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Resources
Request handling

Resources#

Often web applications need to build very similar “CRUD” end-points. To help reduce the amount of thought and complexity involved in this, Buffalo supports the concept of a “Resource”.

The github.com/gobuffalo/buffalo#Resource interface allows Buffalo to map common routes and respond to common requests.

Desde 0.14.1
type Resource interface {
	List(Context) error
	Show(Context) error
	Create(Context) error
	Update(Context) error
	Destroy(Context) error
}

The github.com/gobuffalo/buffalo#Resource interface was made smaller in release v0.14.1. The New and Edit methods, which serve the HTML forms to edit the resource, are now optional.

Here’s what the interface looked like before:

type Resource interface {
	List(Context) error
	Show(Context) error
	New(Context) error
	Create(Context) error
	Edit(Context) error
	Update(Context) error
	Destroy(Context) error
}

Using Resources#

After implementing the necessary methods on the github.com/gobuffalo/buffalo#Resource interface, the resource can then be mapped to the application using the github.com/gobuffalo/buffalo#App.Resource method.

// action/users.go
type UsersResource struct{ }

func (u UsersResource) List(c buffalo.Context) error {
  // do work
}

func (u UsersResource) Show(c buffalo.Context) error {
  // do work
}

func (u UsersResource) Create(c buffalo.Context) error {
  // do work
}

func (u UsersResource) Update(c buffalo.Context) error {
  // do work
}

func (u UsersResource) Destroy(c buffalo.Context) error {
  // do work
}

Mapping the Resource in app.go:

// actions/app.go
app.Resource("/users", UsersResource{})

The above code example would be the equivalent of the following:

// actions/app.go
ur := UsersResource{}

app.GET("/users", ur.List)
app.GET("/users/{user_id}", ur.Show)
app.POST("/users", ur.Create)
app.PUT("/users/{user_id}", ur.Update)
app.DELETE("/users/{user_id}", ur.Destroy)

It will produce a routing table that looks similar to:

$ buffalo routes

METHOD | HOST                  | PATH                    | ALIASES | NAME                 | HANDLER
------ | ----                  | ----                    | ------- | ----                 | -------
GET    | http://127.0.0.1:3000 | /users/                 |         | usersPath            | coke/actions.UsersResource.List
POST   | http://127.0.0.1:3000 | /users/                 |         | usersPath            | coke/actions.UsersResource.Create
GET    | http://127.0.0.1:3000 | /users/{user_id}/       |         | userPath             | coke/actions.UsersResource.Show
PUT    | http://127.0.0.1:3000 | /users/{user_id}/       |         | userPath             | coke/actions.UsersResource.Update
DELETE | http://127.0.0.1:3000 | /users/{user_id}/       |         | userPath             | coke/actions.UsersResource.Destroy

Optional Resource Methods#

Desde 0.14.1

In v0.14.1 the github.com/gobuffalo/buffalo#Resource was made smaller with the following methods now being optional:

New(Context) error
Edit(Context) error

When implemented the New and Edit methods will add the following to the routing table:

METHOD | HOST                   | PATH                   | ALIASES | NAME         | HANDLER
------ | ----                   | ----                   | ------- | ----         | -------
GET    | http://127.0.0.1:3000  | /users/new             |         | newUsersPath | coke/actions.UsersResource.New
GET    | http://127.0.0.1:3000  | /users/{user_id}/edit/ |         | editUserPath | coke/actions.UsersResource.Edit

Generating Resources#

The buffalo generate resource command will generate the necessary models, migrations, Go code, and HTML to CRUD the resource.

When running the generator in an API application Buffalo will generate code to meet the github.com/gobuffalo/buffalo#Resource interface.

type Resource interface {
  List(Context) error
  Show(Context) error
  Create(Context) error
  Update(Context) error
  Destroy(Context) error
}

When running the generator in a Web application Buffalo will generate code to the meet the github.com/gobuffalo/buffalo#Resource interface, as well as the optional New and Edit methods.

type Resource interface {
  List(Context) error
  Show(Context) error
  New(Context) error
  Create(Context) error
  Edit(Context) error
  Update(Context) error
  Destroy(Context) error
}

Example Resource Generation#

In this example Buffalo will generate the code needed to CRUD a resource named widget (Go: Widget) that has the following attributes:

Model Attribute Go Type DB type Form Type
title Title string varchar text
description Description nulls.String varchar (nullable) textarea
$ buffalo generate resource widget title description:nulls.Text
actions/app.go
actions/widgets.go
actions/widgets_test.go
package actions

import (
	"net/http"

	"coke/locales"
	"coke/models"
	"coke/public"

