jsonhal.go

// Package jsonhal provides structs and methods to easily wrap your own data
// in a HAL compatible struct with support for hyperlinks and embedded resources
// HAL specification: http://stateless.co/hal_specification.html
package jsonhal

import (
	"fmt"
)

// Link represents a link in "_links" object
type Link struct {
	Href  string `json:"href"`
	Title string `json:"title,omitempty"`
}

// Embedded represents a resource in "_embedded" object
type Embedded interface{}

// EmbedSetter is the interface that wraps the basic setEmbedded method.
//
// SetEmbedded adds a slice of objects under a named key in the embedded map
type EmbedSetter interface {
	SetEmbedded(name string, embedded Embedded)
}

// EmbedSetter is the interface that wraps the basic setEmbedded method.
//
// GetEmbedded returns a slice of embedded resources by name or error
type EmbedGetter interface {
	GetEmbedded(name string) (Embedded, error)
}

// Embeddeer is the interface that wraps the basic setEmbedded and getEmbedded methods.
type Embedder interface {
	EmbedSetter
	EmbedGetter
}

// Hal is used for composition, include it as anonymous field in your structs
type Hal struct {
	Links    map[string]*Link    `json:"_links,omitempty"`
	Embedded map[string]Embedded `json:"_embedded,omitempty"`
}

// SetLink sets a link (self, next, etc). Title argument is optional
func (h *Hal) SetLink(name, href, title string) {
	if h.Links == nil {
		h.Links = make(map[string]*Link, 0)
	}
	h.Links[name] = &Link{Href: href, Title: title}
}

// DeleteLink removes a link named name if it is found
func (h *Hal) DeleteLink(name string) {
	if h.Links != nil {
		delete(h.Links, name)
	}
}

// GetLink returns a link by name or error
func (h *Hal) GetLink(name string) (*Link, error) {
	if h.Links == nil {
		return nil, fmt.Errorf("Link \"%s\" not found", name)
	}
	link, ok := h.Links[name]
	if !ok {
		return nil, fmt.Errorf("Link \"%s\" not found", name)
	}
	return link, nil
}

// SetEmbedded adds a slice of objects under a named key in the embedded map
func (h *Hal) SetEmbedded(name string, embedded Embedded) {
	if h.Embedded == nil {
		h.Embedded = make(map[string]Embedded, 0)
	}
	h.Embedded[name] = embedded
}

// GetEmbedded returns a slice of embedded resources by name or error
func (h *Hal) GetEmbedded(name string) (Embedded, error) {
	if h.Embedded == nil {
		return nil, fmt.Errorf("Embedded \"%s\" not found", name)
	}
	embedded, ok := h.Embedded[name]
	if !ok {
		return nil, fmt.Errorf("Embedded \"%s\" not found", name)
	}
	return embedded, nil
}

// DeleteEmbedded removes an embedded resource named name if it is found
func (h *Hal) DeleteEmbedded(name string) {
	if h.Embedded != nil {
		delete(h.Embedded, name)
	}
}