add a new 'overview' MVC example

Former-commit-id: f73cbf6010595c639f6c5b5119e2ec41bc9802a5

_examples/mvc/repository/datamodels/README.md

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+# Data Model Layer

_examples/mvc/repository/datamodels/movie.go

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+// file: datamodels/movie.go
+
+package datamodels
+
+// Movie is our sample data structure.
+// Keep note that the tags for public-use (for our web app)
+// should be kept in other file like "web/viewmodels/movie.go"
+// which could wrap by embedding the datamodels.Movie or
+// declare new fields instead butwe will use this datamodel
+// as the only one Movie model in our application,
+// for the sake of simplicty.
+type Movie struct {
+	ID     int64  `json:"id"`
+	Name   string `json:"name"`
+	Year   int    `json:"year"`
+	Genre  string `json:"genre"`
+	Poster string `json:"poster"`
+}

_examples/mvc/repository/datasource/README.md

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+# Data Source / Data Store Layer

_examples/mvc/repository/datasource/movies.go

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+// file: datasource/movies.go
+
+package datasource
+
+import "github.com/kataras/iris/v12/_examples/mvc/repository/datamodels"
+
+// Movies is our imaginary data source.
+var Movies = map[int64]datamodels.Movie{
+	1: {
+		ID:     1,
+		Name:   "Casablanca",
+		Year:   1942,
+		Genre:  "Romance",
+		Poster: "https://iris-go.com/images/examples/mvc-movies/1.jpg",
+	},
+	2: {
+		ID:     2,
+		Name:   "Gone with the Wind",
+		Year:   1939,
+		Genre:  "Romance",
+		Poster: "https://iris-go.com/images/examples/mvc-movies/2.jpg",
+	},
+	3: {
+		ID:     3,
+		Name:   "Citizen Kane",
+		Year:   1941,
+		Genre:  "Mystery",
+		Poster: "https://iris-go.com/images/examples/mvc-movies/3.jpg",
+	},
+	4: {
+		ID:     4,
+		Name:   "The Wizard of Oz",
+		Year:   1939,
+		Genre:  "Fantasy",
+		Poster: "https://iris-go.com/images/examples/mvc-movies/4.jpg",
+	},
+	5: {
+		ID:     5,
+		Name:   "North by Northwest",
+		Year:   1959,
+		Genre:  "Thriller",
+		Poster: "https://iris-go.com/images/examples/mvc-movies/5.jpg",
+	},
+}

_examples/mvc/repository/main.go

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+// file: main.go
+
+package main
+
+import (
+	"github.com/kataras/iris/v12/_examples/mvc/repository/datasource"
+	"github.com/kataras/iris/v12/_examples/mvc/repository/repositories"
+	"github.com/kataras/iris/v12/_examples/mvc/repository/services"
+	"github.com/kataras/iris/v12/_examples/mvc/repository/web/controllers"
+	"github.com/kataras/iris/v12/_examples/mvc/repository/web/middleware"
+
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/mvc"
+)
+
+func main() {
+	app := iris.New()
+	app.Logger().SetLevel("debug")
+
+	// Load the template files.
+	app.RegisterView(iris.HTML("./web/views", ".html"))
+
+	// Serve our controllers.
+	mvc.New(app.Party("/hello")).Handle(new(controllers.HelloController))
+	// You can also split the code you write to configure an mvc.Application
+	// using the `mvc.Configure` method, as shown below.
+	mvc.Configure(app.Party("/movies"), movies)
+
+	// http://localhost:8080/hello
+	// http://localhost:8080/hello/iris
+	// http://localhost:8080/movies
+	// http://localhost:8080/movies/1
+	app.Listen(":8080", iris.WithOptimizations)
+}
+
+// note the mvc.Application, it's not iris.Application.
+func movies(app *mvc.Application) {
+	// Add the basic authentication(admin:password) middleware
+	// for the /movies based requests.
+	app.Router.Use(middleware.BasicAuth)
+
+	// Create our movie repository with some (memory) data from the datasource.
+	repo := repositories.NewMovieRepository(datasource.Movies)
+	// Create our movie service, we will bind it to the movie app's dependencies.
+	movieService := services.NewMovieService(repo)
+	app.Register(movieService)
+
+	// serve our movies controller.
+	// Note that you can serve more than one controller
+	// you can also create child mvc apps using the `movies.Party(relativePath)` or `movies.Clone(app.Party(...))`
+	// if you want.
+	app.Handle(new(controllers.MovieController))
+}

