twoleveldropdownlist.cs

x2webcontrols

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data;
using System.Text;

namespace X2Design.UI
{
	/// <summary>
	/// 提供两层菜单的联动，联动逻辑在客户端用Javascript实现，不会出现回传现象。
	/// 当前缺点：若产生两个同样的联动菜单，则客户端代码会产生两份冗余。但不会冲突，可正常使用。
	/// </summary>
	public class TwoLevelDropDownList:Control
	{
		/// <summary>
		/// 主下拉框。
		/// </summary>
		protected System.Web.UI.WebControls.DropDownList ddl1;
		/// <summary>
		/// 从下拉框。
		/// </summary>
		protected System.Web.UI.WebControls.DropDownList ddl2;
		/// <summary>
		/// 
		/// </summary>
		protected DataTable dt1;
		/// <summary>
		/// 
		/// </summary>
		protected DataTable dt2;

		/// <summary>
		/// 获取或者设置数据源。
		/// </summary>
		public virtual DataTable DataSource
		{
			get
			{
				DataTable d=(DataTable)ViewState["DataSource"];
				return d;
			}
			set
			{
				ViewState["DataSource"]=value;
			}
		}

		/// <summary>
		/// 获取或者设置显示的文字字段
		/// </summary>
		public virtual string DataTextField
		{
			get
			{
				string s=(string)ViewState["DataTextField"];
				return (s==null)?String.Empty:s;
			}
			set
			{
				ViewState["DataTextField"]=value;
			}
		}

		/// <summary>
		/// 获取或者设置值字段。
		/// </summary>
		public virtual string DataValueField
		{
			get
			{
				string s=(string)ViewState["DataValueField"];
				return (s==null)?String.Empty:s;
			}
			set
			{
				ViewState["DataValueField"]=value;
			}
		}

		/// <summary>
		/// 获取或者设置从下拉框的主键字段名称，对应于主下拉框的主键字段。
		/// </summary>
		public virtual string SecondKeyField
		{
			get
			{
				string s=(string)ViewState["SecondKeyField"];
				return (s==null)?String.Empty:s;
			}
			set
			{
				ViewState["SecondKeyField"]=value;
			}
		}

		/// <summary>
		/// 获取或设置选项的层次（1表示主下拉框，2表示从下拉框）。
		/// </summary>
		public virtual string LevelField
		{
			get
			{
				string s=(string)ViewState["LevelField"];
				return (s==null)?String.Empty:s;
			}
			set
			{
				ViewState["LevelField"]=value;
			}
		}

		/// <summary>
		/// 主下拉框的标题
		/// </summary>
		public virtual string FirstTitle
		{
			get
			{
				string s=(string)ViewState["FirstTitle"];
				return (s==null)?String.Empty:s;
			}
			set
			{
				ViewState["FirstTitle"]=value;
			}
		}
		/// <summary>
		/// 从下拉框的标题
		/// </summary>
		public virtual string SecondTitle
		{
			get
			{
				string s=(string)ViewState["SecondTitle"];
				return (s==null)?String.Empty:s;
			}
			set
			{
				ViewState["SecondTitle"]=value;
			}
		}
		/// <summary>
		/// 获取或者设置主下拉框的值。对应于下拉框的值字段。
		/// </summary>
		public virtual string FirstValue
		{
			get
			{
				if(this.Page.IsPostBack)
				{
					return this.Page.Request.Form[ddl1.ClientID].ToString();
				}
				string s=(string)ViewState["FirstValue"];
				return (s==null)?"0":s;
			}
			set
			{
				ViewState["FirstValue"]=value;
			}
		}

		/// <summary>
		/// 获取或者设置从下拉框的值。对应于下拉框的值字段。
		/// </summary>
		public virtual string SecondValue
		{
			get
			{
				if(this.Page.IsPostBack)
				{
					return this.Page.Request.Form[ddl2.ClientID].ToString();
				}
				string s=(string)ViewState["SecondValue"];
				return (s==null)?"0":s;
			}
			set
			{
				ViewState["SecondValue"]=value;
			}
		}
		/// <summary>
		/// 产生客户端脚本。
		/// </summary>
		/// <param name="htw">HtmlTextWriter。用于写文件。</param>
		protected void GenInitScript(HtmlTextWriter htw)
		{
			//根据第一个选项值生成第二个下拉框所有选项的脚本
			htw.Write("<script language=javascript>");
			htw.Write("GetOptions_");
			htw.Write(this.ID);
			htw.Write("(\"");
			htw.Write(this.FirstValue);
			htw.Write("\",document.getElementById(\"");
			htw.Write(ddl2.ClientID);
			htw.Write("\"));\n");


			//根据第二个下拉框指定值生成选中的脚本
			htw.Write("SetTheOther_"+this.ID+"(document.getElementById(\"");
			htw.Write(ddl2.ClientID);
			htw.Write("\"),\"");
			htw.Write(this.SecondValue);
			htw.Write("\");\n");
			htw.Write("</script>");
		}


		/// <summary>
		/// 产生级联菜单的客户端脚本。
		/// </summary>
		/// <param name="htw">HtmlTextWriter。用于写文件。</param>
		protected void GenClientScript(HtmlTextWriter htw)
		{
			//StringBuilder sbScript=new StringBuilder();
			htw.Write("<script language=javascript><!--\n");

