ASP.NET Core MVC 打造一個簡單的圖書館管理系統 (修正版)（四）圖書信息的增刪改查

時間 2019-11-10

標籤 asp.net asp core mvc 打造一個簡單圖書館管理系統修正圖書信息增刪欄目 ASP 简体版

原文原文鏈接

前言：javascript

本系列文章主要爲我以前所學知識的一次微小的實踐，以我學校圖書館管理系統爲雛形所做。css

本系列文章主要參考資料：html

微軟文檔：https://docs.microsoft.com/zh-cn/aspnet/core/getting-started/?view=aspnetcore-2.1&tabs=windowsjava

《Pro ASP.NET MVC 5》、《鋒利的 jQuery》git

此係列皆使用 VS2017+C# 做爲開發環境。若是有什麼問題或者意見歡迎在留言區進行留言。 github

項目 github 地址：https://github.com/NanaseRuri/LibraryDemowindows

本章內容：分頁、自定義 HtmlHelper、經過模態窗口確認是否提交表單、上傳文件、獲取文件、預覽文件、select 元素、表單提交數組、checkbox、js 確認關閉頁面數組

注：在對 EF 中的數據進行更改時，須要調用對應 Context 的 SaveChange 方法才能對更改進行保存。瀏覽器

1、視圖分頁視圖模型session

首先建立一個視圖模型用於肯定每頁的書籍數、頁數

 1     public class PagingInfo
 2     {
 3         public int TotalItems { get; set; }
 4         public int ItemsPerPage { get; set; }
 5         public int CurrentPage { get; set; }
 6 
 7         public int TotalPages
 8         {
 9             get => (int)Math.Ceiling((decimal)TotalItems / ItemsPerPage);
10         }
11     }

而後建立另外一個視圖模型用於肯定該分頁信息以及各分頁的書籍：

1      public class BookListViewModel
2      {
3          public IEnumerable<BookDetails> BookDetails { get; set; }
4          public PagingInfo PagingInfo { get; set; }
5      }

建立一個自定義 HtmlHelper 用於在視圖中使用 Razor 語法獲取分頁，在 ASP.NET Core 中 TagBuilder 繼承自 IHtmlContent，不能直接對 TagBuilder 進行賦值，需調用 MergeAttribute 方法和 InnerHtml 屬性的 AppendHtml 方法編寫標籤；而且 TagBuilder 沒有實現 ToString 方法，只能經過其 WriteTo 方法將內容寫到一個 TextWriter 對象中以取出其值：

 1     public static class PagingHelper
 2     {
 3         public static HtmlString PageLinks(this IHtmlHelper html, PagingInfo pagingInfo, Func<int, string> pageUrl)
 4         {
 5             StringWriter writer=new StringWriter();
 6             for (int i = 1; i <= pagingInfo.TotalPages; i++)
 7             {
 8                 TagBuilder tag=new TagBuilder("a");
 9                 tag.MergeAttribute("href",pageUrl(i));
10                 tag.InnerHtml.AppendHtml(i.ToString());
11                 if (i==pagingInfo.CurrentPage)
12                 {
13                     tag.AddCssClass("selected");
14                     tag.AddCssClass("btn-primary");
15                 }
16                 tag.AddCssClass("btn btn-default");
17                 tag.WriteTo(writer,HtmlEncoder.Default);
18             }
19             return new HtmlString(writer.ToString());
20         }
21     }

2、編輯圖書信息頁面的首頁

在此準備使用 Session 更快地獲取圖書信息，爲了在使用時更直觀，此處對 Session 類進行擴展：

 1     public static class SessionExtensions
 2     {
 3         public static void Set<T>(this ISession session, string key, T value)
 4         {
 5             session.SetString(key, JsonConvert.SerializeObject(value));
 6         }
 7 
 8         public static T Get<T>(this ISession session, string key)
 9         {
10             var value = session.GetString(key);
11             return value == null ? default(T) : JsonConvert.DeserializeObject<T>(value);
12         }
13     }