_examples/mvc/repository/models/README.md

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+# Domain Models
+
+There should be the domain/business-level models.
+
+Example:
+
+```go
+import "github.com/kataras/iris/v12/_examples/mvc/repository/datamodels"
+
+type Movie struct {
+    datamodels.Movie
+}
+
+func (m Movie) Validate() (Movie, error) {
+    /* do some checks and return an error if that Movie is not valid */
+}
+```
+
+However, we will use the "datamodels" as the only one models package because
+Movie structure we don't need any extra functionality or validation inside it.

_examples/mvc/repository/repositories/README.md

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+# Repositories
+
+The package which has direct access to the "datasource" and can manipulate data directly.

_examples/mvc/repository/repositories/movie_repository.go

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+// file: repositories/movie_repository.go
+
+package repositories
+
+import (
+	"errors"
+	"sync"
+
+	"github.com/kataras/iris/v12/_examples/mvc/repository/datamodels"
+)
+
+// Query represents the visitor and action queries.
+type Query func(datamodels.Movie) bool
+
+// MovieRepository handles the basic operations of a movie entity/model.
+// It's an interface in order to be testable, i.e a memory movie repository or
+// a connected to an sql database.
+type MovieRepository interface {
+	Exec(query Query, action Query, limit int, mode int) (ok bool)
+
+	Select(query Query) (movie datamodels.Movie, found bool)
+	SelectMany(query Query, limit int) (results []datamodels.Movie)
+
+	InsertOrUpdate(movie datamodels.Movie) (updatedMovie datamodels.Movie, err error)
+	Delete(query Query, limit int) (deleted bool)
+}
+
+// NewMovieRepository returns a new movie memory-based repository,
+// the one and only repository type in our example.
+func NewMovieRepository(source map[int64]datamodels.Movie) MovieRepository {
+	return &movieMemoryRepository{source: source}
+}
+
+// movieMemoryRepository is a "MovieRepository"
+// which manages the movies using the memory data source (map).
+type movieMemoryRepository struct {
+	source map[int64]datamodels.Movie
+	mu     sync.RWMutex
+}
+
+const (
+	// ReadOnlyMode will RLock(read) the data .
+	ReadOnlyMode = iota
+	// ReadWriteMode will Lock(read/write) the data.
+	ReadWriteMode
+)
+
+func (r *movieMemoryRepository) Exec(query Query, action Query, actionLimit int, mode int) (ok bool) {
+	loops := 0
+
+	if mode == ReadOnlyMode {
+		r.mu.RLock()
+		defer r.mu.RUnlock()
+	} else {
+		r.mu.Lock()
+		defer r.mu.Unlock()
+	}
+
+	for _, movie := range r.source {
+		ok = query(movie)
+		if ok {
+			if action(movie) {
+				loops++
+				if actionLimit >= loops {
+					break // break
+				}
+			}
+		}
+	}
+
+	return
+}
+
+// Select receives a query function
+// which is fired for every single movie model inside
+// our imaginary data source.
+// When that function returns true then it stops the iteration.
+//
+// It returns the query's return last known "found" value
+// and the last known movie model
+// to help callers to reduce the LOC.
+//
+// It's actually a simple but very clever prototype function
+// I'm using everywhere since I firstly think of it,
+// hope you'll find it very useful as well.
+func (r *movieMemoryRepository) Select(query Query) (movie datamodels.Movie, found bool) {
+	found = r.Exec(query, func(m datamodels.Movie) bool {
+		movie = m
+		return true
+	}, 1, ReadOnlyMode)
+
+	// set an empty datamodels.Movie if not found at all.
+	if !found {
+		movie = datamodels.Movie{}
+	}
+
+	return
+}
+
+// SelectMany same as Select but returns one or more datamodels.Movie as a slice.
+// If limit <=0 then it returns everything.
+func (r *movieMemoryRepository) SelectMany(query Query, limit int) (results []datamodels.Movie) {
+	r.Exec(query, func(m datamodels.Movie) bool {
+		results = append(results, m)
+		return true
+	}, limit, ReadOnlyMode)
+
+	return
+}
+
+// InsertOrUpdate adds or updates a movie to the (memory) storage.
+//
+// Returns the new movie and an error if any.
+func (r *movieMemoryRepository) InsertOrUpdate(movie datamodels.Movie) (datamodels.Movie, error) {
+	id := movie.ID
+
+	if id == 0 { // Create new action
+		var lastID int64
+		// find the biggest ID in order to not have duplications
+		// in productions apps you can use a third-party
+		// library to generate a UUID as string.
+		r.mu.RLock()
+		for _, item := range r.source {
+			if item.ID > lastID {
+				lastID = item.ID
+			}
+		}
+		r.mu.RUnlock()
+
+		id = lastID + 1
+		movie.ID = id
+
+		// map-specific thing
+		r.mu.Lock()
+		r.source[id] = movie
+		r.mu.Unlock()
+
+		return movie, nil
+	}
+
+	// Update action based on the movie.ID,
+	// here we will allow updating the poster and genre if not empty.
+	// Alternatively we could do pure replace instead:
+	// r.source[id] = movie
+	// and comment the code below;
+	current, exists := r.Select(func(m datamodels.Movie) bool {
+		return m.ID == id
+	})
+
+	if !exists { // ID is not a real one, return an error.
+		return datamodels.Movie{}, errors.New("failed to update a nonexistent movie")
+	}
+
+	// or comment these and r.source[id] = m for pure replace
+	if movie.Poster != "" {
+		current.Poster = movie.Poster
+	}
+
+	if movie.Genre != "" {
+		current.Genre = movie.Genre
+	}
+
+	// map-specific thing
+	r.mu.Lock()
+	r.source[id] = current
+	r.mu.Unlock()
+
+	return movie, nil
+}
+
+func (r *movieMemoryRepository) Delete(query Query, limit int) bool {
+	return r.Exec(query, func(m datamodels.Movie) bool {
+		delete(r.source, m.ID)
+		return true
+	}, limit, ReadWriteMode)
+}

