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[英]GridView and CheckBoxList with UpdatePanel in asp.net (C#)
[英]Asp.net updatepanel clears checkboxlist selections
我在Ajax UpdatePanel中有一個ASP.Net CheckBoxList控件。
我將在下面的HTML中隨附代碼(C#)。
我發現CheckBoxList不能通過回發持久化。
順便說一句,這有點混亂。 這是一個原型。
這是用於填充原始CheckBoxList的方法
protected void BindCheckboxes()
{
chkBuildings.Items.Clear();
chkNeighborhoods.Items.Clear();
string city = ddlFindHome_Location.SelectedItem.Value.ToLower();
ResidentDataContext rdc = new ResidentDataContext(Utility.Lookup.GetResidentConnectionString());
var neighs = (from n in rdc.spNeighborhoods where n.vchCity.Equals(city) select n);
foreach (var neighborhood in neighs)
{
ListItem li = new ListItem();
li.Value = neighborhood.intNeighborhoodID.ToString();
li.Attributes["onclick"] = string.Format("document.getElementById('{0}').click();", btnNeighHack.ClientID);
li.Text = neighborhood.vchNeighborhood;
chkNeighborhoods.Items.Add(li);
}
var builds = (from b in rdc.spBuildings
join nb in rdc.spNeighborhoodBuildings on b.intBuildingID equals nb.intBuildingID
join n in rdc.spNeighborhoods on nb.intNeightborhoodID equals n.intNeighborhoodID
where n.vchCity.ToLower().Equals(city)
select b).Distinct();
foreach (var buildings in builds)
{
ListItem li = new ListItem();
li.Value = buildings.intBuildingID.ToString();
li.Text = buildings.vchName;
chkBuildings.Items.Add(li);
}
upNeighs.Update();
upBuilds.Update();
}
BindCheckboxes()從以下位置調用:
protected void ddlFindHome_Location_SelectedIndexChanged(object sender, EventArgs e)
{
BindCheckboxes();
}
這是用於填充另一個CheckBoxList的復選框的回發方法
protected void btnNeighHack_Click(object sender, EventArgs e)
{
List<int> neighs = new List<int>();
foreach (ListItem li in chkNeighborhoods.Items)
{
if (li.Selected)
neighs.Add(Convert.ToInt32(li.Value));
}
ResidentDataContext rdc = new ResidentDataContext(Utility.Lookup.GetResidentConnectionString());
var builds = (from b in rdc.spBuildings
join nb in rdc.spNeighborhoodBuildings on b.intBuildingID equals nb.intBuildingID
where neighs.Contains(nb.intNeightborhoodID)
select b.intBuildingID).Distinct();
foreach (ListItem li in chkBuildings.Items)
{
li.Selected = false;
}
foreach (ListItem li in chkBuildings.Items)
{
if (builds.Contains(Convert.ToInt32(li.Value)))
li.Selected = true;
}
upBuilds.Update();
}
這是ASP.Net HTML
<asp:UpdatePanel ID="upNeighs" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<div style="font-weight: bold;">
Neighborhood
</div>
<div style="padding-top: 7px; padding-left: 3px;">
<input type="checkbox" id="chkNeighborhood_CheckAll" />Select All
</div>
<hr />
<div>
<asp:CheckBoxList ID="chkNeighborhoods" runat="server" />
<asp:Button style="display: none;" ID="btnNeighHack" runat="server"
onclick="btnNeighHack_Click" />
</div>
</ContentTemplate>
</asp:UpdatePanel>
<asp:UpdatePanel ID="upBuilds" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<div style="padding-left: 6px; padding-top: 5px; font-weight: bold;">
Building
</div>
<div>
<asp:CheckBoxList ID="chkBuildings" runat="server" />
</div>
</ContentTemplate>
</asp:UpdatePanel>
我應該提到過,bindcheckboxes()函數是從
protected void ddlFindHome_Location_SelectedIndexChanged(object sender, EventArgs e)
{
BindCheckboxes();
}
因此,它始終是PostBack。 但我認為您可能對此有所了解。
protected void BindCheckboxes()
{
if(!IsPostBack)
{
chkBuildings.Items.Clear();
chkNeighborhoods.Items.Clear();
string city = ddlFindHome_Location.SelectedItem.Value.ToLower();
ResidentDataContext rdc = new ResidentDataContext(Utility.Lookup.GetResidentConnectionString());
var neighs = (from n in rdc.spNeighborhoods where n.vchCity.Equals(city) select n);
foreach (var neighborhood in neighs)
{
ListItem li = new ListItem();
li.Value = neighborhood.intNeighborhoodID.ToString();
li.Attributes["onclick"] = string.Format("document.getElementById('{0}').click();", btnNeighHack.ClientID);
li.Text = neighborhood.vchNeighborhood;
chkNeighborhoods.Items.Add(li);
}
var builds = (from b in rdc.spBuildings
join nb in rdc.spNeighborhoodBuildings on b.intBuildingID equals nb.intBuildingID
join n in rdc.spNeighborhoods on nb.intNeightborhoodID equals n.intNeighborhoodID
where n.vchCity.ToLower().Equals(city)
select b).Distinct();
foreach (var buildings in builds)
{
ListItem li = new ListItem();
li.Value = buildings.intBuildingID.ToString();
li.Text = buildings.vchName;
chkBuildings.Items.Add(li);
}
upNeighs.Update();
upBuilds.Update();
}
}
試試看。
好吧,如果您每次更改選擇都清除CheckBoxList,它也會清除您選擇的項目。 我將改為在page_load加載項目。
經過進一步研究,我發現控件在回發過程中並沒有持久存在,並且退出了視圖狀態。 因此,每次回發時,都會從以下位置返回一個空對象:
protected Control PostBackControl
{
get { return Page.FindControl(Request.Params.Get("__EVENTTARGET")); }
}
但它發現下拉列表的值不是默認值,並開始重新綁定所有內容。
當我僅在PostBackControl是下拉列表時綁定復選框列表時,控件將永遠不會綁定,因為更新面板中的所有內容都超出了范圍。
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