建立一個 BookInfo 控制器:

1    public class BookInfoController : Controller
2     {
3         private LendingInfoDbContext _lendingInfoDbContext;
4 
5         public BookInfoController(LendingInfoDbContext context)
6         {
7             _lendingInfoDbContext = context;
8         }
9     }

建立學生瀏覽的首頁：

在此使用 Session 獲取書籍列表：

建立 BookInfo 控制器並肯定其中每一個分頁的書籍數，使用 Session 獲取更快地獲取書籍信息：

 1     public class BookInfoController : Controller
 2  { 3 private LendingInfoDbContext _context; 4 private static int amout = 4; 5 6 public BookInfoController(LendingInfoDbContext context) 7  { 8 _context = context; 9  } 10 11 public IActionResult Index(string category, int page = 1) 12  { 13 IEnumerable<BookDetails> books = null; 14 if (HttpContext.Session != null) 15  { 16 books = HttpContext.Session.Get<IEnumerable<BookDetails>>("bookDetails"); 17  } 18 if (books == null) 19  { 20 books = _context.BooksDetail; 21 HttpContext.Session?.Set<IEnumerable<BookDetails>>("books", books); 22  } 23 BookListViewModel model = new BookListViewModel() 24  { 25 PagingInfo = new PagingInfo() 26  { 27 ItemsPerPage = amout, 28 TotalItems = books.Count(), 29 CurrentPage = page, 30  }, 31 BookDetails = books.OrderBy(b => b.FetchBookNumber).Skip((page - 1) * amout).Take(amout) 32  }; 33 return View(model); 34  } 35 36 public FileContentResult GetImage(string isbn) 37  { 38 BookDetails target = _context.BooksDetail.FirstOrDefault(b => b.ISBN == isbn); 39 if (target != null) 40  { 41 return File(target.ImageData, target.ImageMimeType); 42  } 43 return null; 44  } 45 }

視圖頁面：

33 行利用 BookListViewModel 中 PagingInfo 的 CurrentPage 獲取各序號，32 行中使 img 元素的 src 指向 BookInfoController 的 GetImage 方法以獲取圖片：

 1 @using LibraryDemo.HtmlHelpers
 2 @model BookListViewModel
 3 @{
 4     ViewData["Title"] = "Index";
 5     int i = 1;
 6     Layout = "_LendingLayout";
 7 }
 8 <style type="text/css">
 9     tr > td {
10         padding: 5px;
11         padding-left: 20px;
12     }
13     tr+tr {
14         border-top: thin solid black;
15         padding-top: 10px;
16     }
17 </style>
18 
19 <hr />
20 <table>
21     <tbody>
22     @foreach (var book in Model.BookDetails)
23     {
24         <tr>
25             <td style="width: 3%">@((@Model.PagingInfo.CurrentPage-1)*4+i++)</td>
26             <td style="text-align: center; width: 150px; height: 200px;">
27                 @if (book.ImageData == null)
28                 {
29                     <label>No Image</label>
30                 }
31                 else
32                 {
33                     <img class="img-thumbnail pull-left" src="@Url.Action("GetImage", "BookInfo", new {book.ISBN})" />
34                 }   
35             </td>
36             <td style="text-align: left;">
37                 <a style="margin-left: 1em;" href="@Url.Action("Detail",new{isbn=@book.ISBN})">@book.Name</a>
38                 <div style="margin-left: 2em;margin-top: 5px">
39                     <span>@book.Author</span>
40                     <br />
41                     <span>@book.Press</span>
42                     <p>@book.FetchBookNumber</p>
43                 </div>
44                 <div style="text-indent: 2em">
45                     <p>@book.Description</p>
46                 </div>
47             </td>
48         </tr>
49     }
50     </tbody>    
51 </table>    
52 <div class="btn-group pull-right">
53     @Html.PageLinks(Model.PagingInfo, x => Url.Action("Index", new { page = x}))
54 </div>

