Add Documents Using Go

brief introduction

Documentation is essential for API services.

Documents, however, are annoying, especially synchronous updates. If you choose handwritten documents, you often forget to update them.
Or in the early stages of high-speed development, there is no time to update the document.

A more popular way now is to use the document as a comment, to synchronize updates with the code.
Update in real time using auto-generated documents.

Another concept is that a document is a test so that it can be viewed as well as used. For API documents,
It's a huge convenience. With it, you don't have to look at the documentation anymore while you're driving the Postman experiment.

This is it. swagger.

swagger start

swagger provides many tools for creating API documents, especially the RESTful APIs standard.

This RESTful APIs standard, also known as OpenAPI Specification, currently has two specifications.
2.0 and 3.0.Most implementations are based on 2.0.

This project also uses the 2.0 specification.

Installing the swag tool also allows you to download precompiled binaries directly.

go get -u

Running swag init under the project root directory should create the docs directory.

swag init

Install swag-gin.

go get -u
go get -u

At this point, the dependencies have been installed and all that remains is documentation.

Write documentation

After all, it is a specification, or you should learn how to use it. If you are interested, you can see
Original specification.

Just look at the swag library documentation here.
Declarative Comments Format.

The main format is @key value, which is a key-value pair.
The final parse results in an entire json file.

Write a comment for the main function that defines the general information for the API.

// @title Apiserver API
// @version 1.0
// @description This is a simple api server.

// coolcat
// @contact.url

// Apache 2.0
// @license.url

// @host
// @BasePath /v1

// @securityDefinitions.apikey ApiKeyAuth
// @in header
// @name Authorization
func main() {

In the note above, there are four main parts which define:

  • Title, Version Number, Description
  • Contact Information
  • license
  • Security Definition

Update router.go to combine swagger with gin:

import {
  swaggerFiles ""
  ginSwagger ""
    // docs is generated by Swag CLI, you have to import it.
  _ ""

func Load(g *gin.Engine, mw ...gin.HandlerFunc) *gin.Engine {
  // swagger document
    // The url pointing to API definition
    // /swagger/index.html
    url := ginSwagger.URL("/swagger/doc.json")
    g.GET("/swagger/*any", ginSwagger.WrapHandler(swaggerFiles.Handler, url))

The rest is to document each interface. For example, the documentation for the login interface is as follows:

// @Summary login
// @Description login, get token
// @Tags login
// @Accept  json
// @Produce  json
// @Param body body model.UserModel true "User login""
// @Success 200 {object} model.Token "{"code":0,"message":"OK","data":{"token":"name"}}"
// @Router /login [post]
func Login(ctx *gin.Context) {

Here the basic properties of the interface are defined, including path, request type, output on success, output format, etc.

// @Summary Get Users
// @Description Gets User Information from Database
// @Tags user
// @Accept  json
// @Produce  json
// @Security ApiKeyAuth
// @Param id path uint64 true "user id in database"
// @Success 200 {object} model.UserModel "{"code":0,"message":"OK","data": {}}"
// @Router /user/{id} [get]
func Get(ctx *gin.Context) {

The get interface has one more parameter @Security ApiKeyAuth than the login interface above to define the authentication method.
The authentication method ApiKeyAuth has already been defined in the main function's comment and can be specified directly here.

After each document update, you need to run swag init to update the docs directory.

After you start the server, you can access the API documentation on /swagger/index.html.

More documentation comments can be viewed in the source code.


After the document is written, you need to run the swag init update, which can be defined in the Makefile file.

build: updoc
    go build -ldflags ${ldflags} ./
run: updoc
    go run -ldflags ${ldflags} ./
docker: updoc
    go run -ldflags ${ldflags} ./ -c ./conf/config_docker.yaml
    go mod download
    go get -u
    swag init

Run make run, then you can open http://localhost:8081/swagger/index.html in your browser and view the document.
Open http://localhost:8081/swagger/doc.json to view the generated JSON file.
With this json file, you can view the API documentation in other swagger gui s.


swagger provides great convenience for writing documents. Good tools, but more importantly, persistence.

Code for current section

As Version v0.16.0

Keywords: Go JSON github Apache Database

Added by ztkirby on Sun, 10 Nov 2019 03:16:06 +0200