@airtasker/spot

Spot

Spot ("Single Point Of Truth") is a concise, developer-friendly way to describe your API contract.

Leveraging the TypeScript syntax, it lets you describe your API and generate any other API contract formats you need (OpenAPI, Swagger, JSON Schema, Pact, API Blueprint), client SDKs (TypeScript, Swift, Kotlin) or even server boilerplate (e.g. Express).

You don't need to use TypeScript in your codebase to benefit from using Spot.

Example of an API definition file api.ts which defines a single POST endpoint to create a user:

import { api, endpoint, request, response } from "@airtasker/spot";

@api({
  name: "My API",
  description: "My really cool API"
})
class Api {
  @endpoint({
    method: "POST",
    path: "/users"
  })
  createUser(@request req: CreateUserRequest): CreateUserResponse {
    return response();
  }
}

interface CreateUserRequest {
  firstName: string;
  lastName: string;
}

interface CreateUserResponse {
  success: boolean;
}

You can pass the definition above to a generator by simply running:

npx @airtasker/spot generate --api api.ts

This is work in progress as of 14 Nov 2018:

• Functional TypeScript DSL
• Support for multiple files (using import statements)
• OpenAPI 3 generator
• OpenAPI 2 generator
• JSON Schema generator
• Pact generator
• API Blueprint generator
• TypeScript axios-based client generator
• TypeScript express-based server boilerplate generator

• Spot
• Usage
• Commands

Usage

To get started and set up an API declaration in the current directory, run:

npx @airtasker/spot init

You can then run a generator with:

npx @airtasker/spot generate --api api.ts

@api

Define an API. This is required and must only be defined once:

import { api } from "@airtasker/spot";

@api({
  name: "My API",
  description: "My really cool API"
})
class MyAPI {}

Field	Description
name	(required) Name of the API
description	(required) Description of the API

@endpoint

Define a HTTP endpoint for the API. An endpoint describes a particular HTTP action on a URL path:

import { endpoint, header, pathParam, queryParam, request, response, specificError } from "@airtasker/spot";

class MyUserEndpoints {
  // GET /users expects a mandatory `search_term` query parameter and returns a list of users.
  @endpoint({
    method: "GET",
    path: "/users",
    description: "Retrieve all users",
    tags: ["Users"]
  })
  getUsers(@queryParam({ description: "Search term" }) search_term: Optional<string>): UserResponse[] {
    return response();
  }

  // GET /users/:id returns a user by their unique identifier.
  @endpoint({
    method: "GET",
    path: "/users/:id",
    description: "Get user by id",
    tags: ["Users"]
  })
  getUser(@pathParam({ description: "Unique user identifier" }) id: string): UserResponse {
    return response();
  }

  // POST /users creates a user, expecting an authorization token to be present.
  @endpoint({
    method: "POST",
    path: "/users",
    description: "Create a user",
    tags: ["Users"]
  })
  @specificError<ApiErrorResponse>({
    name: "unauthorized",
    statusCode: 401
  })
  createUser(
    @request req: CreateUserRequest,
    @header({
      name: "Authorization",
      description: "This is the authorization token"
    })
    authToken: Optional<string>
  ): CreateUserResponse {
    return response();
  }
}

interface User {
  firstName: string;
  lastName: string;
}

type UserResponse = User;
type UserListResponse = User[];

interface CreateUserRequest {
  firstName: string;
  lastName: string;
}

interface CreateUserResponse {
  success: boolean;
}

interface ApiErrorResponse {
  message: string;
}

Field	Default	Description
method		(required) HTTP method
path		(required) URL path
description	""	Description of the endpoint
requestContentType	application/json	Content type of the request body
successStatusCode	200	HTTP status code for a successful response
tags		List of tags used for endpoint grouping in documentation

@request

Define a request body for requests that require one. This is commonly used for POST and PUT requests and is not allowed for GET requests:

class MyUserEndpoints {
  //...
  @endpoint({
    method: "POST",
    path: "/users"
  })
  createUser(
    @request req: CreateUserRequest
  ): UserResponse {
    return response();
  }

  @endpoint({
    method: "PUT",
    path: "/users/:id"
  })
  updateUser(
    @pathParam({ description: "User unique identifier" }) id: string,
    @request req: UpdateUserRequest
  ): UserResponse {
    return response();
  }
  //...
}

interface CreateUserRequest {
  firstName: string;
  lastName: string;
}

interface UpdateUserRequest {
  lastName: string;
}

@header

Define a request header. @header can be used multiple times to define multiple headers:

  //...
  @endpoint({
    method: "POST",
    path: "/users",
    description: "Create a user"
  })
  createUser(
    @request req: CreateUserRequest,
    @header({
      name: "Authorization",
      description: "This is the authorization token"
    })
    authToken: Optional<string>
  ): CreateUserResponse {
    return response();
  }
  //...

