herodot

---

Herodot is a lightweight SDK for writing RESTful responses. It is comparable to render but provides easier error handling. The error model implements the well established Google API Design Guide. Herodot currently supports only JSON responses but can be extended easily.

Herodot is used by ORY Hydra and serves millions of requests already.

Installation

Herodot is versioned using go modules and works best with pkg/errors. To install it, run

go get -u github.com/ory/herodot

herodot/v2

The v2 directory contains the module github.com/ory/herodot/v2. It identifies errors by a domain and a reason from a proto catalog and renders them in the AIP-193 shape. This module bridges to it:

• herodot.Legacy(outer, inner) wraps a v2 error in the DefaultError that was returned before, so that legacy responses stay byte-equal during the migration.
• DefaultError implements herodotv2.Classifier, so herodotv2.From classifies it under the legacy.ory.com domain.
• JSONWriter renders v2 errors that aren't wrapped in a DefaultError in the legacy shape, and JSONWriter.Recorder and the Recording*Interceptor functions record each error response with its AIP shadow rendering.

Upgrading

Tips on upgrading can be found in UPGRADE.md

Usage

Using Herodot is straightforward. The examples below will help you get started.

JSON

Herodot supplies an interface, allowing to return errors in many data formats like XML and others. Currently, it supports only JSON.

Write responses

var hd = herodot.NewJSONWriter(nil)

func GetHandler(rw http.ResponseWriter, r *http.Request) {
	// run your business logic here
	hd.Write(rw, r, map[string]interface{}{
	    "key": "value"
	})
}

type MyStruct struct {
	Key string `json:"key"`
}

func GetHandlerWithStruct(rw http.ResponseWriter, r *http.Request) {
	// business logic
	hd.Write(rw, r, &MyStruct{Key: "value"})
}

func PostHandlerWithStruct(rw http.ResponseWriter, r *http.Request) {
	// business logic
	hd.WriteCreated(rw, r, "/path/to/the/resource/that/was/created", &MyStruct{Key: "value"})
}

func SomeHandlerWithArbitraryStatusCode(rw http.ResponseWriter, r *http.Request) {
	// business logic
	hd.WriteCode(rw, r, http.StatusAccepted, &MyStruct{Key: "value"})
}

func SomeHandlerWithArbitraryStatusCode(rw http.ResponseWriter, r *http.Request) {
	// business logic
	hd.WriteCode(rw, r, http.StatusAccepted, &MyStruct{Key: "value"})
}

Dealing with errors

var writer = herodot.NewJSONWriter(nil)

func GetHandlerWithError(rw http.ResponseWriter, r *http.Request) {
    if err := someFunctionThatReturnsAnError(); err != nil {
        hd.WriteError(w, r, err)
        return
    }

    // ...
}

func GetHandlerWithErrorCode(rw http.ResponseWriter, r *http.Request) {
    if err := someFunctionThatReturnsAnError(); err != nil {
        hd.WriteErrorCode(w, r, http.StatusBadRequest, err)
        return
    }

    // ...
}

Errors

Herodot implements the error model of the well established Google API Design Guide. Additionally, it makes the fields request and reason available. A complete Herodot error response looks like this:

{
  "error": {
    "code": 404,
    "status": "some-status",
    "request": "foo",
    "reason": "some-reason",
    "details": [{ "foo": "bar" }],
    "message": "foo"
  }
}

To add context to your errors, implement herodot.ErrorContextCarrier. If you only want to set the status code of errors implement herodot.StatusCodeCarrier.