_examples/mvc/repository/services/README.md

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+# Service Layer
+
+The package which has access to call functions from the "repositories" and "models" ("datamodels" only in that simple example). It should contain the domain logic.

_examples/mvc/repository/services/movie_service.go

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+// file: services/movie_service.go
+
+package services
+
+import (
+	"github.com/kataras/iris/v12/_examples/mvc/repository/datamodels"
+	"github.com/kataras/iris/v12/_examples/mvc/repository/repositories"
+)
+
+// MovieService handles some of the CRUID operations of the movie datamodel.
+// It depends on a movie repository for its actions.
+// It's here to decouple the data source from the higher level compoments.
+// As a result a different repository type can be used with the same logic without any aditional changes.
+// It's an interface and it's used as interface everywhere
+// because we may need to change or try an experimental different domain logic at the future.
+type MovieService interface {
+	GetAll() []datamodels.Movie
+	GetByID(id int64) (datamodels.Movie, bool)
+	DeleteByID(id int64) bool
+	UpdatePosterAndGenreByID(id int64, poster string, genre string) (datamodels.Movie, error)
+}
+
+// NewMovieService returns the default movie service.
+func NewMovieService(repo repositories.MovieRepository) MovieService {
+	return &movieService{
+		repo: repo,
+	}
+}
+
+type movieService struct {
+	repo repositories.MovieRepository
+}
+
+// GetAll returns all movies.
+func (s *movieService) GetAll() []datamodels.Movie {
+	return s.repo.SelectMany(func(_ datamodels.Movie) bool {
+		return true
+	}, -1)
+}
+
+// GetByID returns a movie based on its id.
+func (s *movieService) GetByID(id int64) (datamodels.Movie, bool) {
+	return s.repo.Select(func(m datamodels.Movie) bool {
+		return m.ID == id
+	})
+}
+
+// UpdatePosterAndGenreByID updates a movie's poster and genre.
+func (s *movieService) UpdatePosterAndGenreByID(id int64, poster string, genre string) (datamodels.Movie, error) {
+	// update the movie and return it.
+	return s.repo.InsertOrUpdate(datamodels.Movie{
+		ID:     id,
+		Poster: poster,
+		Genre:  genre,
+	})
+}
+
+// DeleteByID deletes a movie by its id.
+//
+// Returns true if deleted otherwise false.
+func (s *movieService) DeleteByID(id int64) bool {
+	return s.repo.Delete(func(m datamodels.Movie) bool {
+		return m.ID == id
+	}, 1)
+}

