GoREST

A type-safe HTTP API implementation tool for Go ( inspired by Square's Retrofit library )

Installation

$ go get github.com/jsaund/gorest

Features

GoREST transforms your HTTP API Interface definition in to a type-safe request and response implementation with both synchronous and asynchronous execution functions. Defining the API as an interface provides you the ability to create mock objects and testable code. The request implemenation also maintains combatability with gomobile so you can generate HTTP API implementations for your cross-platform SDK written in Go!

The tool is design to accept a .go file that has an interface with the support annotations. The tool parses the interface and generates the respective implementation. The Request is generated as a Builder. The builder can be executed using either the Run or RunAsync function for either synchronous or asynchronous execution, respectively.

Defining an HTTP API

Each file containing a HTTP API definition should contain the following go:generate tag:

//go:generate $GOPATH/src/github.com/jsaund/gorest/gorest -input [NAME OF GO FILE API DEFINITION] -output [NAME OF GO FILE OUTPUT] -pkg [YOUR PACKAGE NAME]

Request Method

Every interface must have a HTTP annotation that provides the request method and relative URL. There are four supported HTTP method annotations: GET, POST, POST_FORM, PUT, DELETE. Example:

// @GET("/photos")
type GetPhotosRequestBuilder interface {
    // ... function declarations for request parameters
}

URL Manipulation

A request URL can be updated dynamically using replacement blocks and parameters on the method. A replacement block is an alphanumeric string surrounded by { and }. A corresponding parameter must be annotated with @PATH using the same string.

// @GET("/photos/{id}")
type GetPhotoDetailsRequestBuilder interface {
    // @PATH("id")
    PhotoID(id string) GetPhotoDetailsRequestBuilder

    // ... function declarations for request parameters
}

Query Parameters

In addition to updating a request URL dynamically, you can also supply query parameters using the @QUERY annotation.

// @GET("/photos/{id}")
type GetPhotoDetailsRequestBuilder interface {
    // @PATH("id")
    PhotoID(id string) GetPhotoDetailsRequestBuilder

    // @QUERY("image_size")
    ImageSize(size int8) GetPhotoDetailsRequestBuilder

    // @QUERY("comments")
    Comments(include int8) GetPhotoDetailsRequestBuilder
}

Request Body

To specifcy an object for use as an HTTP request body you must use the @BODY annotation. Only one @BODY annotation must be used per request. The object must support JSON serialization.

// @POST("/photos")
type PostPhotoRequestBuilder interface {
    // @BODY("photo")
    PhotoMetadata(metadata Metadata) PostPhotoRequestBuilder
}

Form Encoded

To send form-encoded data you must first use the @POST_FORM HTTP annotation for the interface declaration and then declare any key-value pair of form data using the @FIELD annotation.

// @POST_FORM("/photos/{id}/comments")
type PostCommentRequestBuilder interface {
	// @PATH("id")
	PhotoID(id string) PostCommentRequestBuilder

	// @FIELD("body")
	Body(body string) PostCommentRequestBuilder
}

Multipart Data

Multipart requests can be defined with the @PART annotation. This is applicable for only @POST or @PUT operations.

// @POST("/upload")
type PostUploadPhotoRequestBuilder interface {
	// @PART("photo_id")
	PhotoID(id string) PostUploadPhotoRequestBuilder

	// @PART("file")
	File(body string) PostUploadPhotoRequestBuilder
}

As of the current version, this operation is considered fairly expensive as it requires copying the entire payload of the part in to memory and marshaling it to the Go SDK. This will be improved in the future to stream data.

Headers

You can also supply custom header key-value pair definitions using the @HEADER annotation.

// @GET("/users/{id}/friends")
type GetUserFriendsRequestBuilder interface {
	// @PATH("photo_id")
	PhotoID(id string) GetUserFriendsRequestBuilder

	// @HEADER("User-Agent")
	UserAgent(agent string) GetUserFriendsRequestBuilder
}

Note that header names will append to any existing values associated with name. Supplying the empty string for the header value will remove the header key-value pair from the map.

Contributors

Contributors wanted! Please feel free to create an issue for features or improvements or open a pull request with testing.

License

GoREST is MIT License.