諾羅不是病: 2018

2018年6月4日星期一

ASP.NET MVC 5 － Adding Validation

᳓前言

本篇文章將"Adding Validation"整理而成。

᳓重點整理

在Model類別中加入驗證邏輯，如此一來，在這個應用程式中對於該Model的所有新增、修改都會依照該邏輯進行驗證。
ASP.NET MVC的其中一個核心設計概念為DRY(Don't Repeat Yourself)，意思是只需要指定功能或行為一次之後，在應用程式中有使用到的各部分就能夠體現出來。好處是能夠減少需要撰寫的程式碼，而且可以有效降低錯誤發生並方便維護。

᳓實作1. 修改Models/Movie.cs
首先要確認目前資料表的欄位，之後才能做比較。

開啟伺服器管理員->展開資料連接->展開Movies.mdf->右鍵dbo.Movies->選擇開啟資料表定義

尚未修改的dbo.Movies

修改Movie.cs，為各個欄位新增驗證邏輯。

	using System;
	using System.Collections.Generic;
	using System.ComponentModel.DataAnnotations; // Display
	using System.Data.Entity; // DbContext
	using System.Linq;
	using System.Web;

	namespace WebApplication1.Models
	{
	public class Movie
	{
	public int ID { get; set; }

	[StringLength(60, MinimumLength = 3)]
	public string Title { get; set; }

	[Display(Name = "Rease Date")]
	[DataType(DataType.Date)]
	[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
	//[DisplayFormat(DataFormatString = "0:d", ApplyFormatInEditMode = true)]
	public DateTime ReleaseDate { get; set; }

	[RegularExpression(@"^[A-Z]=[a-zA-Z'\s]*$")]
	[Required]
	[StringLength(30)]
	public string Genre { get; set; }

	[Range(1, 100)]
	[DataType(DataType.Currency)]
	public decimal Price { get; set; }

	[RegularExpression(@"^[A-Z]=[a-zA-Z'\s]*$")]
	[StringLength(5)]
	public string Rating { get; set; }
	}

	public class MovieDBContext : DbContext
	{
	public DbSet<Movie> Movies { get; set; }
	}
	}

view raw Movie.cs hosted with ❤ by GitHub

在套件管理器主控台輸入Add-Midgration AddDataAnnotations，便會自動產生以下程式碼。

	namespace WebApplication1.Migrations
	{
	using System;
	using System.Data.Entity.Migrations;

	public partial class AddDataAnnotations : DbMigration
	{
	public override void Up()
	{
	AlterColumn("dbo.Movies", "Title", c => c.String(maxLength: 60));
	AlterColumn("dbo.Movies", "Genre", c => c.String(nullable: false, maxLength: 30));
	AlterColumn("dbo.Movies", "Rating", c => c.String(maxLength: 5));
	}

	public override void Down()
	{
	AlterColumn("dbo.Movies", "Rating", c => c.String());
	AlterColumn("dbo.Movies", "Genre", c => c.String());
	AlterColumn("dbo.Movies", "Title", c => c.String());
	}
	}
	}

view raw 201806041238259_AddDataAnnotations.cs hosted with ❤ by GitHub

在套件管理器主控台輸入Update-database，執行完畢後再次查看資料表定義會發現已經變更完成。如此一來，當應用程式在變更資料表資料(呼叫SaveChanges方法)時，會優先判斷資料是否符合驗證邏輯，若是不符(比如必填欄位沒有資料)，便會拋出DbEntityValidationException的例外狀況，防止資料庫被存入不好的資料，增加應用程式的強健性。

修改後的dbo.Movies(StringLength：設定字串長度、Display：設定欄位顯示名稱、DataType：設定提示View如何顯示特定的資料、DisplayFormat：指定資料顯示的格式、Required：設定是否為必填項目、Range：設定值域、RegularExpression：設定輸入規則，可防止輸入空格、數字、特殊符號等)