_examples/mvc/repository/web/controllers/hello_controller.go

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+// file: web/controllers/hello_controller.go
+
+package controllers
+
+import (
+	"errors"
+
+	"github.com/kataras/iris/v12/mvc"
+)
+
+// HelloController is our sample controller
+// it handles GET: /hello and GET: /hello/{name}
+type HelloController struct{}
+
+var helloView = mvc.View{
+	Name: "hello/index.html",
+	Data: map[string]interface{}{
+		"Title":     "Hello Page",
+		"MyMessage": "Welcome to my awesome website",
+	},
+}
+
+// Get will return a predefined view with bind data.
+//
+// `mvc.Result` is just an interface with a `Dispatch` function.
+// `mvc.Response` and `mvc.View` are the builtin result type dispatchers
+// you can even create custom response dispatchers by
+// implementing the `github.com/kataras/iris/hero#Result` interface.
+func (c *HelloController) Get() mvc.Result {
+	return helloView
+}
+
+// you can define a standard error in order to re-use anywhere in your app.
+var errBadName = errors.New("bad name")
+
+// you can just return it as error or even better
+// wrap this error with an mvc.Response to make it an mvc.Result compatible type.
+var badName = mvc.Response{Err: errBadName, Code: 400}
+
+// GetBy returns a "Hello {name}" response.
+// Demos:
+// curl -i http://localhost:8080/hello/iris
+// curl -i http://localhost:8080/hello/anything
+func (c *HelloController) GetBy(name string) mvc.Result {
+	if name != "iris" {
+		return badName
+		// or
+		// GetBy(name string) (mvc.Result, error) {
+		//	return nil, errBadName
+		// }
+	}
+
+	// return mvc.Response{Text: "Hello " + name} OR:
+	return mvc.View{
+		Name: "hello/name.html",
+		Data: name,
+	}
+}

_examples/mvc/repository/web/controllers/movie_controller.go

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+// file: web/controllers/movie_controller.go
+
+package controllers
+
+import (
+	"errors"
+
+	"github.com/kataras/iris/v12/_examples/mvc/repository/datamodels"
+	"github.com/kataras/iris/v12/_examples/mvc/repository/services"
+
+	"github.com/kataras/iris/v12"
+)
+
+// MovieController is our /movies controller.
+type MovieController struct {
+	// Our MovieService, it's an interface which
+	// is binded from the main application.
+	Service services.MovieService
+}
+
+// Get returns list of the movies.
+// Demo:
+// curl -i http://localhost:8080/movies
+//
+// The correct way if you have sensitive data:
+// func (c *MovieController) Get() (results []viewmodels.Movie) {
+// 	data := c.Service.GetAll()
+//
+// 	for _, movie := range data {
+// 		results = append(results, viewmodels.Movie{movie})
+// 	}
+// 	return
+// }
+// otherwise just return the datamodels.
+func (c *MovieController) Get() (results []datamodels.Movie) {
+	return c.Service.GetAll()
+}
+
+// GetBy returns a movie.
+// Demo:
+// curl -i http://localhost:8080/movies/1
+func (c *MovieController) GetBy(id int64) (movie datamodels.Movie, found bool) {
+	return c.Service.GetByID(id) // it will throw 404 if not found.
+}
+
+// PutBy updates a movie.
+// Demo:
+// curl -i -X PUT -F "genre=Thriller" -F "poster=@/Users/kataras/Downloads/out.gif" http://localhost:8080/movies/1
+func (c *MovieController) PutBy(ctx iris.Context, id int64) (datamodels.Movie, error) {
+	// get the request data for poster and genre
+	file, info, err := ctx.FormFile("poster")
+	if err != nil {
+		return datamodels.Movie{}, errors.New("failed due form file 'poster' missing")
+	}
+	// we don't need the file so close it now.
+	file.Close()
+
+	// imagine that is the url of the uploaded file...
+	poster := info.Filename
+	genre := ctx.FormValue("genre")
+
+	return c.Service.UpdatePosterAndGenreByID(id, poster, genre)
+}
+
+// DeleteBy deletes a movie.
+// Demo:
+// curl -i -X DELETE -u admin:password http://localhost:8080/movies/1
+func (c *MovieController) DeleteBy(id int64) interface{} {
+	wasDel := c.Service.DeleteByID(id)
+	if wasDel {
+		// return the deleted movie's ID
+		return iris.Map{"deleted": id}
+	}
+	// right here we can see that a method function can return any of those two types(map or int),
+	// we don't have to specify the return type to a specific type.
+	return iris.StatusBadRequest
+}

