從Page_Load到One_Method和從One_Method到Another_Method

Question

嘿，我用完整的代碼提出了一個更多的問題，因爲我在這一點上真的被困住了。 當頁面加載面板時填充了從數據庫中取得的書籍類別。這個類別也是鏈接按鈕。當我點擊一個類別時，將在下面創建一個表格，其中包含該類別的所有書籍。 在該表格中，第一個單元格充滿了書籤標題，它也是Linkbutton。 我只是想當我點擊那本書的標題linkbutton來觸發book_Details函數 ，以便頁面現在只顯示我選擇的書。

取而代之的是，每當我再次點擊從0

的標記books'title LinkBut​​ton的頁面加載是：

<asp:Content ID="Content3" ContentPlaceHolderID="MainContent" runat="server"> 
<div style="position: relative; top: 5%; left: 5%;"> 
    <asp:Panel ID="MyPanel" runat="server"></asp:Panel> 
</div> 
<asp:MultiView ID="MultiView2" runat="server"> 
    <asp:View ID="View1" runat="server"> 
     <div style="overflow: auto; height: 400px;"> 
      <asp:Table ID="ProductTBL" runat="server" BorderColor="Black" BorderStyle="Double" CellPadding="5" CellSpacing="5" BorderWidth="1px"> 
      </asp:Table> 
     </div> 
    </asp:View> 
    <asp:View ID="View2" runat="server"> 
     <asp:Table ID="detail_TBL" runat="server" BorderColor="Black" BorderStyle="Double" CellPadding="5" CellSpacing="5" BorderWidth="1px"></asp:Table> 
    </asp:View> 
</asp:MultiView> 
</asp:Content> 

和代碼隱藏的是：

protected void Page_Load(object sender, EventArgs e) 
{ 
    String conString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source =" + 
       Server.MapPath("~/e-bookstoredb.accdb"); 
    using (OleDbConnection connection = new OleDbConnection(conString)) 
    { 
     connection.Open(); 

     ыtring query = "SELECT * FROM category"; 
     using (OleDbCommand cmd = new OleDbCommand(query, connection)) 
     { 
      OleDbDataReader reader = cmd.ExecuteReader(); 
      while (reader.Read()) 
      { 
       string literal = (string)reader["Name"]; 

       LinkButton lnk_button = new LinkButton(); 
       lnk_button.Text = literal; 
       lnk_button.ID = "cat_B" + reader["ID"].ToString(); 
       lnk_button.CommandArgument = reader["ID"].ToString(); 
       lnk_button.CommandName = reader["ID"].ToString(); 
       lnk_button.Command += new CommandEventHandler(books_Show); 

       MyPanel.Controls.Add(lnk_button); 
       MyPanel.Controls.Add(new LiteralControl("</br>")); 
      } 
      reader.Close(); 
     } 
     connection.Close(); 
    } 
} 

protected void books_Show(object sender, EventArgs e) 
{ 
    LinkButton lnk = sender as LinkButton; 
    string cat = lnk.CommandArgument; 
    MultiView2.ActiveViewIndex = 0; 

    string ConStr = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source =" + Server.MapPath("~/e-bookstoredb.accdb"); 
    using (OleDbConnection con = new OleDbConnection(ConStr)) 
    { 
     con.Open(); 
     string query = "SELECT * FROM product WHERE category = @cat"; 
     using (OleDbCommand cmd = new OleDbCommand(query, con)) 
     { 
      cmd.Parameters.AddWithValue("@cat", cat); 
      OleDbDataReader reader = cmd.ExecuteReader(); 
      TableCell cell; 

      TableRow row = new TableRow(); 
      TableCell titleCell = new TableCell(); 
      titleCell.Text = "Τίτλος"; 

      TableCell desCell = new TableCell(); 
      desCell.Text = "Περιγραφή"; 
      TableCell priceCell = new TableCell(); 
      priceCell.Text = "Τιμή"; 

      row.Cells.Add(titleCell); 
      row.Cells.Add(desCell); 
      row.Cells.Add(priceCell); 

      ProductTBL.Rows.Add(row); 
      LinkButton book_button; 

      while (reader.Read()) 
      { 
       book_button = new LinkButton(); 
       book_button.ID = "book" + reader["ID"].ToString(); 
       book_button.Text = (string)reader["Title"]; 
       book_button.CommandArgument = (string) reader["Title"]; 
       book_button.CommandName = "cmd" + reader["ID"].ToString(); 
       book_button.Command += new CommandEventHandler(book_Details); 

       row = new TableRow(); 

       cell = new TableCell(); 
       cell.Controls.Add(book_button); 
       row.Cells.Add(cell); 

       cell = new TableCell(); 
       cell.Text = (string)reader["Description"]; 
       row.Cells.Add(cell); 

       cell = new TableCell(); 
       cell.Text = reader["price"].ToString()+"€"; 
       row.Cells.Add(cell); 

       ProductTBL.Rows.Add(row); 
      } 
      reader.Close(); 
     } 
     con.Close(); 
    } 
} 

protected void book_Details(object sender, EventArgs e) 
{ 
    MultiView2.ActiveViewIndex = 1; 
    LinkButton lnk = sender as LinkButton; 
    String bookTitle = lnk.CommandArgument; 
    //...And then I just create a table to show only the book user selected 
    //...this table gets filled buy this query = " SELECT * FROM product WHERE Title=@bookTitle 
} 

Answer 1

你必須將您的代碼包含在Page_Load之內if(!IsPostBack)如下所示。這是因爲根據ASP.Net頁面生命週期，Page_Load會首先觸發並控制事件發生。

因此，無論何時您單擊LinkButtons服務器首先調用Page_Load，然後它調用LinkButton的單擊事件。

因此，將Page_Load代碼包裝在Page_Load這樣的代碼中是一個不錯的主意。

protected void Page_Load(object sender, EventArgs e) 
{ 
    if (!IsPostBack) 
    { 
     // Your Page_Load logic goes here 
    } 
} 

根據MSDN爲IsPostBack的定義是

獲取一個值，用於指示該頁面是否正被渲染爲 第一次或響應於回發被加載。

true如果正在加載頁面以響應客戶端回發; 否則，false。

希望這有助於！