, you can use another helper - Parameters:

import { controller } from '@ditsmod/core';
import { oasRoute, Parameters } from '@ditsmod/openapi';

import { Params } from './params.js';

@controller()
export class SomeController {
  // ...
  @oasRoute('GET', '', {
    parameters: new Parameters()
      .required('path', Params, 'username')
      .optional('query', Params, 'page', 'hasName')
      .getParams(),
  })
  async getSome() {
    // ...
  }
}

requestBody and responses content

Data models are also used to describe the content of requestBody, but there is one slight difference compared to parameters. By default, all model properties are optional, and to mark a particular property as required, you need to use the REQUIRED constant:

import { property, REQUIRED } from '@ditsmod/openapi';

class Model1 {
  @property()
  property1: string;
  @property({ [REQUIRED]: true })
  property2: number;
}

If this model will be used to describe requestBody, then property2 in it will be required. But if this model is used to describe parameters, the REQUIRED marker will be ignored:

class SomeController {
  // ...
  @oasRoute('GET', 'users', {
    parameters: getParams('query', false, Model1, 'property2'),
  })
  async getSome() {
    // ...
  }
}

To describe the content in requestBody and responses, there is also a helper getContent():

import { controller, Status } from '@ditsmod/core';
import { oasRoute, getContent } from '@ditsmod/openapi';

import { SomeModel } from '#models/some.js';

@controller()
export class SomeController {
  // ...
  @oasRoute('POST', '', {
    requestBody: {
      description: 'All properties are taken from Model1.',
      content: getContent({ mediaType: 'application/json', model: Model1 }),
    },
  })
  async postSome() {
    // ...
  }
}

The getContent() helper accepts a shortened version of the data when describing a single mediaType variant. If you need to describe a larger number of mediaType, you can use the Content class:

import { controller, Status } from '@ditsmod/core';
import { oasRoute, Content } from '@ditsmod/openapi';

import { SomeModel } from '#models/some.js';

@controller()
export class SomeController {
  // ...
  @oasRoute('GET', '', {
    responses: {
      [Status.OK]: {
        description: 'Description of content with this status',
        content: new Content()
          .set({ mediaType: 'application/xml', model: SomeModel })
          .set({ mediaType: 'application/json', model: SomeModel })
          .get(),
      },
    },
  })
  async getSome() {
    // ...
  }
}

OpenAPI module-level options

Tags and parameters can be passed at the module level:

import { OasOptions } from '@ditsmod/openapi';

@featureModule({
  // ...
  extensionsMeta: {
    oasOptions: {
      tags: ['i18n'],
      paratemers: new Parameters().optional('query', Params, 'lcl').describe('Internalization').getParams(),
    } as OasOptions,
  },
})
export class I18nModule {}

Helpers that return an entire Operation Object

The previous examples showed helpers that return parts of the Operation Object, but of course you can create your own helpers that return the entire Operation Object. One of the examples of the use of such helpers is shown in the RealWorld repository.

Special decorator for guards

The @ditsmod/openapi module has a special oasGuard decorator that allows you to attach OpenAPI metadata behind guards:

import { CanActivate } from '@ditsmod/core';
import { oasGuard } from '@ditsmod/openapi';

@oasGuard({
  tags: ['withBasicAuth'],
  securitySchemeObject: {
    type: 'http',
    scheme: 'basic',
    description:
      'Enter username: `demo`, password: `p@55w0rd`. For more info see ' +
      '[Authentication](https://developer.mozilla.org/en-US/docs/Web/HTTP/Authentication)',
  },
  responses: {
    [Status.UNAUTHORIZED]: {
      $ref: '#/components/responses/UnauthorizedError',
    },
  },
})
export class BasicGuard implements CanActivate {
  // ...
}

At the moment, the oasGuard decorator accepts the following data type:

interface OasGuardMetadata {
  securitySchemeObject: XSecuritySchemeObject;
  responses?: XResponsesObject;
  tags?: string[];
}

Where securitySchemeObject is of type Security Scheme Object and responses is of type Responses Object.

This guards are used in exactly the same way as "normal" guards:

import { controller } from '@ditsmod/core';
import { oasRoute } from '@ditsmod/openapi';

@controller()
export class SomeController {
  // ...
  @oasRoute('GET', 'users/:username', [BasicGuard])
  async getSome() {
    // ...
  }
}

@ditsmod/openapi

Installation​

Creation of documentation​

Passing Operation Object parameters​

Creation of TypeScript models​

Using TypeScript models​

requestBody and responses content​

OpenAPI module-level options​

Helpers that return an entire Operation Object​

Special decorator for guards​