_examples/mvc/repository/web/middleware/basicauth.go

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+// file: web/middleware/basicauth.go
+
+package middleware
+
+import "github.com/kataras/iris/v12/middleware/basicauth"
+
+// BasicAuth middleware sample.
+var BasicAuth = basicauth.New(basicauth.Config{
+	Users: map[string]string{
+		"admin": "password",
+	},
+})

_examples/mvc/repository/web/viewmodels/README.md

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+# View Models
+
+There should be the view models, the structure that the client will be able to see.
+
+Example:
+
+```go
+import (
+    "github.com/kataras/iris/v12/_examples/mvc/repository/datamodels"
+
+    "github.com/kataras/iris/v12"
+    "github.com/kataras/iris/v12/context"
+)
+
+type Movie struct {
+    datamodels.Movie
+}
+
+func (m Movie) IsValid() bool {
+    /* do some checks and return true if it's valid... */
+    return m.ID > 0
+}
+```
+
+Iris is able to convert any custom data Structure into an HTTP Response Dispatcher,
+so theoretically, something like the following is permitted if it's really necessary;
+
+```go
+// Dispatch completes the `kataras/iris/mvc#Result` interface.
+// Sends a `Movie` as a controlled http response.
+// If its ID is zero or less then it returns a 404 not found error
+// else it returns its json representation,
+// (just like the controller's functions do for custom types by default).
+//
+// Don't overdo it, the application's logic should not be here.
+// It's just one more step of validation before the response,
+// simple checks can be added here.
+//
+// It's just a showcase,
+// imagine the potentials this feature gives when designing a bigger application.
+//
+// This is called where the return value from a controller's method functions
+// is type of `Movie`.
+// For example the `controllers/movie_controller.go#GetBy`.
+func (m Movie) Dispatch(ctx iris.Context) {
+    if !m.IsValid() {
+        ctx.NotFound()
+        return
+    }
+    ctx.JSON(m, context.JSON{Indent: " "})
+}
+```
+
+However, we will use the "datamodels" as the only one models package because
+Movie structure doesn't contain any sensitive data, clients are able to see all of its fields
+and we don't need any extra functionality or validation inside it.

_examples/mvc/repository/web/views/hello/index.html

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+<!-- file: web/views/hello/index.html -->
+<html>
+
+<head>
+    <title>{{.Title}} - My App</title>
+</head>
+
+<body>
+    <p>{{.MyMessage}}</p>
+</body>
+
+</html>

_examples/mvc/repository/web/views/hello/name.html

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+<!-- file: web/views/hello/name.html -->
+<html>
+
+<head>
+    <title>{{.}}' Portfolio - My App</title>
+</head>
+
+<body>
+    <h1>Hello {{.}}</h1>
+</body>
+
+</html>