ListView控件--增，刪，改，查

ASP.Net3.5中包含了新的數據綁定控件--ListView，這是一個類似與repeater與gridvIEw結合的控件，可以實現添加，刪除功能，同時還可以像repeater一樣靈活的控制頁面的布局。該控件包含了很多新的模板，比如GroupTemplate等新增的模板，可以方便的分組顯示數據。詳細的大家可以去查MSDN文檔。

我一直認為學習數據綁定控件從最簡單的增刪改查開始，可以對該控件有較深刻的理解，這樣可以舉一反三，在進行綜合運用。今天這篇文章還是從最基本的數據操作開始，對ListVIEw有個感性的認識。

首先看一下程序運行的效果：

頁面源碼：

     <ASP:ListView ID="ListView1" runat="server" OnSelectedIndexChanging="ListVIEw1_SelectedIndexChanging"
            OnItemCommand="ListVIEw1_ItemCommand" 
            OnItemEditing="ListView1_ItemEditing" OnItemCanceling="ListVIEw1_ItemCanceling"
            OnItemDataBound="ListView1_ItemDataBound" OnPagePropertiesChanging="ListView1_PagePropertIEsChanging"
            OnItemInserting="ListView1_ItemInserting" OnItemUpdating="ListVIEw1_ItemUpdating"
            OnSorting="ListView1_Sorting" EnableVIEwState="true" 
            InsertItemPosition="LastItem" onitemdeleting="ListVIEw1_ItemDeleting">
            <LayoutTemplate>
                <asp:PlaceHolder ID="itemPlaceholder" runat="server"></ASP:PlaceHolder>
                <p>
                    <ASP:DataPager ID="MyPage" runat="server" PageSize="6">
                        <FIElds>
                            <ASP:NumericPagerFIEld ButtonCount="10" PreviousPageText="<-- " NextPageText="-->" />
                            <%...--   <ASP:NextPreviousPagerFIEld ButtonType="Button" ShowFirstPageButton="true" ShowLastPageButton="true"
                            ShowNextPageButton="true" ShowPreviousPageButton="true" />--%>
                        </FIElds>
      &n          </ASP:DataPager>
                </p>
            </LayoutTemplate>
            <ItemTemplate>
                <i>
                    <%...#Eval("SupplIErID")%></i>
                <p>
                    <b>
                        <%...#Eval("CompanyName")%></b></p>
                <p>
                    <%...#Eval("ContactName")%></p>
                <p>
                    <%...#Eval("Address")%></p>
                <p>
                    <%...#Eval("City")%></p>
                <ASP:Button ID="btnEdit" runat="server" Text="Edit" CommandName="Edit" />
                <ASP:Button ID="btnDelete" runat="server" Text="Delete" CommandName="Delete" />
                <%...--  <asp:LinkButton ID="lbtnSort" runat="server" Text="Sort" CommandName="Sort" CommandArgument="CompanyName" ></ASP:LinkButton>--%>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtMy" runat="server" Text=''<%#bind("SupplIErID") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox1" runat="server" Text=''<%#bind("CompanyName") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox2" runat="server" Text=''<%#bind("ContactName") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox3" runat="server" Text=''<%#bind("Address") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox4" runat="server" Text=''<%#bind("City") %>''></ASP:TextBox>
                <ASP:Button ID="btnUpdate" runat="server" Text="Update" CommandName="Update" />
                <ASP:Button ID="btnCancle" runat="server" Text="Cancle" CommandName="Cancel" />
            </EditItemTemplate>
&         <InsertItemTemplate>
                <asp:TextBox ID="txtMy" runat="server" Text=''<%#bind("SupplIErID") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox1" runat="server" Text=''<%#bind("CompanyName") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox2" runat="server" Text=''<%#bind("ContactName") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox3" runat="server" Text=''<%#bind("Address") %>''></ASP:TextBox>
                <asp:TextBox ID="TextBox4" runat="server" Text=''<%#bind("City") %>''></ASP:TextBox>
                <ASP:Button ID="btnUpdate" runat="server" Text="Insert" CommandName="Insert" />
                <ASP:Button ID="btnCancle" runat="server" Text="Cancle" CommandName="Cancel" />
            </InsertItemTemplate>
            <ItemSeparatorTemplate>
                <div >
                </div>
            </ItemSeparatorTemplate>
            
        </ASP:ListVIEw>

這部分代碼中有個重要的部分就是通過<LayoutTemplate>模板來設置控件的樣式，布局，這也是新增的模板。在VS.Net2008的正式版本中，要正常運行頁面必須在該模板中加入一個名為itemPlaceholder的PlaceHolder控件。要不會出現如下異常：

An item placeholder must be specified on ListView ''ListVIEw1''. Specify an item placeholder by setting a control''s ID property to "itemPlaceholder".