在此一樣使用 Session 獲取書籍列表：

利用 [Authorize] 特性指定 Role 屬性確保只有 Admin 身份的人才能訪問該頁面：

 1         [Authorize(Roles = "Admin")]
 2         public IActionResult BookDetails(string isbn, int page = 1)
 3         {
 4             IEnumerable<BookDetails> books = null;
 5             BookListViewModel model;
 6             if (HttpContext.Session != null)
 7             {
 8                 books = HttpContext.Session.Get<IEnumerable<BookDetails>>("bookDetails");
 9             }
10             if (books == null)
11             {
12                 books = _context.BooksDetail.AsNoTracking();
13                 HttpContext.Session?.Set<IEnumerable<BookDetails>>("books", books);
14 
15             }
16             if (isbn != null)
17             {
18                 model = new BookListViewModel()
19                 {
20                     BookDetails = new List<BookDetails>() { books.FirstOrDefault(b => b.ISBN == isbn) },
21                     PagingInfo = new PagingInfo()
22                 };
23                 return View(model);
24             }
25             model = new BookListViewModel()
26             {
27 
28                 PagingInfo = new PagingInfo()
29                 {
30                     ItemsPerPage = amout,
31                     TotalItems = books.Count(),
32                     CurrentPage = page,
33                 },
34                 BookDetails = books.OrderBy(b => b.FetchBookNumber).Skip((page - 1) * amout).Take(amout)
35             };
36             return View(model);
37         }

BookDetails 視圖，confirmDelete 爲刪除按鈕添加了確認的模態窗口；

53 行爲 glyphicon 爲 Bootstrap 提供的免費圖標，只能經過 span 元素使用：

 1     @using LibraryDemo.HtmlHelpers
 2     @model BookListViewModel
 3     @{
 4         ViewData["Title"] = "BookDetails";
 5         int i = 1;
 6     }
 7 
 8     <script>
 9         function confirmDelete() {
10             var isbns = document.getElementsByName("isbns");
11             var message="確認刪除";
12             for (i in isbns) {
13                 if (isbns[i].checked) {
14                     var book = isbns[i].parentElement.nextElementSibling.nextElementSibling.firstElementChild.innerHTML;
15                     message=message+"《"+book+"》";
16                 }
17             }
18             message = message + "?";
19             if (confirm(message) == true) {
20                 return true;
21             } else {
22                 return false;
23             }
24         }
25     </script>
26 
27     <style type="text/css">
28         tr + tr {
29             border-top: thin solid gray;
30         }
31 
32         .container {
33             width: 1200px;
34         }
35     </style>
36 
37 
38     <hr />
39     @if (TempData["message"] != null)
40     {
41         <p>@TempData["message"]</p>
42         <br />
43         <br />
44     }
45     <form class="pull-left" action="@Url.Action("Search")">
46         @Html.DropDownList("keyword",new List<SelectListItem>()
47         {
48             new SelectListItem("書名","Name"),
49             new SelectListItem("ISBN","ISBN"),
50             new SelectListItem("索書號","FetchBookNumber"),
51         })
52         <input type="text" name="value"/>
53         <button type="submit"><span class="glyphicon glyphicon-search"></span></button>
54     </form>
55     <br />
56     <br />
57 
58     <form method="post" asp-action="RemoveBooksAndBookDetails">
59         <table width="1000">
60             <tbody>
61             <tr>
62                 <th></th>
63                 <th >序號</th>
64                 <th>標題</th>
65                 <th ></th>
66                 <th style="text-align: right">ISBN</th>            
67             </tr>
68             @foreach (var book in Model.BookDetails)
69             {
70                 <tr>
71                     <td><input type="checkbox" name="isbns" value="@book.ISBN" /></td>
72                     <td style=" padding-left: 10px">@((Model.PagingInfo.CurrentPage-1)*4+i++)</td>
73                     <td><a asp-action="EditBookDetails" asp-route-isbn="@book.ISBN">@book.Name</a></td>
74                     <td></td>
75                     <td style="text-align: right;">@book.ISBN</td>                
76                 </tr>
77             }
78             </tbody>
79         </table>
80         <br/>
81         <div>
82             <a class="btn btn-primary" href="@Url.Action("AddBookDetails")">添加書籍</a>
83             <button type="submit" class="btn btn-danger" onclick="return confirmDelete()"> 刪除書籍</button>        
84         </div>
85     </form>
86 
87     <br />
88     <div class="btn-group pull-right">
89         @Html.PageLinks(Model.PagingInfo, x => Url.Action("BookDetails", new { page = x }))
90     </div>

