另一个下拉列表中的下拉列表项 [英] Dropdown list items on another dropdown

问题描述

HI

我的表单中有一个单选按钮(rbn1)和3个下拉列表(国家，州，城市).
如果我选择我的单选按钮，则应启用* country下拉列表，而应该禁用state和city下拉列表，country下拉列表项(印度，美国)

现在，如果我从列表项中选择印度"，那么应该启用状态下拉列表"
和城市下拉菜单应禁用

现在，如果我从列表项中选择"USA"，则应启用城市"下拉列表，而应禁用州"下拉列表.

HI

I am having a radio button(rbn1) and 3 drop down lists(country,state,city) in my form.
if i select my radio button then *country drop down should be enabled and state and city drop down should be disabled the country drop down list items ( India,USA)

Now if i select the India from list item..then state Drop down list should be enabled
and city drop down should be disabled

Now if i select the USA from list item then city Drop down list should be enabled and state drop down should be disabled.

Is it possible?

推荐答案

它称为 Cascading Dropdown .

看这里:
CascadingDropDown演示 [使用SQL数据库的AJAX级联下拉示例 [ ^ ]
在选择ASP.NET上填充级联DropDownList [面向初学者的AJAX(第2部分)-使用XMLHttpRequest和jQuery AJAX实施级联下拉列表 [ ^ ]

It''s called Cascading Dropdown.

Look here:
CascadingDropDown Demonstration[^]
AJAX Cascading Dropdown Example using SQL Database[^]
Populate Cascading DropDownList On Selection ASP.NET[^]

If not update panels, then you need to use traditional AJAX - XMLHttpRequest.
Refer:
AJAX for beginners (Part 2) - Using XMLHttpRequest and jQuery AJAX to implement a cascading dropdown[^]

可以直接通过ASP.NET完成，下面是代码.

This can be done directly through ASP.NET, Below is Code.

protected void ddlCountry_SelectedIndexChanged(object sender, EventArgs e)
    {
        ddlState.DataSource = res.States(Convert.ToInt16(ddlCountry.SelectedValue));
        ddlState.DataTextField = "StateName";
        ddlState.DataValueField = "StateID";
        ddlState.DataBind();
        ddlState.Items.Insert(0, "Select");
        ddlDist.Enabled = false;
        ddlCity.Enabled = false;
    }
    protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
    {
        ddlDist.DataSource = res.Districts(Convert.ToInt16(ddlState.SelectedValue));
        ddlDist.DataTextField = "DistName";
        ddlDist.DataValueField = "DistID";
        ddlDist.DataBind();
        ddlDist.Items.Insert(0, "Select");
        ddlDist.Enabled = true;
        ddlCity.Enabled = false;
    }
    protected void ddlDist_SelectedIndexChanged(object sender, EventArgs e)
    {
        ddlCity.DataSource = res.Cities(Convert.ToInt16(ddlDist.SelectedValue));
        ddlCity.DataTextField = "CityName";
        ddlCity.DataValueField = "CityID";
        ddlCity.DataBind();
        ddlCity.Items.Insert(0, "Select");
        ddlCity.Enabled = true;
    }

此代码的完整概念在此处发布.

http://blog.johnbhatt.com/2012/08/dropdownlist-country- state-district-city.html

您可以使用UpdatePanel从PostBack保存页面.

Full concept of this code is posted here.

http://blog.johnbhatt.com/2012/08/dropdownlist-country-state-district-city.html

you can use UpdatePanel to save page from PostBack.

看看: CP搜索 [ ^ ]

Have a look: c# combobox selectedindexchanged events[^]

..and more similar threads on CP Search[^]

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