2018年4月3日星期二

ASP.NET MVC 5 － Adding a New Field

᳓前言

本篇文章將"Adding a New Field"整理而成。

᳓重點整理

在完全沒有資料庫檔案的狀況下，透過Code First建立資料庫及資料表。
在已經透過Code First建立的資料庫中，進行資料表的修改。

᳓實作1. 開啟Tools->NuGet Package Manager->Package Manager Console
記得先刪除在之前的練習中自動建立的App_Data/*.mdf檔案後再進行下列的練習。

᳓實作2. 啟用Migrations-在Package Manager Console輸入指令

1. 輸入"Enable-Migrations -ContextTypeName {WebApplication1}.Models.MovieDBContext"->Enter

2. 指令執行完畢後，會在專案中自動建立Migrations資料夾，且在該資料夾中新增Configuration.cs檔案

᳓實作3. 新增Migration-修改Migrations/Configuration.cs、在Package Manager Console輸入指令
修改完Congiguration.cs之後，一定要先重建專案，否則指令會執行失敗。當"add-migration Initial"指令執行完畢後，會自動產生所變更內容的{201804021004386}_Initial.cs檔案。需要注意的是，每次進行Code First Migrations (也就是輸入下一步的update-database指令)都會執行Seed()方法中的程式碼。

	namespace WebApplication1.Migrations
	{
	using System;
	using System.Data.Entity;
	using System.Data.Entity.Migrations;
	using System.Linq;
	using WebApplication1.Models; // Movie

	internal sealed class Configuration : DbMigrationsConfiguration<WebApplication1.Models.MovieDBContext>
	{
	public Configuration()
	{
	AutomaticMigrationsEnabled = false;
	}

	protected override void Seed(WebApplication1.Models.MovieDBContext context)
	{
	context.Movies.AddOrUpdate(i => i.Title,
	new Movie
	{
	Title = "When Harry Met Sally",
	ReleaseDate = DateTime.Parse("1989-1-11"),
	Genre = "Romantic Comedy",
	Price = 7.99M
	},
	new Movie
	{
	Title = "Ghostbusters ",
	ReleaseDate = DateTime.Parse("1984-3-13"),
	Genre = "Comedy",
	Price = 8.99M
	},
	new Movie
	{
	Title = "Ghostbusters 2",
	ReleaseDate = DateTime.Parse("1986-2-23"),
	Genre = "Comedy",
	Price = 9.99M
	},
	new Movie
	{
	Title = "Rio Bravo",
	ReleaseDate = DateTime.Parse("1959-4-15"),
	Genre = "Western",
	Price = 3.99M
	}
	);
	}
	}
	}

view raw Configuration.cs hosted with ❤ by GitHub

1. 輸入"add-migration Initial"->Enter

	namespace WebApplication1.Migrations
	{
	using System;
	using System.Data.Entity.Migrations;

	public partial class Initial : DbMigration
	{
	public override void Up()
	{
	CreateTable(
	"dbo.Movies",
	c => new
	{
	ID = c.Int(nullable: false, identity: true),
	Title = c.String(),
	ReleaseDate = c.DateTime(nullable: false),
	Genre = c.String(),
	Price = c.Decimal(nullable: false, precision: 18, scale: 2),
	})
	.PrimaryKey(t => t.ID);

	}

	public override void Down()
	{
	DropTable("dbo.Movies");
	}
	}
	}

view raw 201804021004386_Initial.cs hosted with ❤ by GitHub

᳓實作4. 進行Code First Migrations-在Package Manager Console輸入指令
當"update-database"指令執行完畢，便已完成資料庫、資料表的建立，可開啟瀏覽器查看。

1. 輸入"update-database"->Enter

2. 網址列輸入"http://{localhost:port}/Movies/Index"

᳓實作5. 新增Rating新欄位-修改Models/Movie.cs、Controllers/MoviesController.cs、Views/Movies/Index.cshtml、Views/Movies/Create.cshtml、