			//获得下拉框二的选项
			htw.Write("function GetOptions_"	+	this.ID		+	"(value1,ddl2)\n");
			htw.Write("{\n");
			htw.Write("	switch(value1)\n");
			htw.Write("	{\n");
			for(int i=0;i<dt1.Rows.Count;i++)
			{	
				htw.Write("		case \"");
				htw.Write(dt1.Rows[i][this.DataValueField].ToString());
				htw.Write("\":\n");
				htw.Write("			var	OptionArray=new Array(");
				for(int j=0;j<dt2.Rows.Count;j++)
				{
					if(dt2.Rows[j][this.SecondKeyField].ToString()==dt1.Rows[i][this.DataValueField].ToString())
					{
						htw.Write("\"");
						htw.Write(dt2.Rows[j][this.DataTextField].ToString());
						htw.Write("\",");

						htw.Write("\"");
						htw.Write(dt2.Rows[j][this.DataValueField].ToString());
						htw.Write("\",\n");
					}
				}
				
				htw.Write("\"0\",\"0\");\n");
				htw.Write("			break;\n");
			}
			htw.Write("default:\n		var OptionArray=new Array(\"0\",\"0\");\nbreak;");
			htw.Write("}\n");
			htw.Write("ClearDdl_"+this.ID+"(ddl2);\n");
			htw.Write("var x=0;\n");
			htw.Write("for(var i=0;i<OptionArray.length-2;i=i+2)\n{\nx++;\n");
			htw.Write("ddl2.options[x]=new Option(OptionArray[i],OptionArray[i+1]);\n}\n}\n");
			
			//以下函数仅需出现一次
			
				//设置第二个下拉框的选项
				htw.Write("function SetTheOther_"+this.ID+"(ddl2,value2)\n");
				htw.Write("{\n");
				htw.Write("for(var i=0;i<ddl2.options.length;i++)\n");
				htw.Write("{\n");
				htw.Write("	if(ddl2.options[i].value==value2)\n");
				htw.Write("	{\n");
				htw.Write("		ddl2.options[i].selected=true;\n");
				htw.Write("		break;\n");
				htw.Write("	}\n}\n}\n");

				//清空下拉框
				htw.Write("function ClearDdl_"+this.ID+"(ddl){\n");
				htw.Write("for(var i=1;i<ddl.options.length;i++){ddl.options[i]=null;}}\n");
			

			htw.Write("--></script>");
		}

		/// <summary>
		/// 构造函数。
		/// </summary>
		public TwoLevelDropDownList()
		{
			this.PreRender+=new EventHandler(this.RelationDropDownList_PreRender);	
			this.Init+=new EventHandler(RelationDropDownList_Init);
		}
		
	
		/// <summary>
		/// 生成控件。覆盖基类的Render方法。
		/// </summary>
		/// <param name="htw">HtmlTextWriter。用于写文件。</param>
		protected override void Render(HtmlTextWriter htw)
		{
			this.GenClientScript(htw);
			ddl1.RenderControl(htw);
			ddl2.RenderControl(htw);

			//产生进行预处理的客户端脚本
			this.GenInitScript(htw);
		}

		/// <summary>
		/// 绑定数据源，触发绑定事件。
		/// </summary>
		public override void DataBind()
		{
			base.OnDataBinding(EventArgs.Empty);
		}
		/// <summary>
		/// 自定义的绑定逻辑。
		/// </summary>
		protected  void MyBind()
		{	
			dt1=this.DataSource.Copy();
			dt2=dt1.Clone();
			//将两级目录分开到两个数据表中
			for(int i=0;i<dt1.Rows.Count;i++)
			{
				DataRow dr1=dt1.Rows[i];
				if(dr1[this.LevelField].ToString()!="0")
				{
					DataRow dr2=dt2.NewRow();
					for(int j=0;j<dt2.Columns.Count;j++)
					{
						dr2[j]=dr1[j];
					}
					dt2.Rows.Add(dr2);
					dt1.Rows.Remove(dr1);
					i--;
				}
			}

			ddl1.DataSource=dt1;
			ddl1.DataTextField=this.DataTextField;
			ddl1.DataValueField=this.DataValueField;
			ddl1.DataBind();
		}

		/// <summary>
		/// 在调用前产生客户端脚本否则不能获得下拉框客户端id。
		/// </summary>
		/// <param name="sender">事件源。</param>
		/// <param name="e">事件参数。</param>
		private void RelationDropDownList_PreRender(object sender, EventArgs e)
		{
			this.MyBind();
			this.SetTitle();
			//设置下拉框一的选项
			ddl1.ClearSelection();
			ListItem li0=ddl1.Items.FindByValue(this.FirstValue);
			if(li0!=null)
			{
				li0.Selected=true;
			}
			else
			{
				throw new ArgumentException("The value doesn't exist!");
			}

			ddl1.Attributes.Add("OnChange","GetOptions_"+this.ID+"(this.options[this.selectedIndex].value," + ddl2.ClientID + ");");
		}


		/// <summary>
		/// 根据指定的主从下拉框标题产生下拉框。
		/// </summary>
		protected void SetTitle()
		{
			ddl1.Items.Insert(0,new ListItem(this.FirstTitle,"0"));
			ddl2.Items.Insert(0,new ListItem(this.SecondTitle,"0"));
		}

		/// <summary>
		/// 控件初始化时执行
		/// </summary>
		/// <param name="sender">事件源。</param>
		/// <param name="e">事件参数。</param>
		private void RelationDropDownList_Init(object sender, EventArgs e)
		{
			this.Controls.Clear();
			ddl1=new DropDownList();
			ddl2=new DropDownList();
			ddl1.EnableViewState=false;
			ddl2.EnableViewState=false;
			//初始化唯一名字
			ddl1.ID="x2ddl11_"+this.ID;
			ddl2.ID="x2dd1l2_"+this.ID;
			//当页面回传时得到两个选中的个值
			if(this.Page.IsPostBack)
			{
				FirstValue=this.Page.Request.Form[ddl1.ClientID].ToString();
				SecondValue=this.Page.Request.Form[ddl2.ClientID].ToString();
			}
		}
	}
}