swag

swag

Swag converts Go annotations to Swagger Documentation 2.0. We've created a variety of plugins for popular Go web frameworks. This allows you to quickly integrate with an existing Go project (using Swagger UI).

Contents

• Getting started
• Supported Web Frameworks
• How to use it with Gin
• Implementation Status
• Declarative Comments Format
  • General API Info
  • API Operation
  • Security
• Examples
  • Descriptions over multiple lines
  • User defined structure with an array type
  • Add a headers in response
  • Use multiple path params
  • Example value of struct
  • Description of struct
  • Use swaggertype tag to supported custom type
  • Add extension info to struct field
  • How to using security annotations
• About the Project

Getting started

1. Add comments to your API source code, See Declarative Comments Format.

2. Download swag by using:

$ go get -u github.com/swaggo/swag/cmd/swag

To build from source you need Go (1.9 or newer).

Or download a pre-compiled binary from the release page.

1. Run swag init in the project's root folder which contains the main.go file. This will parse your comments and generate the required files (docs folder and docs/docs.go).

$ swag init

Make sure to import the generated docs/docs.go so that your specific configuration gets init'ed. If your General API annotations do not live in main.go, you can let swag know with -g flag.

swag init -g http/api.go

swag cli

$ swag init -h
NAME:
   swag init - Create docs.go

USAGE:
   swag init [command options] [arguments...]

OPTIONS:
   --generalInfo value, -g value       Go file path in which 'swagger general API Info' is written (default: "main.go")
   --dir value, -d value               Directory you want to parse (default: "./")
   --propertyStrategy value, -p value  Property Naming Strategy like snakecase,camelcase,pascalcase (default: "camelcase")
   --output value, -o value            Output directory for all the generated files(swagger.json, swagger.yaml and doc.go) (default: "./docs")
   --parseVendor                       Parse go files in 'vendor' folder, disabled by default
   --parseDependency                   Parse go files in outside dependency folder, disabled by default

Supported Web Frameworks

• gin
• echo
• buffalo
• net/http

How to use it with Gin

Find the example source code here.

1. After using swag init to generate Swagger 2.0 docs, import the following packages:

import "github.com/swaggo/gin-swagger" // gin-swagger middleware
import "github.com/swaggo/files" // swagger embed files

1. Add General API annotations in main.go code:

// @title Swagger Example API
// @version 1.0
// @description This is a sample server celler server.
// @termsOfService http://swagger.io/terms/

// @contact.name API Support
// @contact.url http://www.swagger.io/support
// @contact.email support@swagger.io

// @license.name Apache 2.0
// @license.url http://www.apache.org/licenses/LICENSE-2.0.html

// @host localhost:8080
// @BasePath /api/v1

// @securityDefinitions.basic BasicAuth

// @securityDefinitions.apikey ApiKeyAuth
// @in header
// @name Authorization

// @securitydefinitions.oauth2.application OAuth2Application
// @tokenUrl https://example.com/oauth/token
// @scope.write Grants write access
// @scope.admin Grants read and write access to administrative information

// @securitydefinitions.oauth2.implicit OAuth2Implicit
// @authorizationurl https://example.com/oauth/authorize
// @scope.write Grants write access
// @scope.admin Grants read and write access to administrative information

// @securitydefinitions.oauth2.password OAuth2Password
// @tokenUrl https://example.com/oauth/token
// @scope.read Grants read access
// @scope.write Grants write access
// @scope.admin Grants read and write access to administrative information

// @securitydefinitions.oauth2.accessCode OAuth2AccessCode
// @tokenUrl https://example.com/oauth/token
// @authorizationurl https://example.com/oauth/authorize
// @scope.admin Grants read and write access to administrative information

// @x-extension-openapi {"example": "value on a json format"}

func main() {
	r := gin.Default()

	c := controller.NewController()

	v1 := r.Group("/api/v1")
	{
		accounts := v1.Group("/accounts")
		{
			accounts.GET(":id", c.ShowAccount)
			accounts.GET("", c.ListAccounts)
			accounts.POST("", c.AddAccount)
			accounts.DELETE(":id", c.DeleteAccount)
			accounts.PATCH(":id", c.UpdateAccount)
			accounts.POST(":id/images", c.UploadAccountImage)
		}
    //...
	}
	r.GET("/swagger/*any", ginSwagger.WrapHandler(swaggerFiles.Handler))
	r.Run(":8080")
}
//...