接著要在Movie.cs新增一個Rating欄位，因此MoviesController.cs的Create Action需要增加Bind的欄位、Index.cshtml及Create.cshtml需要增加輸入欄位，而其他頁面，像是Edit.cshtml、Details.cshtml、Delete.cshtml也需要修改，但在這裡省略說明。值得注意的是，修改完畢後可以成功重建專案，但在瀏覽器瀏覽時會出現下圖的錯誤訊息，那是因為Model已經修改，但資料表還沒有更新，所以會以錯誤訊息提示必須更新資料表。

	using System;
	using System.Collections.Generic;
	using System.ComponentModel.DataAnnotations; // Display
	using System.Data.Entity; // DbContext
	using System.Linq;
	using System.Web;

	namespace WebApplication1.Models
	{
	public class Movie
	{
	public int ID { get; set; }
	public string Title { get; set; }

	[Display(Name = "Rease Date")]
	[DataType(DataType.Date)]
	[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
	//[DisplayFormat(DataFormatString = "0:d", ApplyFormatInEditMode = true)]
	public DateTime ReleaseDate { get; set; }
	public string Genre { get; set; }
	public decimal Price { get; set; }
	public string Rating { get; set; }
	}

	public class MovieDBContext : DbContext
	{
	public DbSet<Movie> Movies { get; set; }
	}
	}

view raw Movie.cs hosted with ❤ by GitHub

	using System;
	using System.Collections.Generic;
	using System.Data;
	using System.Data.Entity;
	using System.Linq;
	using System.Net;
	using System.Web;
	using System.Web.Mvc;
	using WebApplication1.Models;

	namespace WebApplication1.Controllers
	{
	public class MoviesController : Controller
	{
	private MovieDBContext db = new MovieDBContext();

	// GET: Movies/Index?searchString={text}
	public ActionResult Index(string movieGenre, string searchString)
	{
	var GenreLst = new List<string>();
	var GenreQry = (from d in db.Movies
	orderby d.Genre
	select d.Genre);
	GenreLst.AddRange(GenreQry.Distinct());
	ViewBag.movieGenre = new SelectList(GenreLst, "愛情片");

	var movies = (from m in db.Movies
	select m);
	if (!String.IsNullOrEmpty(movieGenre))
	{
	movies = movies.Where(s => s.Genre == movieGenre);
	}
	if(!String.IsNullOrEmpty(searchString))
	{
	movies = movies.Where(s => s.Title.Contains(searchString));
	}
	return View(movies);
	}

	// GET: Movies/Details/5
	public ActionResult Details(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// GET: Movies/Create
	public ActionResult Create()
	{
	return View();
	}

	// POST: Movies/Create
	// To protect from overposting attacks, please enable the specific properties you want to bind to, for
	// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
	[HttpPost]
	[ValidateAntiForgeryToken]
	public ActionResult Create([Bind(Include = "ID,Title,ReleaseDate,Genre,Price,Rating")] Movie movie)
	{
	if (ModelState.IsValid)
	{
	db.Movies.Add(movie);
	db.SaveChanges();
	return RedirectToAction("Index");
	}

	return View(movie);
	}

	// GET: Movies/Edit/5
	public ActionResult Edit(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// POST: Movies/Edit/5
	// To protect from overposting attacks, please enable the specific properties you want to bind to, for
	// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
	[HttpPost]
	[ValidateAntiForgeryToken]
	public ActionResult Edit([Bind(Include = "ID,Title,ReleaseDate,Genre,Price")] Movie movie)
	{
	if (ModelState.IsValid)
	{
	db.Entry(movie).State = EntityState.Modified;
	db.SaveChanges();
	return RedirectToAction("Index");
	}
	return View(movie);
	}

	// GET: Movies/Delete/5
	public ActionResult Delete(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// POST: Movies/Delete/5
	[HttpPost, ActionName("Delete")]
	[ValidateAntiForgeryToken]
	public ActionResult DeleteConfirmed(int id)
	{
	Movie movie = db.Movies.Find(id);
	db.Movies.Remove(movie);
	db.SaveChanges();
	return RedirectToAction("Index");
	}

	protected override void Dispose(bool disposing)
	{
	if (disposing)
	{
	db.Dispose();
	}
	base.Dispose(disposing);
	}
	}
	}

view raw MoviesController.cs hosted with ❤ by GitHub

	@model IEnumerable<WebApplication1.Models.Movie>

	@{
	ViewBag.Title = "Index";
	}

	<h2>Index</h2>

	<p>
	@Html.ActionLink("Create New", "Create")
	@using (Html.BeginForm("Index", "Movies", FormMethod.Get))
	{
	<p>
	類型：@Html.DropDownList("movieGenre", "全部")
	標題：@Html.TextBox("searchString")<br />
	<input type="submit" value="搜尋" />
	</p>
	}
	</p>
	<table class="table">
	<tr>
	<th>
	@Html.DisplayNameFor(model => model.Title)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.ReleaseDate)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Genre)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Price)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Rating)
	</th>
	<th></th>
	</tr>