	"github.com/gobuffalo/buffalo"
	"github.com/gobuffalo/buffalo-pop/v3/pop/popmw"
	"github.com/gobuffalo/envy"
	csrf "github.com/gobuffalo/mw-csrf"
	forcessl "github.com/gobuffalo/mw-forcessl"
	i18n "github.com/gobuffalo/mw-i18n/v2"
	paramlogger "github.com/gobuffalo/mw-paramlogger"
	"github.com/unrolled/secure"
)

// ENV is used to help switch settings based on where the
// application is being run. Default is "development".
var ENV = envy.Get("GO_ENV", "development")

var (
	app *buffalo.App
	T   *i18n.Translator
)

// App is where all routes and middleware for buffalo
// should be defined. This is the nerve center of your
// application.
//
// Routing, middleware, groups, etc... are declared TOP -> DOWN.
// This means if you add a middleware to `app` *after* declaring a
// group, that group will NOT have that new middleware. The same
// is true of resource declarations as well.
//
// It also means that routes are checked in the order they are declared.
// `ServeFiles` is a CATCH-ALL route, so it should always be
// placed last in the route declarations, as it will prevent routes
// declared after it to never be called.
func App() *buffalo.App {
	if app == nil {
		app = buffalo.New(buffalo.Options{
			Env:         ENV,
			SessionName: "_coke_session",
		})

		// Automatically redirect to SSL
		app.Use(forceSSL())

		// Log request parameters (filters apply).
		app.Use(paramlogger.ParameterLogger)

		// Protect against CSRF attacks. https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)
		// Remove to disable this.
		app.Use(csrf.New)

		// Wraps each request in a transaction.
		//   c.Value("tx").(*pop.Connection)
		// Remove to disable this.
		app.Use(popmw.Transaction(models.DB))
		// Setup and use translations:
		app.Use(translations())

		app.GET("/", HomeHandler)

		app.Resource("/widgets", WidgetsResource{})
		app.ServeFiles("/", http.FS(public.FS())) // serve files from the public directory
	}

	return app
}

// translations will load locale files, set up the translator `actions.T`,
// and will return a middleware to use to load the correct locale for each
// request.
// for more information: https://gobuffalo.io/en/docs/localization
func translations() buffalo.MiddlewareFunc {
	var err error
	if T, err = i18n.New(locales.FS(), "en-US"); err != nil {
		app.Stop(err)
	}
	return T.Middleware()
}

// forceSSL will return a middleware that will redirect an incoming request
// if it is not HTTPS. "http://example.com" => "https://example.com".
// This middleware does **not** enable SSL. for your application. To do that
// we recommend using a proxy: https://gobuffalo.io/en/docs/proxy
// for more information: https://github.com/unrolled/secure/
func forceSSL() buffalo.MiddlewareFunc {
	return forcessl.Middleware(secure.Options{
		SSLRedirect:     ENV == "production",
		SSLProxyHeaders: map[string]string{"X-Forwarded-Proto": "https"},
	})
}

locales/widgets.en-us.yaml
- id: "widget.created.success"
  translation: "Widget was successfully created."
- id: "widget.updated.success"
  translation: "Widget was successfully updated."
- id: "widget.destroyed.success"
  translation: "Widget was successfully destroyed."

migrations/20181005153028_create_widgets.up.fizz
migrations/20181005153028_create_widgets.down.fizz
create_table("widgets") {
	t.Column("id", "uuid", {primary: true})
	t.Column("title", "string", {})
	t.Column("description", "text", {null: true})
	t.Timestamps()
}

models/widget.go
models/widget_test.go
package models

import (
	"encoding/json"
	"time"

	"github.com/gobuffalo/nulls"
	"github.com/gobuffalo/pop/v6"
	"github.com/gobuffalo/validate/v3"
	"github.com/gobuffalo/validate/v3/validators"
	"github.com/gofrs/uuid"
)

// Widget is used by pop to map your widgets database table to your go code.
type Widget struct {
	ID          uuid.UUID    `json:"id" db:"id"`
	Title       string       `json:"title" db:"title"`
	Description nulls.String `json:"description" db:"description"`
	CreatedAt   time.Time    `json:"created_at" db:"created_at"`
	UpdatedAt   time.Time    `json:"updated_at" db:"updated_at"`
}

// String is not required by pop and may be deleted
func (w Widget) String() string {
	jw, _ := json.Marshal(w)
	return string(jw)
}

// Widgets is not required by pop and may be deleted
type Widgets []Widget

// String is not required by pop and may be deleted
func (w Widgets) String() string {
	jw, _ := json.Marshal(w)
	return string(jw)
}

// Validate gets run every time you call a "pop.Validate*" (pop.ValidateAndSave, pop.ValidateAndCreate, pop.ValidateAndUpdate) method.
// This method is not required and may be deleted.
func (w *Widget) Validate(tx *pop.Connection) (*validate.Errors, error) {
	return validate.Validate(
		&validators.StringIsPresent{Field: w.Title, Name: "Title"},
	), nil
}