<ItemTemplate>模板用來綁定顯示到頁面上的數據， <EditItemTemplate>用來顯示處於編輯狀態的時候顯示的數據，其他的可以以此類推。

與ListView還搭配的一起使用了新增的DataPager控件，這個主要是用於ListVIEw控件的分頁，是新增的分頁空也，可以方便，高效的進行分頁。

後台代碼：

    string ConStr = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
    protected void Page_Load(object sender, EventArgs e)
    ...{
 &nbsp;      if (!IsPostBack)
        ...{
            ViewState["SupplierID"] = "SupplIErID";
            VIEwState["Direction"] = "DESC";
            BindListVIEw();
        }

    }

    private void BindListVIEw()
    ...{
        string QueryCon = "SELECT SupplierID,CompanyName,ContactName,Address,City FROM SupplIErs";
        SqlConnection NorthWindCon = new SqlConnection(ConStr);
        SqlDataAdapter NorthWindDa = new SqlDataAdapter(QueryCon, ConStr);
        DataSet Ds = new DataSet();
        NorthWindDa.Fill(Ds, "SupplIErs");
        ListView1.DataKeyNames = new string[] ...{ "SupplIErID" };
        DataView Dv = Ds.Tables["Suppliers"].DefaultVIEw;
        //排序表達式
        string SortExpress = (string)ViewState["SupplierID"] + " " + (string)VIEwState["Direction"];
  &nb    Dv.Sort = SortExpress;
        //綁定數據源
        //ListView1.DataSource = Ds.Tables["SupplIErs"];
        ListVIEw1.DataSource = Dv;
        ListVIEw1.DataBind();

    }


    protected void ListView1_ItemEditing(object sender, ListVIEwEditEventArgs e)
    ...{
        ListVIEw1.EditIndex = e.NewEditIndex;
        BindListVIEw();
    }


    protected void ListView1_ItemDataBound(object sender, ListVIEwItemEventArgs e)
    ...{
        if (e.Item.ItemType == ListVIEwItemType.DataItem)
        ...{
            ((Button)e.Item.FindControl("btnDelete")).Attributes["onclick"] = "if(!confirm(''你真的要刪除這條記錄麼?''))return   false;";
        }
        
    }
    protected void ListView1_ItemCanceling(object sender, ListVIEwCancelEventArgs e)
    ...{
        //取消編輯
        if (e.CancelMode == ListVIEwCancelMode.CancelingEdit)
        ...{
            //e.Cancel = true;
            ListVIEw1.EditIndex = -1;
            BindListVIEw();
            ShowMessage("取消編輯");
        }
        else if (e.CancelMode == ListVIEwCancelMode.CancelingInsert)
        ...{
            //BindListVIEw();
            return;
        }


    }


    protected void ListView1_ItemInserting(object sender, ListVIEwInsertEventArgs e)
    ...{
        ((TextBox)ListVIEw1.InsertItem.FindControl("txtMy")).ReadOnly = true;
        string CompanyName = Server.HtmlEncode(((TextBox)ListVIEw1.InsertItem.FindControl("TextBox1")).Text.ToString());
        string ContactName = Server.HtmlEncode(((TextBox)ListVIEw1.InsertItem.FindControl("TextBox2")).Text.ToString());
        string Address = Server.HtmlEncode(((TextBox)ListVIEw1.InsertItem.FindControl("TextBox3")).Text.ToString());
        string City = Server.HtmlEncode(((TextBox)ListVIEw1.InsertItem.FindControl("TextBox4")).Text.ToString());

        string InsertQuery = "INSERT INTO SupplIErs (CompanyName,ContactName,Address,City) VALUES (''" + CompanyName + "'',''" + ContactName + "'',''" + Address + "'',''" + City + "'')";
        SqlConnection InsertCon = new SqlConnection(ConStr);
        SqlCommand InsertCmd = new SqlCommand(InsertQuery, InsertCon);
        try
        ...{
            InsertCon.Open();
            InsertCmd.ExecuteNonQuery();
            BindListVIEw();
            //將插入行顯示到最後
            ListVIEw1.InsertItemPosition = InsertItemPosition.LastItem;