	@foreach (var item in Model) {
	<tr>
	<td>
	@Html.DisplayFor(modelItem => item.Title)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.ReleaseDate)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Genre)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Price)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Rating)
	</td>
	<td>
	@Html.ActionLink("Edit", "Edit", new { id=item.ID }) \|
	@Html.ActionLink("Details", "Details", new { id=item.ID }) \|
	@Html.ActionLink("Delete", "Delete", new { id=item.ID })
	</td>
	</tr>
	}

	</table>

view raw Index.cshtml hosted with ❤ by GitHub

	@model WebApplication1.Models.Movie

	@{
	ViewBag.Title = "Create";
	}

	<h2>Create</h2>

	@using (Html.BeginForm())
	{
	@Html.AntiForgeryToken()

	<div class="form-horizontal">
	<h4>Movie</h4>
	<hr />
	@Html.ValidationSummary(true, "", new { @class = "text-danger" })
	<div class="form-group">
	@Html.LabelFor(model => model.Title, htmlAttributes: new { @class = "control-label col-md-2" })
	<div class="col-md-10">
	@Html.EditorFor(model => model.Title, new { htmlAttributes = new { @class = "form-control" } })
	@Html.ValidationMessageFor(model => model.Title, "", new { @class = "text-danger" })
	</div>
	</div>

	<div class="form-group">
	@Html.LabelFor(model => model.ReleaseDate, htmlAttributes: new { @class = "control-label col-md-2" })
	<div class="col-md-10">
	@Html.EditorFor(model => model.ReleaseDate, new { htmlAttributes = new { @class = "form-control" } })
	@Html.ValidationMessageFor(model => model.ReleaseDate, "", new { @class = "text-danger" })
	</div>
	</div>

	<div class="form-group">
	@Html.LabelFor(model => model.Genre, htmlAttributes: new { @class = "control-label col-md-2" })
	<div class="col-md-10">
	@Html.EditorFor(model => model.Genre, new { htmlAttributes = new { @class = "form-control" } })
	@Html.ValidationMessageFor(model => model.Genre, "", new { @class = "text-danger" })
	</div>
	</div>

	<div class="form-group">
	@Html.LabelFor(model => model.Price, htmlAttributes: new { @class = "control-label col-md-2" })
	<div class="col-md-10">
	@Html.EditorFor(model => model.Price, new { htmlAttributes = new { @class = "form-control" } })
	@Html.ValidationMessageFor(model => model.Price, "", new { @class = "text-danger" })
	</div>
	</div>

	<div class="form-group">
	@Html.LabelFor(model => model.Rating, htmlAttributes: new { @class = "control-label col-md-2" })
	<div class="col-md-10">
	@Html.EditorFor(model => model.Rating, new { htmlAttributes = new { @class = "form-control" } })
	@Html.ValidationMessageFor(model => model.Rating, "", new { @class = "text-danger" })
	</div>
	</div>

	<div class="form-group">
	<div class="col-md-offset-2 col-md-10">
	<input type="submit" value="Create" class="btn btn-default" />
	</div>
	</div>
	</div>
	}

	<div>
	@Html.ActionLink("Back to List", "Index")
	</div>

view raw Create.cshtml hosted with ❤ by GitHub

1. 網址列輸入"http://{localhost:port}/Movies/Index"

