自己好几个地方要用到联动控件,项目又不想用Ajax,又想在客户端实现联动而不刷新,还想在服务器端用相似的代码来绑定项,还想在服务器端用相同的代码得到选定的值(也就是值可以提交),想了想,还是写一个控件好了.
以国家,省,市举例,我的实现思路是,
1.把所有国家绑定到国家列表,把所有的省绑定在省列表(包括各各国家),把所以的市绑定在市列表(包括所有的市).
2. 在客户端,用脚本把省,市和各项分组并保存,然后从 select.options 里去除不需要的option.
修正不能在同页面有多个联动的BUG
代码如下:
1. 控件代码:
namespace Iyond.Web.UI.WebControls
{
public class RelationDropDownList : System.Web.UI.WebControls.DropDownList
{
protected ValueParentValueDictionary valueParentValues = new ValueParentValueDictionary();
[DescriptionAttribute("ParentDropDownListControl"), IDReferenceProperty, TypeConverter(typeof(RelationDropDownListControlConverter)), Themeable(false), DefaultValue(""), CategoryAttribute("Behavior")]
public string ParentDropDownListControl
{
get
{
object obj1 = this.ViewState["ParentDropDownListControl"];
if (obj1 != null)
{
return (string)obj1;
}
return string.Empty;
}
set
{
this.ViewState["ParentDropDownListControl"] = value;
}
}
[DescriptionAttribute("ParentDropDownListControl"), IDReferenceProperty, TypeConverter(typeof(RelationDropDownListControlConverter)), Themeable(false), DefaultValue(""), CategoryAttribute("Behavior")]
public string ChildDropDownListControl
{
get
{
object obj1 = this.ViewState["ChildDropDownListControl"];
if (obj1 != null)
{
return (string)obj1;
}
return string.Empty;
}
set
{
this.ViewState["ChildDropDownListControl"] = value;
}
}
[DescriptionAttribute("DataParentValueField"), Themeable(false), DefaultValue(""), CategoryAttribute("Data")]
public virtual string DataParentValueField
{
get
{
object obj2 = this.ViewState["ParentDataValueField"];
if (obj2 != null)
{
return (string)obj2;
}
return string.Empty;
}
set
{
this.ViewState["ParentDataValueField"] = value;
if (base.Initialized)
{
base.RequiresDataBinding = true;
}
}
}
protected RelationDropDownList ParentDropDownList
{
get
{
if (string.IsNullOrEmpty(this.ParentDropDownListControl))
return null;
return this.NamingContainer.FindControl(this.ParentDropDownListControl) as RelationDropDownList;
}
}
protected RelationDropDownList ChildDropDownList
{
get
{
if (string.IsNullOrEmpty(this.ChildDropDownListControl))
return null;
return this.NamingContainer.FindControl(this.ChildDropDownListControl) as RelationDropDownList;
}
}
protected override void Render(HtmlTextWriter writer)
{
base.Render(writer);
if (this.ChildDropDownList == null)
{
//这是最后一级,依本身的SelectedIndex 来更新上级 修正不能在同页面有多个联动的BUG
Page.ClientScript.RegisterStartupScript(this.GetType(), this.ClientID + "_relddl_clearUp", string.Format("javascript:relddl_clearUp('{0}');", this.ClientID),true);
}
}
protected override void OnPreRender(EventArgs e)
{
Page.ClientScript.RegisterClientScriptResource(typeof(RelactionDropDownList), "Iyond.Web.UI.WebControls.DropDownList.Resources.RelationDDL.js");
base.OnPreRender(e);
}
protected override void AddAttributesToRender(HtmlTextWriter writer)
{
base.AutoPostBack = false;
base.AddAttributesToRender(writer);
writer.AddAttribute("parentSelect", this.ParentDropDownList != null?this.ParentDropDownList.ClientID:"");
writer.AddAttribute("childSelect",this.ChildDropDownList != null?this.ChildDropDownList.ClientID: "");
writer.AddAttribute( HtmlTextWriterAttribute.Onchange, "javascript:relddl_onchange(this,event)");
}
protected override void PerformDataBinding(System.Collections.IEnumerable dataSource)
{
base.PerformDataBinding(dataSource);
if (this.ParentDropDownList != null)
{
valueParentValues.Clear();
foreach (object obj in dataSource)
{
string dataValueField = this.DataValueField;
string parentDataValueField = this.DataParentValueField;
string value = Convert.ToString(DataBinder.GetPropertyValue(obj, dataValueField));
if (valueParentValues.ContainsKey(value))
{
throw new ArgumentException("相关的列表中. DataValueField 字段的值不能重复");
}
string parentValue = Convert.ToString(DataBinder.GetPropertyValue(obj, parentDataValueField));
valueParentValues.Add(value, parentValue);
}
SetItemParentValue();
}
}
protected virtual void SetItemParentValue()
{
foreach (string value in valueParentValues.Keys)
{
string parentValue = valueParentValues[value];
ListItem lt = this.Items.FindByValue(value);
if (lt != null)
{
lt.Attributes["parentValue"] =parentValue;
}
}
}
protected override object SaveViewState()
{
object x = base.SaveViewState();
object y = valueParentValues;
object z = null;
if (((z == null) && (y == null)))
{
return null;
}
return new Triplet(x, y, z);
}
protected override void LoadViewState(object savedState)
{
if (savedState != null)
{
Triplet triplet = (Triplet)savedState;
base.LoadViewState(triplet.First);
valueParentValues = triplet.Second as ValueParentValueDictionary;
if (valueParentValues != null)
{
SetItemParentValue();
}
}
else
{
base.LoadViewState(null);
}
}
}
public class RelationDropDownListControlConverter : ControlIDConverter
{
protected override bool FilterControl(Control control)
{
if (control is RelationDropDownList)
return true;
else
{
return false;
}
}
}
[Serializable]
public class ValueParentValueDictionary : Dictionary<string, string>
{
public ValueParentValueDictionary()
:base()
{}
public ValueParentValueDictionary(IDictionary<string, string> dictionary)
:base(dictionary)
{}
public ValueParentValueDictionary(IEqualityComparer<string> comparer)
:base(comparer)
{}
public ValueParentValueDictionary(int capacity)
:base(capacity)
{}
public ValueParentValueDictionary(IDictionary<string, string> dictionary, IEqualityComparer<string> comparer)
:base(dictionary,comparer)
{}
public ValueParentValueDictionary(int capacity, IEqualityComparer<string> comparer)
:base(capacity,comparer)
{}
protected ValueParentValueDictionary(SerializationInfo info, StreamingContext context)
:base(info,context)
{}
}
}
2. 使用举例:
<iyond:RelationDropDownList ID="ddlCountry" runat="server" ChildDropDownListControl="ddlProvince">
</iyond:RelationDropDownList>
<iyond:RelationDropDownList ID="ddlProvince" runat="server" ChildDropDownListControl="ddlCity" ParentDropDownListControl="ddlCountry">
</iyond:RelationDropDownList>
<iyond:RelationDropDownList ID="ddlCity" runat="server" ParentDropDownListControl="ddlProvince">
</iyond:RelationDropDownList>
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
List<ZoneItem> listCountry = new List<ZoneItem>(