Index 頁面：

BookDetails 頁面：

3、添加書籍信息

在此爲了接受圖片須要使用 IFormFile 接口，爲了使圖片以原有的格式在瀏覽器中顯示，須要用另外一個字段 ImageType 保存文件的格式；

39 頁使用 TempData 傳遞一次性信息告知書籍添加成功，在傳遞完成後 TempData 將被當即釋放：

 1         [Authorize(Roles = "Admin")]
 2         public IActionResult AddBookDetails(BookDetails model)
 3         {
 4             if (model == null)
 5             {
 6                 model = new BookDetails();
 7             }
 8             return View(model);
 9         }
10 
11         [HttpPost]
12         [ValidateAntiForgeryToken]
13         [Authorize(Roles = "Admin")]
14         public async Task<IActionResult> AddBookDetails(BookDetails model, IFormFile image)
15         {
16             BookDetails bookDetails = new BookDetails();
17             if (ModelState.IsValid)
18             {
19                 if (image != null)
20                 {
21                     bookDetails.ImageMimeType = image.ContentType;
22                     bookDetails.ImageData = new byte[image.Length];
23                     await image.OpenReadStream().ReadAsync(bookDetails.ImageData, 0, (int)image.Length);
24                 }
25 
26                 bookDetails.ISBN = model.ISBN;
27                 bookDetails.Name = model.Name;
28                 bookDetails.Author = model.Author;
29                 bookDetails.Description = model.Description;
30                 bookDetails.FetchBookNumber = model.FetchBookNumber;
31                 bookDetails.Press = model.Press;
32                 bookDetails.PublishDateTime = model.PublishDateTime;
33                 bookDetails.SoundCassettes = model.SoundCassettes;
34                 bookDetails.Version = model.Version;
35 
36                 await _lendingInfoDbContext.BooksDetail.AddAsync(bookDetails);
37 
38                 _lendingInfoDbContext.SaveChanges();
39                 TempData["message"] = $"已添加書籍《{model.Name}》";
40                 return RedirectToAction("EditBookDetails");
41             }
42             return View(model);
43         }

AddBookDetails 視圖：

爲了使表單能夠上傳文件，須要指定表單的 enctype 屬性值爲 multipart/form-data，66 行中使用一個 a 元素包含用來上傳文件的 input ，指定其 class 爲 btn 以生成一個按鈕，指定 href="javascript:;" 使該元素不會返回任何值。

指定 input 的 name 屬性爲 image 以在上傳表單時進行模型綁定，指定其 accept 屬性令其打開文件選擇框時只接收圖片。

JS 代碼爲 input 添加 onchange 事件以預覽上傳的圖片，併爲關閉或刷新頁面時添加模態窗口進行確認，同時爲提交按鈕添加事件以重置 window.onbeforeunload 事件從而不彈出確認窗口：