᳓實作6. 進行Code First Migrations-修改Migrations/Configuration.cs、在Package Manager Console輸入指令 為了使Model與資料表的內容一致，需要再次進行Code First Migrations，而每次進行Code First Migrations時都會重新執行一次Configuration.cs的Seed()，所以若是修改Configuration.cs便能將Rating欄位預設值輸入資料表中。值得注意的是，若之後只是修改預設值，並沒有更改欄位的話，可以直接執行"update-database"指令進行預設值的更新，不需要執行"add-migration"指令。

	namespace WebApplication1.Migrations
	{
	using System;
	using System.Data.Entity;
	using System.Data.Entity.Migrations;
	using System.Linq;
	using WebApplication1.Models; // Movie

	internal sealed class Configuration : DbMigrationsConfiguration<WebApplication1.Models.MovieDBContext>
	{
	public Configuration()
	{
	AutomaticMigrationsEnabled = false;
	}

	protected override void Seed(WebApplication1.Models.MovieDBContext context)
	{
	context.Movies.AddOrUpdate(i => i.Title,
	new Movie
	{
	Title = "When Harry Met Sally",
	ReleaseDate = DateTime.Parse("1989-1-11"),
	Genre = "Romantic Comedy",
	Price = 7.99M,
	Rating = "PG"
	},
	new Movie
	{
	Title = "Ghostbusters ",
	ReleaseDate = DateTime.Parse("1984-3-13"),
	Genre = "Comedy",
	Price = 8.99M,
	Rating = "PG"
	},
	new Movie
	{
	Title = "Ghostbusters 2",
	ReleaseDate = DateTime.Parse("1986-2-23"),
	Genre = "Comedy",
	Price = 9.99M,
	Rating = "PG"
	},
	new Movie
	{
	Title = "Rio Bravo",
	ReleaseDate = DateTime.Parse("1959-4-15"),
	Genre = "Western",
	Price = 3.99M,
	Rating = "PG"
	}
	);
	}
	}
	}

view raw Configuration.cs hosted with ❤ by GitHub

1. 輸入"add-migration Rating"->Enter

2. 輸入"update-database"->Enter

3. 網址列輸入"http://{localhost:port}/Movies/Index"可以看到Rating欄位已經輸入預設值"PG"

2018年3月26日星期一

ASP.NET MVC 5 － Adding a Search

᳓前言

本篇文章將"Adding a Search Method and Search View"整理而成。

᳓重點整理

可直接在URL輸入參數便可作為字串進行標題的搜尋。
在View加入TextBox，可輸入文字並進行標題的搜尋。
在View加入DropDownList，可選擇類型並進行類型的搜尋。

᳓實作1. 修改Controllers/MoviesController.cs
在Index Action新增searchString參數(當然也可以修改為直接利用URL Route的方式搜尋，請參考"ASP.NET MVC 5 － Adding a Controller")，並加入LINQ query程式碼。值得注意的是，LINQ query在初被定義時還沒執行，要等到Index Action回傳結果至View時才會執行。

	using System;
	using System.Collections.Generic;
	using System.Data;
	using System.Data.Entity;
	using System.Linq;
	using System.Net;
	using System.Web;
	using System.Web.Mvc;
	using WebApplication1.Models;

	namespace WebApplication1.Controllers
	{
	public class MoviesController : Controller
	{
	private MovieDBContext db = new MovieDBContext();

	// GET: Movies/Index?Searchstring={text}
	public ActionResult Index(string searchString)
	{
	var movies = (from m in db.Movies
	select m);
	if(!String.IsNullOrEmpty(searchString))
	{
	movies = movies.Where(s => s.Title.Contains(searchString));
	}
	return View(movies);
	}

	// GET: Movies/Details/5
	public ActionResult Details(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// GET: Movies/Create
	public ActionResult Create()
	{
	return View();
	}

	// POST: Movies/Create
	// To protect from overposting attacks, please enable the specific properties you want to bind to, for
	// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
	[HttpPost]
	[ValidateAntiForgeryToken]
	public ActionResult Create([Bind(Include = "ID,Title,ReleaseDate,Genre,Price")] Movie movie)
	{
	if (ModelState.IsValid)
	{
	db.Movies.Add(movie);
	db.SaveChanges();
	return RedirectToAction("Index");
	}

	return View(movie);
	}

	// GET: Movies/Edit/5
	public ActionResult Edit(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// POST: Movies/Edit/5
	// To protect from overposting attacks, please enable the specific properties you want to bind to, for
	// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
	[HttpPost]
	[ValidateAntiForgeryToken]
	public ActionResult Edit([Bind(Include = "ID,Title,ReleaseDate,Genre,Price")] Movie movie)
	{
	if (ModelState.IsValid)
	{
	db.Entry(movie).State = EntityState.Modified;
	db.SaveChanges();
	return RedirectToAction("Index");
	}
	return View(movie);
	}