        }
        catch
...{
            ShowMessage("插入新數據出錯，請重新輸入");
        }
        finally
        ...{
            InsertCon.Dispose();
            InsertCmd.Dispose();
        }
    }

    protected void ListView1_ItemUpdating(object sender, ListVIEwUpdateEventArgs e)
    ...{
        string KeyId = ListVIEw1.DataKeys[e.ItemIndex].Value.ToString();
        //找到listvIEw改行的數據集合
        string CompanyName = Server.HtmlEncode(((TextBox)ListVIEw1.Items[e.ItemIndex].FindControl("TextBox1")).Text.ToString());
        string ContactName = Server.HtmlEncode(((TextBox)ListVIEw1.Items[e.ItemIndex].FindControl("TextBox2")).Text.ToString());
        string Address = Server.HtmlEncode(((TextBox)ListVIEw1.Items[e.ItemIndex].FindControl("TextBox3")).Text.ToString());
        string City = Server.HtmlEncode(((TextBox)ListVIEw1.Items[e.ItemIndex].FindControl("TextBox4")).Text.ToString());
        string UpdateStr = "UPDATE SupplIErs SET CompanyName=''" + CompanyName + "'',ContactName=''" + ContactName + "''," +
                            "Address=''" + Address + "'',City=''" + City + " ''WHERE SupplIErID=''" + KeyId + "'' ";
        SqlConnection UpdateCon = new SqlConnection(ConStr);
        SqlCommand UpdateCmd = new SqlCommand(UpdateStr, UpdateCon);
        try
        ...{
            UpdateCon.Open();
            UpdateCmd.ExecuteNonQuery();
            ListVIEw1.EditIndex = -1;
            BindListVIEw();
        }
        catch
        ...{
            ShowMessage("更新出錯，請重新編輯");
        }
        finally
        ...{
            UpdateCon.Dispose();
            UpdateCmd.Dispose();
        }
    }


    protected void ListView1_Sorting(object&nbsp;sender, ListVIEwSortEventArgs e)
    ...{
        if (ViewState["SupplIErID"].ToString() == e.SortExpression)
        ...{
            if (VIEwState["Direction"].ToString() == "DESC")
            ...{
                VIEwState["Direction"] = "ASC";
            }
            else
            ...{
                VIEwState["Direction"] = "DESC";
            }
        }
        else
        ...{
            ViewState["SupplIErID"] = e.SortExpression;
        }
        BindListVIEw();
    }


    private void ShowMessage(string Message)
    ...{
        Literal TxtMsg = new Literal();
        TxtMsg.Text = "<script>alert(''" + Message + "'')</script>";
        Page.Controls.Add(TxtMsg);
    }

    protected void ListView1_ItemDeleting(object sender, ListVIEwDeleteEventArgs e)
    ...{
        string KeyID = ListVIEw1.DataKeys[e.ItemIndex].Value.ToString();
        string DeleteStr = "DELETE FROM Suppliers WHERE SupplIErID=''" + KeyID + "''";
        SqlConnection DeleteCon = new SqlConnection(ConStr);
        SqlCommand DeleteCmd = new SqlCommand(DeleteStr, DeleteCon);
        try
        ...{
            DeleteCon.Open();
            DeleteCmd.ExecuteNonQuery();
            BindListVIEw();
            ShowMessage("刪除成功");
        }
        catch 
        ...{
            ShowMessage("刪除出錯，請檢查數據是否有關聯");
        }
        finally
        ...{
            DeleteCon.Dispose();
            DeleteCmd.Dispose();
        }
    }

以前的edit_cancel事件在ListView控件中為item_cancel，在該事件中可以判斷是取消編輯還是取消插入新的數據。大家可以看代碼。本篇文章主要是對ListVIEw控件一些基本的事件的運用。下一篇會繼續深入的學習該控件。