OpenAPITools 能够根据 REST API 形容文件，主动生成服务端桩（Stub）代码、客户端 SDK 代码，及文档等。其是社区版的 Swagger ，差别可见：OpenAPI Generator vs Swagger Codegen。
本文将从零开始设计和编写 API 文件，并生成 Go Gin 服务端代码，与 Python SDK 代码。更多语言或框架，也是一样操作的。
疾速开始
先相熟下工具，间接用官网 Docker 镜像生成 Petstore 样例的 Go SDK 代码：
docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli generate \-i https://raw.githubusercontent.com/openapitools/openapi-generator/master/modules/openapi-generator/src/test/resources/3_0/petstore.yaml \-g go \-o /local/out/go生成代码在当前目录的 ./out/go 。
关上 Swagger Editor File > Import URL 查看 petstore.yaml API：
查看 openapi-generator-cli 用法:
docker run --rm -it \-v "${PWD}:/local" \--entrypoint /bin/bash \openapitools/openapi-generator-cliln -s /usr/local/bin/docker-entrypoint.sh /usr/local/bin/openapi-generatoropenapi-generator helpopenapi-generator help generate入手实际
设计 RESTful API
关上 Swagger Editor 设计 API：
/albums
- GET - Get all albums
- POST - Create a new album
/albums/:id
- GET - Get an album by its id
- PUT - Update an album by its id
- DELETE - Delete an album by its id
残缺 API 形容文件见 spec/api.yaml，次要蕴含三局部：
1 头部： API 信息
openapi: 3.0.0info: title: Start OpenAPITools description: Let's practice designing our api. version: 0.1.0 license: name: MIT url: https://spdx.org/licenses/MIT.htmlservers: - url: https://github.com/ikuokuo/start-openapitools2 两头： paths 及其操作 (get, post, etc.)
paths: /albums/{id}: get: tags: - album summary: Get an album by its id operationId: getAlbum parameters: - $ref: '#/components/parameters/AlbumId' responses: 200: description: Get success, return the album content: application/json: schema: $ref: '#/components/schemas/Album' 404: description: Album not found3 底部： 可重用的 components，于文档里 $ref 援用
components: parameters: AlbumId: name: id in: path description: Album id required: true schema: type: string schemas: Album: title: Album type: object required: - title - artist - price properties: id: type: string format: uuid title: type: string maxLength: 200 minLength: 1 artist: type: string maxLength: 100 minLength: 1 price: type: number format: double minimum: 0.0 created_at: type: string format: date-time updated_at: type: string format: date-time具体阐明，请浏览 OpenAPI Specification。
在线生成代码
能够用线上服务疾速生成代码：
- latest stable version: https://api.openapi-generator...
以下则是本人入手生成的过程。
生成 Server Stub 代码
生成 Go Gin 桩（Stub）代码：
docker run --rm -it \-v "${PWD}:/local" \--entrypoint /bin/bash \openapitools/openapi-generator-cliln -s /usr/local/bin/docker-entrypoint.sh /usr/local/bin/openapi-generator# Config Options for go-gin-server# https://openapi-generator.tech/docs/generators/go-gin-serveropenapi-generator config-help -g go-gin-serveropenapi-generator generate \-g go-gin-server \-i /local/spec/swagger.yaml \-o /local/out/gin-server \--additional-properties=packageName=startapi生成内容：
❯ tree out/gin-server -aF --dirsfirstout/gin-server├── .openapi-generator/├── api/│ └── openapi.yaml├── go/│ ├── README.md│ ├── api_album.go│ ├── api_albums.go│ ├── model_album.go│ └── routers.go├── .openapi-generator-ignore├── Dockerfile└── main.go简略实现 GetAlbum 接口，位于 go/api_album.go：
// GetAlbum - Get an album by its idfunc GetAlbum(c *gin.Context) { c.JSON(http.StatusOK, Album{ Id: "3fa85f64-5717-4562-b3fc-2c963f66afa6", Title: "Start OpenAPITools", Artist: "GoCoding", Price: 0.99, CreatedAt: time.Now(), UpdatedAt: time.Now(), })}运行服务：