	// GET: Movies/Delete/5
	public ActionResult Delete(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// POST: Movies/Delete/5
	[HttpPost, ActionName("Delete")]
	[ValidateAntiForgeryToken]
	public ActionResult DeleteConfirmed(int id)
	{
	Movie movie = db.Movies.Find(id);
	db.Movies.Remove(movie);
	db.SaveChanges();
	return RedirectToAction("Index");
	}

	protected override void Dispose(bool disposing)
	{
	if (disposing)
	{
	db.Dispose();
	}
	base.Dispose(disposing);
	}
	}
	}

view raw MoviesController.cs hosted with ❤ by GitHub

1. 在網址列輸入"http://{localhost:port}/Movies/Index?searchString={searchString}"，按下Enter重新載入頁面即會顯示影片標題內含所搜尋字串的影片。

᳓實作2. 修改Views/Movies/Index.cshtml
然而經由修改URL的方式搜尋太不直覺，因此要在Index.cshtml頁面直接加入UI，提供輸入欄位以及控制按鈕，方便使用。

	@model IEnumerable<WebApplication1.Models.Movie>

	@{
	ViewBag.Title = "Index";
	}

	<h2>Index</h2>

	<p>
	@Html.ActionLink("Create New", "Create")
	@using (Html.BeginForm())
	{
	<p>
	Title:@Html.TextBox("SearchString")<br />
	<input type="submit" value="Filter" />
	</p>
	}
	</p>
	<table class="table">
	<tr>
	<th>
	@Html.DisplayNameFor(model => model.Title)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.ReleaseDate)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Genre)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Price)
	</th>
	<th></th>
	</tr>

	@foreach (var item in Model) {
	<tr>
	<td>
	@Html.DisplayFor(modelItem => item.Title)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.ReleaseDate)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Genre)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Price)
	</td>
	<td>
	@Html.ActionLink("Edit", "Edit", new { id=item.ID }) \|
	@Html.ActionLink("Details", "Details", new { id=item.ID }) \|
	@Html.ActionLink("Delete", "Delete", new { id=item.ID })
	</td>
	</tr>
	}

	</table>

view raw Index.cshtml hosted with ❤ by GitHub

1. 一進入頁面就可以看到"BeginForm()"被編譯成<form>，其下含"TextBox()"被編譯成<input type="text">，以及<input type="submit">。(此時可直接利用UI進行搜尋，不需要添加與修改URL中的參數，Controller在執行時會自動取用對應id的元件值，若是將@Html.TextBox("searchString")改為@Html.TextBox("searchStrings")便會無法進行搜尋)

᳓實作3. 修改Views/Movies/Index.cshtml
光只是加入UI仍然沒有提供好的使用體驗，因為當使用者想要將搜尋結果分享給其他人的時候卻發現複製到的URL中並沒有附帶參數，不能夠直接顯示出搜尋的結果，所以要再進行一點修正，使用BeginForm("{Action Name}", "{Controller Name}", FormMethod.Get)。

	@model IEnumerable<WebApplication1.Models.Movie>

	@{
	ViewBag.Title = "Index";
	}

	<h2>Index</h2>

	<p>
	@Html.ActionLink("Create New", "Create")
	@using (Html.BeginForm("Index", "Movies", FormMethod.Get))
	{
	<p>
	標題：@Html.TextBox("searchString")<br />
	<input type="submit" value="搜尋" />
	</p>
	}
	</p>
	<table class="table">
	<tr>
	<th>
	@Html.DisplayNameFor(model => model.Title)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.ReleaseDate)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Genre)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Price)
	</th>
	<th></th>
	</tr>