Field	Description
name	(required) Name of the header
description	Description of the header

@pathParam

Define path parameters that appear in the path provided in @endpoint(). For example if the path is /users/:id, the endpoint method must define a matching argument with @pathParam() id: string::

  //...
  @endpoint({
    method: "GET",
    path: "/users/:id",
    description: "Get user by id"
  })
  getUser(@pathParam({ description: "Unique user identifier" }) id: string): UserResponse {
    return response();
  }
  //...

Note: the name of the argument must match the name of the path parameter.

Field	Description
description	Description of the path parameter

@queryParam

Define query parameters. @queryParam can be used multiple times to define multiple query parameters:

  //...
  @endpoint({
    method: "GET",
    path: "/users",
    description: "Retrieve all users"
  })
  getUsers(@queryParam({ description: "Search term" }) search_term: Optional<string>): UserResponse[] {
    return response();
  }
  //...

Note: the name of the argument must match the name of the query parameter.

Field	Description
description	Description of the query parameter

@specificError<T>

Define a known error for the endpoint. @specificError can be used multiple times to define multiple errors. T must be replaced with the response type when the error occurs, for example @specificError<UnauthorizedErrorResponse>:

  //...
  @endpoint({
    method: "POST",
    path: "/users",
    description: "Create a user"
  })
  @specificError<UnauthorizedErrorResponse>({
    name: "unauthorized",
    statusCode: 401
  })
  createUser(
    //...
  ): CreateUserResponse {
    return response();
  }
  //...

Field	Description
name	(required) Name of the error
statusCode	(required) HTTP status code for the error

@genericError<T>

Define a default error for the endpoint. This can only be used once for an @endpoint. T must be replaced with the response type when the error occurs, for example @genericError<ApiErrorResponse>:

  //...
  @endpoint({
    method: "POST",
    path: "/users",
    description: "Create a user"
  })
  @genericError<ApiErrorResponse>()
  createUser(
    //...
  ): CreateUserResponse {
    return response();
  }
  //...

Matcher Types

Type	Description	Example
string	A string value	name: string
number	A number value	numPencils: number
Int32	A 32-bit integer	age: Int32
Int64	A 64-bit integer	numAtoms: Int64
Float	A 32-bit floating point number	weight: Float
Double	A 64-bit floating point number	price: Double
boolean	A boolean value	isAdmin: boolean
Date	ISO-8601 string representation of a date	dateOfBirth: Date
DateTime	ISO-8601 string representation of a date-time	createdAt: DateTime
Constant	An exact value	role: "admin"
Optional<T>	An optional value	role: Optional<string>
Union	One-of	role: "admin" | "member", param: string | number
Array	Collection	nicknames: string[]
Object	An object matcher	person: { firstName: string, lastName: string }

Suppported HTTP Methods

GET, HEAD, POST, PUT, DELETE, CONNECT, OPTIONS, TRACE, PATCH

Commands

• spot generate
• spot help [COMMAND]
• spot init
• spot validate SPOT_CONTRACT

spot generate

Runs a generator on an API. Used to produce client libraries, server boilerplates and well-known API contract formats such as OpenAPI.

USAGE
  $ spot generate

OPTIONS
  -a, --api=api              (required) Path to a TypeScript API definition
  -g, --generator=generator  Generator to run
  -h, --help                 show CLI help
  -l, --language=language    Language to generate
  -o, --out=out              Directory in which to output generated files

EXAMPLE
  $ spot generate --language typescript --generator axios-client --out src/
  Generated the following files:
  - src/types.ts
  - src/validators.ts
  - src/client.ts

See code: build/cli/src/commands/generate.js

spot help [COMMAND]

display help for spot

USAGE
  $ spot help [COMMAND]

ARGUMENTS
  COMMAND  command to show help for

OPTIONS
  --all  see all commands in CLI

See code: @oclif/plugin-help

spot init

Generates the boilerplate for an API.

USAGE
  $ spot init

OPTIONS
  -h, --help  show CLI help

EXAMPLE
  $ spot init
  Generated the following files:
  - api.ts
  - tsconfig.json
  - package.json

See code: build/cli/src/commands/init.js

spot validate SPOT_CONTRACT

Validate a Spot contract

USAGE
  $ spot validate SPOT_CONTRACT

ARGUMENTS
  SPOT_CONTRACT  path to Spot contract

OPTIONS
  -h, --help  show CLI help

EXAMPLE
  $ spot validate api.ts

See code: build/cli/src/commands/validate.js