 1 @model LibraryDemo.Models.DomainModels.BookDetails
 2 @{
 3     ViewData["Title"] = "AddBookDetails";
 4 }
 5 
 6 <script>
 7     function preview(file) {
 8         $(".image").addClass("hidden");
 9         $('.preview').wrap("<div></div>");
10         $(".preview").removeClass("hidden");
11         if (file.files && file.files[0]) {
12             var reader = new FileReader();
13             reader.onload = function (evt) {
14                 $('.preview').attr('src', evt.target.result);
15             }
16             reader.readAsDataURL(file.files[0]);
17         } else {
18             $('.preview').attr('src', file.value);
19         }
20     }        
21     window.onbeforeunload = function () {
22         return "您的數據未保存，肯定退出？";
23     }
24     function removeOnbeforeunload() {
25         window.onbeforeunload = "";
26     }
27 </script>
28 
29 <h2>添加書籍</h2>
30 
31 <form enctype="multipart/form-data" method="post">
32     <div class="panel-body">
33         <div class="form-group">
34             @Html.LabelFor(m => m.ISBN)
35             @Html.TextBoxFor(m => m.ISBN, new { @class = "form-control" })
36         </div>
37         <div class="form-group">
38             @Html.LabelFor(m => m.Name)
39             @Html.TextBoxFor(m => m.Name, new { @class = "form-control" })
40         </div>
41         <div class="form-group">
42             @Html.LabelFor(m => m.Author)
43             @Html.TextBoxFor(m => m.Author, new { @class = "form-control" })
44         </div>
45         <div class="form-group">
46             @Html.LabelFor(m => m.Press)
47             @Html.TextBoxFor(m => m.Press, new { @class = "form-control" })
48         </div>
49         <div class="form-group">
50             @Html.LabelFor(m => m.FetchBookNumber)
51             @Html.TextBoxFor(m => m.FetchBookNumber, new { @class = "form-control" })
52         </div>
53         <div class="form-group">
54             @Html.LabelFor(m => m.SoundCassettes)
55             @Html.TextBoxFor(m => m.SoundCassettes, new { @class = "form-control" })
56         </div>
57         <div class="form-group">
58             @Html.LabelFor(m => m.Description)
59             @Html.TextAreaFor(m => m.Description, new { @class = "form-control", rows = 5 })
60         </div>
61         <div class="form-group">
62             @Html.LabelFor(m => m.PublishDateTime)
63             <div>@Html.EditorFor(m => m.PublishDateTime)</div>
64         </div>
65         <div class="form-group">
66             @Html.LabelFor(m => m.Version)
67             <div>@Html.EditorFor(m => m.Version)</div>
68         </div>
69         <div class="form-group">
70             <div style="position: relative;">
71                 <label>Image</label>
72                 <a class="btn" href="javascript:;">
73                     選擇圖片
74                     <input type="file" name="Image" size="40" accept="image/*"
75                            style="position: absolute; z-index: 2; top: 0; left: 0; filter: alpha(opacity=0); opacity: 0; background-color: transparent; color: transparent"
76                            onchange="preview(this)" />
77                 </a>
78                 <img style="width: 150px;" class="hidden preview img-thumbnail">
79             </div>
80         </div>        
81         <input type="submit" onclick="removeOnbeforeunload()"/>
82     </div>
83 </form>

結果：

4、刪除書籍信息

刪除書籍的動做方法：

此處經過在以前的 BookDetails 視圖中指定 input 元素的 type 爲 checkbox，指定 name 爲 isbns 以實現多個字符串的模型綁定：

 1         [Authorize(Roles = "Admin")]
 2         [HttpPost]
 3         [ValidateAntiForgeryToken]
 4         public async Task<IActionResult> RemoveBooksAndBookDetails(IEnumerable<string> isbns)
 5         {
 6             StringBuilder sb = new StringBuilder();
 7             foreach (var isbn in isbns)
 8             {
 9                 BookDetails bookDetails = _lendingInfoDbContext.BooksDetail.First(b => b.ISBN == isbn);
10                 IQueryable<Book> books = _lendingInfoDbContext.Books.Where(b => b.ISBN == isbn);
11                 _lendingInfoDbContext.BooksDetail.Remove(bookDetails);
12                 _lendingInfoDbContext.Books.RemoveRange(books);
13                 sb.Append("《" + bookDetails.Name + "》");
14                 await _lendingInfoDbContext.SaveChangesAsync();
15             }
16             TempData["message"] = $"已移除書籍{sb.ToString()}";
17             return RedirectToAction("BookDetails");
18         }