	@foreach (var item in Model) {
	<tr>
	<td>
	@Html.DisplayFor(modelItem => item.Title)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.ReleaseDate)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Genre)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Price)
	</td>
	<td>
	@Html.ActionLink("Edit", "Edit", new { id=item.ID }) \|
	@Html.ActionLink("Details", "Details", new { id=item.ID }) \|
	@Html.ActionLink("Delete", "Delete", new { id=item.ID })
	</td>
	</tr>
	}

	</table>

view raw Index.cshtml hosted with ❤ by GitHub

1. 按下搜尋按鈕後，URL會自動添加"?searchString={searchString}"，因此該網址可直接複製至新頁面使用。

᳓實作4. 修改Controllers/MoviesController.cs、Views/Movies/Index.cshtml
接著練習加入下拉式選單至頁面中。利用LINQ query搜尋資料表中所有的類型，接著以Distinct()將重複的選項剔除後加入至List，最後將List的資料用ViewBag.SelectList({Collection.IEnumerable items}, "{Selected Value}")代入至View並顯示。

	using System;
	using System.Collections.Generic;
	using System.Data;
	using System.Data.Entity;
	using System.Linq;
	using System.Net;
	using System.Web;
	using System.Web.Mvc;
	using WebApplication1.Models;

	namespace WebApplication1.Controllers
	{
	public class MoviesController : Controller
	{
	private MovieDBContext db = new MovieDBContext();

	// GET: Movies/Index?searchString={text}
	public ActionResult Index(string movieGenre, string searchString)
	{
	var GenreLst = new List<string>();
	var GenreQry = (from d in db.Movies
	orderby d.Genre
	select d.Genre);
	GenreLst.AddRange(GenreQry.Distinct());
	ViewBag.movieGenre = new SelectList(GenreLst, "愛情片");

	var movies = (from m in db.Movies
	select m);
	if (!String.IsNullOrEmpty(movieGenre))
	{
	movies = movies.Where(s => s.Genre == movieGenre);
	}
	if(!String.IsNullOrEmpty(searchString))
	{
	movies = movies.Where(s => s.Title.Contains(searchString));
	}
	return View(movies);
	}

	// GET: Movies/Details/5
	public ActionResult Details(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// GET: Movies/Create
	public ActionResult Create()
	{
	return View();
	}

	// POST: Movies/Create
	// To protect from overposting attacks, please enable the specific properties you want to bind to, for
	// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
	[HttpPost]
	[ValidateAntiForgeryToken]
	public ActionResult Create([Bind(Include = "ID,Title,ReleaseDate,Genre,Price")] Movie movie)
	{
	if (ModelState.IsValid)
	{
	db.Movies.Add(movie);
	db.SaveChanges();
	return RedirectToAction("Index");
	}

	return View(movie);
	}

	// GET: Movies/Edit/5
	public ActionResult Edit(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// POST: Movies/Edit/5
	// To protect from overposting attacks, please enable the specific properties you want to bind to, for
	// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
	[HttpPost]
	[ValidateAntiForgeryToken]
	public ActionResult Edit([Bind(Include = "ID,Title,ReleaseDate,Genre,Price")] Movie movie)
	{
	if (ModelState.IsValid)
	{
	db.Entry(movie).State = EntityState.Modified;
	db.SaveChanges();
	return RedirectToAction("Index");
	}
	return View(movie);
	}

	// GET: Movies/Delete/5
	public ActionResult Delete(int? id)
	{
	if (id == null)
	{
	return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
	}
	Movie movie = db.Movies.Find(id);
	if (movie == null)
	{
	return HttpNotFound();
	}
	return View(movie);
	}