Additionally some general API info can be set dynamically. The generated code package docs exports SwaggerInfo variable which we can use to set the title, description, version, host and base path programatically. Example using Gin:

package main

import (
	"github.com/gin-gonic/gin"
	"github.com/swaggo/files"
	"github.com/swaggo/gin-swagger"
	
	"./docs" // docs is generated by Swag CLI, you have to import it.
)

// @contact.name API Support
// @contact.url http://www.swagger.io/support
// @contact.email support@swagger.io

// @license.name Apache 2.0
// @license.url http://www.apache.org/licenses/LICENSE-2.0.html

// @termsOfService http://swagger.io/terms/

func main() {

	// programatically set swagger info
	docs.SwaggerInfo.Title = "Swagger Example API"
	docs.SwaggerInfo.Description = "This is a sample server Petstore server."
	docs.SwaggerInfo.Version = "1.0"
	docs.SwaggerInfo.Host = "petstore.swagger.io"
	docs.SwaggerInfo.BasePath = "/v2"
	docs.SwaggerInfo.Schemes = []string{"http", "https"}
		
	r := gin.New()

	// use ginSwagger middleware to serve the API docs
	r.GET("/swagger/*any", ginSwagger.WrapHandler(swaggerFiles.Handler))

	r.Run()
}

1. Add API Operation annotations in controller code

package controller

import (
	"fmt"
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"
	"github.com/swaggo/swag/example/celler/httputil"
	"github.com/swaggo/swag/example/celler/model"
)

// ShowAccount godoc
// @Summary Show a account
// @Description get string by ID
// @ID get-string-by-int
// @Accept  json
// @Produce  json
// @Param id path int true "Account ID"
// @Success 200 {object} model.Account
// @Header 200 {string} Token "qwerty"
// @Failure 400 {object} httputil.HTTPError
// @Failure 404 {object} httputil.HTTPError
// @Failure 500 {object} httputil.HTTPError
// @Router /accounts/{id} [get]
func (c *Controller) ShowAccount(ctx *gin.Context) {
	id := ctx.Param("id")
	aid, err := strconv.Atoi(id)
	if err != nil {
		httputil.NewError(ctx, http.StatusBadRequest, err)
		return
	}
	account, err := model.AccountOne(aid)
	if err != nil {
		httputil.NewError(ctx, http.StatusNotFound, err)
		return
	}
	ctx.JSON(http.StatusOK, account)
}

// ListAccounts godoc
// @Summary List accounts
// @Description get accounts
// @Accept  json
// @Produce  json
// @Param q query string false "name search by q"
// @Success 200 {array} model.Account
// @Header 200 {string} Token "qwerty"
// @Failure 400 {object} httputil.HTTPError
// @Failure 404 {object} httputil.HTTPError
// @Failure 500 {object} httputil.HTTPError
// @Router /accounts [get]
func (c *Controller) ListAccounts(ctx *gin.Context) {
	q := ctx.Request.URL.Query().Get("q")
	accounts, err := model.AccountsAll(q)
	if err != nil {
		httputil.NewError(ctx, http.StatusNotFound, err)
		return
	}
	ctx.JSON(http.StatusOK, accounts)
}

//...

$ swag init

1. Run your app, and browse to http://localhost:8080/swagger/index.html. You will see Swagger 2.0 Api documents as shown below:

Implementation Status

Swagger 2.0 document

• Basic Structure
• API Host and Base Path
• Paths and Operations
• Describing Parameters
• Describing Request Body
• Describing Responses
• MIME Types
• Authentication
  • Basic Authentication
  • API Keys
• Adding Examples
• File Upload
• Enums
• Grouping Operations With Tags
• Swagger Extensions

Declarative Comments Format

General API Info

Example celler/main.go

Using markdown descriptions

When a short string in your documentation is insufficient, or you need images, code examples and things like that you may want to use markdown descriptions. In order to use markdown descriptions use the following annotations.

API Operation

Example celler/controller

Mime Types

swag accepts all MIME Types which are in the correct format, that is, match */*. Besides that, swag also accepts aliases for some MIME Types as follows:

Param Type

• query
• path
• header
• body
• formData

Data Type

• string (string)
• integer (int, uint, uint32, uint64)
• number (float32)
• boolean (bool)
• user defined struct

Security

Attribute

// @Param enumstring query string false "string enums" Enums(A, B, C)
// @Param enumint query int false "int enums" Enums(1, 2, 3)
// @Param enumnumber query number false "int enums" Enums(1.1, 1.2, 1.3)
// @Param string query string false "string valid" minlength(5) maxlength(10)
// @Param int query int false "int valid" mininum(1) maxinum(10)
// @Param default query string false "string default" default(A)

It also works for the struct fields:

type Foo struct {
    Bar string `minLength:"4" maxLength:"16"`
    Baz int `minimum:"10" maximum:"20" default:"15"`
    Qux []string `enums:"foo,bar,baz"`
}

Available

Future

Examples

Descriptions over multiple lines

You can add descriptions spanning multiple lines in either the general api description or routes definitions like so:

// @description This is the first line
// @description This is the second line
// @description And so forth.