結果：

5、編輯書籍信息

動做方法：

 1         [Authorize(Roles = "Admin")]
 2         public async Task<IActionResult> EditBookDetails(string isbn)
 3         {
 4             BookDetails book = await _lendingInfoDbContext.BooksDetail.FirstOrDefaultAsync(b => b.ISBN == isbn);
 5             if (book != null)
 6             {
 7                 return View(book);
 8             }
 9             else
10             {
11                 return RedirectToAction("BookDetails");
12             }
13         }
14 
15         [HttpPost]
16         [ValidateAntiForgeryToken]
17         [Authorize(Roles = "Admin")]
18         public async Task<ActionResult> EditBookDetails(BookDetails model, IFormFile image)
19         {
20             BookDetails bookDetails = _lendingInfoDbContext.BooksDetail.FirstOrDefault(b => b.ISBN == model.ISBN);
21             if (ModelState.IsValid)
22             {
23                 if (bookDetails != null)
24                 {
25                     if (image != null)
26                     {
27                         bookDetails.ImageMimeType = image.ContentType;
28                         bookDetails.ImageData = new byte[image.Length];
29                         await image.OpenReadStream().ReadAsync(bookDetails.ImageData, 0, (int)image.Length);
30                     }
31 
32                     BookDetails newBookDetails = model;
33 
34                     bookDetails.Name = newBookDetails.Name;
35                     bookDetails.Author = newBookDetails.Author;
36                     bookDetails.Description = newBookDetails.Description;
37                     bookDetails.FetchBookNumber = newBookDetails.FetchBookNumber;
38                     bookDetails.Press = newBookDetails.Press;
39                     bookDetails.PublishDateTime = newBookDetails.PublishDateTime;
40                     bookDetails.SoundCassettes = newBookDetails.SoundCassettes;
41                     bookDetails.Version = newBookDetails.Version;
42 
43                     await _lendingInfoDbContext.SaveChangesAsync();
44                     TempData["message"] = $"《{newBookDetails.Name}》修改爲功";
45                     return RedirectToAction("EditBookDetails");
46                 }
47             }
48             return View(model);
49         }