	// POST: Movies/Delete/5
	[HttpPost, ActionName("Delete")]
	[ValidateAntiForgeryToken]
	public ActionResult DeleteConfirmed(int id)
	{
	Movie movie = db.Movies.Find(id);
	db.Movies.Remove(movie);
	db.SaveChanges();
	return RedirectToAction("Index");
	}

	protected override void Dispose(bool disposing)
	{
	if (disposing)
	{
	db.Dispose();
	}
	base.Dispose(disposing);
	}
	}
	}

view raw MoviesController.cs hosted with ❤ by GitHub

	@model IEnumerable<WebApplication1.Models.Movie>

	@{
	ViewBag.Title = "Index";
	}

	<h2>Index</h2>

	<p>
	@Html.ActionLink("Create New", "Create")
	@using (Html.BeginForm("Index", "Movies", FormMethod.Get))
	{
	<p>
	類型：@Html.DropDownList("movieGenre", "全部")
	標題：@Html.TextBox("searchString")<br />
	<input type="submit" value="搜尋" />
	</p>
	}
	</p>
	<table class="table">
	<tr>
	<th>
	@Html.DisplayNameFor(model => model.Title)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.ReleaseDate)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Genre)
	</th>
	<th>
	@Html.DisplayNameFor(model => model.Price)
	</th>
	<th></th>
	</tr>

	@foreach (var item in Model) {
	<tr>
	<td>
	@Html.DisplayFor(modelItem => item.Title)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.ReleaseDate)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Genre)
	</td>
	<td>
	@Html.DisplayFor(modelItem => item.Price)
	</td>
	<td>
	@Html.ActionLink("Edit", "Edit", new { id=item.ID }) \|
	@Html.ActionLink("Details", "Details", new { id=item.ID }) \|
	@Html.ActionLink("Delete", "Delete", new { id=item.ID })
	</td>
	</tr>
	}

	</table>

view raw Index.cshtml hosted with ❤ by GitHub

1. 一進入頁面就可以看到"DropDownList()"被編譯成<select>，除了資料庫中的類型外還增加了"全部"的選項，且預設選取"愛情片"。

2018年3月18日星期日

C# － Function傳值和傳址的小測試

᳓重點整理
這是function透過傳值和傳址兩種方式傳入參數的小測試。傳值是只將function的參數值，設定成與輸入變數的值相同；而傳址則是直接將輸入變數作為function的參數使用，因此會造就以下幾點不同：

以傳值方式傳入的參數，在function中修改參數值也不會影響到輸入變數。
以傳址方式傳入的參數，在function中修改參數值會影響到輸入變數。
傳值跟傳址的function即使同名也視為不同的function，可正確執行。

᳓實作1. 建立專案
建立一個Windows Forms Application專案，並在Form拉入兩個Label、兩個Button。

᳓實作2. 修改FunctionRefTest.cs
加入兩個Button_Click事件、兩個function，並輸入以下程式碼，測試重點為在function中會修改參數值，並於function執行完畢後輸出變數值。

	using System;
	using System.Collections.Generic;
	using System.ComponentModel;
	using System.Data;
	using System.Drawing;
	using System.Linq;
	using System.Text;
	using System.Threading.Tasks;
	using System.Windows.Forms;

	namespace WindowsFormsApplication_FunctionRefTest
	{
	public partial class FunctionRefTest : Form
	{
	public FunctionRefTest()
	{
	InitializeComponent();
	}

	private void button1_Click(object sender, EventArgs e)
	{
	int r = 4;
	double result = CalculateArea(r);
	MessageBox.Show("傳值: " + r + " " + result); // "傳值: 4 16"
	}

	static double CalculateArea(int r)
	{
	double Volume = r * r;
	r = r + 1;
	return Volume;
	}

	private void button2_Click(object sender, EventArgs e)
	{
	int p = 4;
	double result = CalculateArea(ref p);
	MessageBox.Show("傳址: " + p + " " + result); // "傳址: 5 16"
	}

	static double CalculateArea(ref int p)
	{
	double Volume = p * p;
	p = p + 1;
	return Volume;
	}
	}
	}

view raw FunctionRefTest.cs hosted with ❤ by GitHub

傳值測試：輸入變數值為4，輸出時不變。

傳址測試：輸入變數值為4，輸出時已被修改。

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標籤

2018年6月4日 星期一

ASP.NET MVC 5 － Adding Validation

2018年4月3日 星期二

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2018年3月26日 星期一

ASP.NET MVC 5 － Adding a Search

2018年3月18日 星期日

C# － Function傳值和傳址的小測試

2018年6月4日星期一

2018年4月3日星期二

2018年3月26日星期一

2018年3月18日星期日