// ValidateCreate gets run every time you call "pop.ValidateAndCreate" method.
// This method is not required and may be deleted.
func (w *Widget) ValidateCreate(tx *pop.Connection) (*validate.Errors, error) {
	return validate.NewErrors(), nil
}

// ValidateUpdate gets run every time you call "pop.ValidateAndUpdate" method.
// This method is not required and may be deleted.
func (w *Widget) ValidateUpdate(tx *pop.Connection) (*validate.Errors, error) {
	return validate.NewErrors(), nil
}

templates/widgets/_form.plush.html
templates/widgets/edit.plush.html
templates/widgets/index.plush.html
templates/widgets/new.plush.html
templates/widgets/show.plush.html
<%= f.InputTag("Title") %>
<%= f.TextAreaTag("Description", {rows: 10}) %>
<button class="btn btn-success" role="submit">Save</button>

Destroying Resources#

You can remove files generated by this generator by running:

$ buffalo destroy resource users

This command will ask you which files you want to remove, you can either answer each of the questions with y/n or you can pass the -y flag to the command like:

$ buffalo destroy resource users -y

Or in short form:

$ buffalo d r users -y

Nesting Resources#

To simplify creating resource hierarchies, Buffalo supports nesting resources.

type WidgetsResource struct {
	buffalo.Resource
}

type ImagesResource struct {
  buffalo.Resource
}

w := app.Resource("/widgets", WidgetsResource{})
w.Resource("/images", ImagesResource{})

This results in the following routes:

$ buffalo routes

METHOD | HOST                  | PATH                                         | ALIASES | NAME                | HANDLER
------ | ----                  | ----                                         | ------- | ----                | -------
GET    | http://127.0.0.1:3000 | /                                            |         | rootPath            | coke/actions.HomeHandler
GET    | http://127.0.0.1:3000 | /widgets/                                    |         | widgetsPath         | coke/actions.WidgetsResource.List
POST   | http://127.0.0.1:3000 | /widgets/                                    |         | widgetsPath         | coke/actions.WidgetsResource.Create
GET    | http://127.0.0.1:3000 | /widgets/new/                                |         | newWidgetsPath      | coke/actions.WidgetsResource.New
GET    | http://127.0.0.1:3000 | /widgets/{widget_id}/                        |         | widgetPath          | coke/actions.WidgetsResource.Show
PUT    | http://127.0.0.1:3000 | /widgets/{widget_id}/                        |         | widgetPath          | coke/actions.WidgetsResource.Update
DELETE | http://127.0.0.1:3000 | /widgets/{widget_id}/                        |         | widgetPath          | coke/actions.WidgetsResource.Destroy
GET    | http://127.0.0.1:3000 | /widgets/{widget_id}/edit/                   |         | editWidgetPath      | coke/actions.WidgetsResource.Edit
GET    | http://127.0.0.1:3000 | /widgets/{widget_id}/images/                 |         | widgetImagesPath    | coke/actions.ImagesResource.List
POST   | http://127.0.0.1:3000 | /widgets/{widget_id}/images/                 |         | widgetImagesPath    | coke/actions.ImagesResource.Create
GET    | http://127.0.0.1:3000 | /widgets/{widget_id}/images/new/             |         | newWidgetImagesPath | coke/actions.ImagesResource.New
GET    | http://127.0.0.1:3000 | /widgets/{widget_id}/images/{image_id}/      |         | widgetImagePath     | coke/actions.ImagesResource.Show
PUT    | http://127.0.0.1:3000 | /widgets/{widget_id}/images/{image_id}/      |         | widgetImagePath     | coke/actions.ImagesResource.Update
DELETE | http://127.0.0.1:3000 | /widgets/{widget_id}/images/{image_id}/      |         | widgetImagePath     | coke/actions.ImagesResource.Destroy
GET    | http://127.0.0.1:3000 | /widgets/{widget_id}/images/{image_id}/edit/ |         | editWidgetImagePath | coke/actions.ImagesResource.Edit

buffalo.BaseResource#

When a resource is generated it has buffalo.BaseResource embedded into it.

type Widget struct {
  buffalo.BaseResource
}

The buffalo.BaseResource has basic implementations for all of the methods required by buffalo.Resource. These methods all 404.

// Edit default implementation. Returns a 404
func (v BaseResource) Edit(c Context) error {
  return c.Error(http.StatusNotFound, errors.New("resource not implemented"))
}

Video Presentation#

  • Actions - Learn more about Buffalo actions.

Next Steps#

  • Context - Learn more about Buffalo context.