此處視圖與以前 AddBookDetails 大體相同，但在此對一些視圖中的 ISBN 字段添加了 readonly 屬性使它們不能被直接編輯：

  1 @model LibraryDemo.Models.DomainModels.BookDetails
  2 
  3 @{
  4     ViewData["Title"] = "EditBookDetails";
  5 }
  6 
  7 <script>
  8     function preview(file) {
  9         $(".image").addClass("hidden");
 10         $('.preview').wrap("<div></div>");
 11         $(".preview").removeClass("hidden");
 12         if (file.files && file.files[0]){  
 13             var reader = new FileReader();  
 14             reader.onload = function(evt){
 15                 $('.preview').attr('src' , evt.target.result);
 16             }    
 17             reader.readAsDataURL(file.files[0]);  
 18         }else{  
 19             $('.preview').attr('src' , file.value);
 20         }
 21     }
 22     window.onload = function() {
 23         $("div>input").addClass("form-control");
 24         var isbn = document.getElementById("ISBN");
 25         isbn.setAttribute("readonly","true");
 26     }
 27     window.onbeforeunload = function (event) {
 28         return "您的數據未保存，肯定退出？";
 29     }
 30     function removeOnbeforeunload() {
 31         window.onbeforeunload = "";
 32     }
 33 </script>
 34 
 35 <h2>編輯書籍</h2>
 36 
 37 @section Scripts
 38 {
 39     
 40 }
 41 
 42 <form enctype="multipart/form-data" method="post">
 43     <div class="panel-body">
 44         <div class="form-group">
 45             @Html.LabelFor(m => m.ISBN)
 46             @Html.EditorFor(m => m.ISBN)
 47         </div>
 48         <div class="form-group">
 49             @Html.LabelFor(m => m.Name)
 50             @Html.TextBoxFor(m => m.Name, new {@class = "form-control"})
 51         </div>
 52         <div class="form-group">
 53             @Html.LabelFor(m => m.Author)
 54             @Html.TextBoxFor(m => m.Author, new {@class = "form-control"})
 55         </div>
 56         <div class="form-group">
 57             @Html.LabelFor(m => m.Press)
 58             @Html.TextBoxFor(m => m.Press, new {@class = "form-control"})
 59         </div>
 60         <div class="form-group">
 61             @Html.LabelFor(m => m.FetchBookNumber)
 62             @Html.TextBoxFor(m => m.FetchBookNumber, new {@class = "form-control"})
 63         </div>
 64         <div class="form-group">
 65             @Html.LabelFor(m => m.SoundCassettes)
 66             @Html.TextBoxFor(m => m.SoundCassettes, new {@class = "form-control"})
 67         </div>
 68         <div class="form-group">
 69             @Html.LabelFor(m => m.Description)
 70             @Html.TextAreaFor(m => m.Description, new {@class = "form-control", rows = 5})
 71         </div>
 72         <div class="form-group">
 73             @Html.LabelFor(m => m.PublishDateTime)
 74             <div>@Html.EditorFor(m => m.PublishDateTime)</div>
 75         </div>
 76         <div class="form-group">
 77             @Html.LabelFor(m => m.Version)
 78             <div>@Html.EditorFor(m => m.Version)</div>
 79         </div>
 80         <div class="form-group">
 81             <div style="position: relative;">
 82                 <label>Image</label>
 83                 <a class="btn" href="javascript:;">
 84                     選擇圖片
 85                     <input type="file" name="Image" size="40" accept="image/*"
 86                            style="position: absolute; z-index: 2; top: 0; left: 0; filter: alpha(opacity=0); opacity: 0; background-color: transparent; color: transparent"
 87                            onchange="preview(this)" />
 88                 </a>
 89                 <img style="width: 150px;" class="hidden preview img-thumbnail">
 90             </div>
 91             @if (Model.ImageData == null)
 92             {
 93             <div class="form-control-static image">No Image</div>
 94             }
 95             else
 96             {
 97             <img class="img-thumbnail image" style="width: 150px;" src="@Url.Action("GetImage", "BookInfo", new {Model.ISBN})" />
 98             }
 99         </div>
100         <br />
101         <a class="btn btn-primary" asp-action="Books" asp-route-isbn="@Model.ISBN" onclick="return removeOnbeforeunload()">編輯外借書籍信息</a>
102         <br />
103         <br />
104         <input type="submit" class="btn btn-success" onclick="return removeOnbeforeunload()"/>
105     </div>
106 </form>

結果：

6、查詢特定書籍

此處和以前的帳號登陸處同樣使用 switch 對不一樣的關鍵詞進行檢索：

 1         public async Task<IActionResult> Search(string keyWord, string value)
 2         {
 3             BookDetails bookDetails = new BookDetails();
 4             switch (keyWord)
 5             {
 6                 case "Name":
 7                     bookDetails =await _context.BooksDetail.FirstOrDefaultAsync(b => b.Name == value);
 8                     break;
 9                 case "ISBN":
10                     bookDetails =await _context.BooksDetail.FirstOrDefaultAsync(b => b.ISBN == value);
11                     break;
12                 case "FetchBookNumber":
13                     bookDetails =await _context.BooksDetail.FirstOrDefaultAsync(b => b.FetchBookNumber == value);
14                     break;
15             }
16 
17             if (bookDetails!=null)
18             {
19                 return RedirectToAction("EditBookDetails", new {isbn = bookDetails.ISBN});
20             }
21 
22             TempData["message"] = "找不到該書籍";
23             return RedirectToAction("BookDetails");
24         }

結果：

相關標籤/搜索

每日一句

每一个你不满意的现在，都有一个你没有努力的曾经。