User defined structure with an array type

// @Success 200 {array} model.Account <-- This is a user defined struct.

package model

type Account struct {
    ID   int    `json:"id" example:"1"`
    Name string `json:"name" example:"account name"`
}

Add a headers in response

// @Success 200 {string} string	"ok"
// @Header 200 {string} Location "/entity/1"
// @Header 200 {string} Token "qwerty"

Use multiple path params

/// ...
// @Param group_id path int true "Group ID"
// @Param account_id path int true "Account ID"
// ...
// @Router /examples/groups/{group_id}/accounts/{account_id} [get]

Example value of struct

type Account struct {
    ID   int    `json:"id" example:"1"`
    Name string `json:"name" example:"account name"`
    PhotoUrls []string `json:"photo_urls" example:"http://test/image/1.jpg,http://test/image/2.jpg"`
}

Description of struct

type Account struct {
	// ID this is userid
	ID   int    `json:"id"`
	Name string `json:"name"` // This is Name
}

Use swaggertype tag to supported custom type

#201

type TimestampTime struct {
    time.Time
}

///implement encoding.JSON.Marshaler interface
func (t *TimestampTime) MarshalJSON() ([]byte, error) {
    bin := make([]byte, 16)
    bin = strconv.AppendInt(bin[:0], t.Time.Unix(), 10)
    return bin, nil
}

func (t *TimestampTime) UnmarshalJSON(bin []byte) error {
    v, err := strconv.ParseInt(string(bin), 10, 64)
    if err != nil {
        return err
    }
    t.Time = time.Unix(v, 0)
    return nil
}
///

type Account struct {
    // Override primitive type by simply specifying it via `swaggertype` tag
    ID     sql.NullInt64 `json:"id" swaggertype:"integer"`

    // Override struct type to a primitive type 'integer' by specifying it via `swaggertype` tag
    RegisterTime TimestampTime `json:"register_time" swaggertype:"primitive,integer"`

    // Array types can be overridden using "array,<prim_type>" format
    Coeffs []big.Float `json:"coeffs" swaggertype:"array,number"`
}

#379

type CerticateKeyPair struct {
	Crt []byte `json:"crt" swaggertype:"string" format:"base64" example:"U3dhZ2dlciByb2Nrcw=="`
	Key []byte `json:"key" swaggertype:"string" format:"base64" example:"U3dhZ2dlciByb2Nrcw=="`
}

generated swagger doc as follows:

"api.MyBinding": {
  "type":"object",
  "properties":{
    "crt":{
      "type":"string",
      "format":"base64",
      "example":"U3dhZ2dlciByb2Nrcw=="
    },
    "key":{
      "type":"string",
      "format":"base64",
      "example":"U3dhZ2dlciByb2Nrcw=="
    }
  }
}

Add extension info to struct field

type Account struct {
    ID   string    `json:"id"   extensions:"x-nullable,x-abc=def"` // extensions fields must start with "x-"
}

generate swagger doc as follows:

"Account": {
    "type": "object",
    "properties": {
        "id": {
            "type": "string",
            "x-nullable": true,
            "x-abc": "def"
        }
    }
}

How to using security annotations

General API info.

// @securityDefinitions.basic BasicAuth

// @securitydefinitions.oauth2.application OAuth2Application
// @tokenUrl https://example.com/oauth/token
// @scope.write Grants write access
// @scope.admin Grants read and write access to administrative information

Each API operation.

// @Security ApiKeyAuth

Make it AND condition

// @Security ApiKeyAuth
// @Security OAuth2Application[write, admin]

About the Project

This project was inspired by yvasiyarov/swagger but we simplified the usage and added support a variety of web frameworks. Gopher image source is tenntenn/gopher-stickers. It has licenses creative commons licensing.

Contributors

This project exists thanks to all the people who contribute. [Contribute].

Backers

Thank you to all our backers! 🙏 [Become a backer]

Sponsors

Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]

License