cd out/gin-server/# 初始化模块go mod init github.com/ikuokuo/start-openapitools/gin-servergo mod tidy# 批改 `main.go` 中的 import 门路# sw "github.com/ikuokuo/start-openapitools/gin-server/go"# 替换老本地门路go mod edit -replace github.com/ikuokuo/start-openapitools/gin-server/go=./go运行后果：
❯ go run .2021/11/05 18:20:00 Server started[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production. - using env: export GIN_MODE=release - using code: gin.SetMode(gin.ReleaseMode)[GIN-debug] GET /ikuokuo/start-openapitools/ --> github.com/ikuokuo/start-openapitools/gin-server/go.Index (3 handlers)[GIN-debug] DELETE /ikuokuo/start-openapitools/albums/:id --> github.com/ikuokuo/start-openapitools/gin-server/go.DeleteAlbum (3 handlers)[GIN-debug] GET /ikuokuo/start-openapitools/albums/:id --> github.com/ikuokuo/start-openapitools/gin-server/go.GetAlbum (3 handlers)[GIN-debug] PUT /ikuokuo/start-openapitools/albums/:id --> github.com/ikuokuo/start-openapitools/gin-server/go.PutAlbum (3 handlers)[GIN-debug] GET /ikuokuo/start-openapitools/albums --> github.com/ikuokuo/start-openapitools/gin-server/go.GetAlbums (3 handlers)[GIN-debug] POST /ikuokuo/start-openapitools/albums --> github.com/ikuokuo/start-openapitools/gin-server/go.PostAlbums (3 handlers)[GIN-debug] Listening and serving HTTP on :8080❯ curl http://localhost:8080/ikuokuo/start-openapitools/Hello World!生成 Client SDK 代码
生成 Python SDK 代码：
docker run --rm -it \-v "${PWD}:/local" \--entrypoint /bin/bash \openapitools/openapi-generator-cliln -s /usr/local/bin/docker-entrypoint.sh /usr/local/bin/openapi-generator# Config Options for python# https://openapi-generator.tech/docs/generators/pythonopenapi-generator config-help -g pythonopenapi-generator generate \-g python \-i /local/spec/swagger.yaml \-o /local/out/py-sdk \--additional-properties=packageName=startapi \--additional-properties=library=urllib3生成内容：
❯ tree out/py-sdk -aF --dirsfirstout/py-sdk├── .openapi-generator/├── docs/├── startapi/│ ├── api/│ │ ├── __init__.py│ │ ├── album_api.py│ │ └── albums_api.py│ ├── apis/│ │ └── __init__.py│ ├── model/│ │ ├── __init__.py│ │ └── album.py│ ├── models/│ │ └── __init__.py│ ├── __init__.py│ ├── api_client.py│ ├── configuration.py│ ├── exceptions.py│ ├── model_utils.py│ └── rest.py├── test/├── .gitignore├── .gitlab-ci.yml├── .openapi-generator-ignore├── .travis.yml├── README.md├── git_push.sh├── requirements.txt├── setup.cfg├── setup.py├── test-requirements.txt└── tox.ini测试 SDK 应用，调用此前实现的 GetAlbum 接口：
❯ cd out/py-sdk/❯ python - <<EOFfrom startapi import ApiClient, Configuration, apisconfig = Configuration(host="http://localhost:8080/ikuokuo/start-openapitools")with ApiClient(configuration=config) as client: api = apis.AlbumApi(client) album = api.get_album("xxxxx") print(album)EOF{'artist': 'GoCoding', 'created_at': datetime.datetime(2021, 11, 5, 18, 30, 0, 545305, tzinfo=tzoffset(None, 28800)), 'id': '3fa85f64-5717-4562-b3fc-2c963f66afa6', 'price': 0.99, 'title': 'Start OpenAPITools', 'updated_at': datetime.datetime(2021, 11, 5, 18, 30, 0, 545305, tzinfo=tzoffset(None, 28800))}最初
实际下来，感觉不错。很多场合，生成 SDK 就够用了。另外，生成自动化测试代码，也值得一试。
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