关于ExtAspNet的Grid的动态增加列的方法

动态列 ExtAspNet.BoundField  只能在Page_Init和Page_Load等方法中增加，而在有些地方，比如点击按钮后动态增加，就无法生效。
有个场景：查询时，用户选择需要的字段来显示，就涉及到动态列。
方法一：规避解决，查询结果直接弹出个页面，没有问题。

方法二：

(1) 在Page_Load方法中增加若干个隐藏列

[html] view plaincopyprint?

1. for (int i = 0; i < QUERY_GRIDVIEW_COLUMN_COUNT; i++)  
2.             {  
3.                 ExtAspNet.BoundField boundField = new ExtAspNet.BoundField();  
4.                 boundField.HeaderText = string.Format("第{0}列", i + 1);  
5.                 boundField.Hidden = true;  
6.                 gridQueryResult.Columns.Add(boundField);  
7.             }  

for (int i = 0; i < QUERY_GRIDVIEW_COLUMN_COUNT; i++)            {                ExtAspNet.BoundField boundField = new ExtAspNet.BoundField();                boundField.HeaderText = string.Format("第{0}列", i + 1);                boundField.Hidden = true;                gridQueryResult.Columns.Add(boundField);            }

(2) 在查询过程中设置绑定列对于的字段

/* 获得查询结果 */

DataSet ds = ....

[csharp] view plaincopyprint?

1. foreach (DataColumn dataColumn in ds.Tables[0].Columns)  
2.                 {  
3.                     if (dataKeyNames.Contains(dataColumn.ColumnName))  
4.                     {  
5.                         continue;  
6.                     }  
7.                     ExtAspNet.BoundField boundField = (ExtAspNet.BoundField)gridQueryResult.Columns[index];  
8.                     if (!dataKeyNames.Contains(dataColumn.ColumnName))  
9.                     {  
10.                         boundField.Hidden = false;  
11.                     }  
12.                     boundField.DataTooltipField = dataColumn.ColumnName;                      
13.                     boundField.DataField = dataColumn.ColumnName;                      
14.                     //boundField.HeaderText = dataColumn.Caption;  
15.                     index++;  
16. }  

foreach (DataColumn dataColumn in ds.Tables[0].Columns)                {                    if (dataKeyNames.Contains(dataColumn.ColumnName))                    {                        continue;                    }                    ExtAspNet.BoundField boundField = (ExtAspNet.BoundField)gridQueryResult.Columns[index];                    if (!dataKeyNames.Contains(dataColumn.ColumnName))                    {                        boundField.Hidden = false;                    }                    boundField.DataTooltipField = dataColumn.ColumnName;                                        boundField.DataField = dataColumn.ColumnName;                                        //boundField.HeaderText = dataColumn.Caption;                    index++;}

注意，这里直接设置绑定列 HeaderText 无法生效。

(3)在查询后重新设置标题列

[csharp] view plaincopyprint?

1. /// <summary>   
2.         /// 查询   
3.         /// </summary>   
4.         /// <param name="sender"></param>   
5.         /// <param name="e"></param>  
6.         protected void btnQuery_Click(object sender, EventArgs e)  
7.         {  
8.             gridQueryResult.PageIndex = 0;  
9.             LoadData();  
10.             if (DataFieldTable != null)  
11.             {  
12.                 StringBuilder sb = new StringBuilder();  
13.                 sb.AppendFormat(@"var grid = Ext.getCmp('{0}'); var columnModel = grid.getColumnModel();", gridQueryResult.ClientID);  
14.                 for (int i = 0; i < DataFieldTable.Rows.Count; i++)  
15.                 {  
16.                     sb.AppendFormat("columnModel.setColumnHeader({0}, '{1}');", i + 1, DataFieldTable.Rows[i]["Alias"]);  
17.                 }  
18.                 ExtAspNet.PageContext.RegisterStartupScript(sb.ToString());  
19.             }  
20.         }  

/// <summary>        /// 查询        /// </summary>        /// <param name="sender"></param>        /// <param name="e"></param>        protected void btnQuery_Click(object sender, EventArgs e)        {            gridQueryResult.PageIndex = 0;            LoadData();            if (DataFieldTable != null)            {                StringBuilder sb = new StringBuilder();                sb.AppendFormat(@"var grid = Ext.getCmp('{0}'); var columnModel = grid.getColumnModel();", gridQueryResult.ClientID);                for (int i = 0; i < DataFieldTable.Rows.Count; i++)                {                    sb.AppendFormat("columnModel.setColumnHeader({0}, '{1}');", i + 1, DataFieldTable.Rows[i]["Alias"]);                }                ExtAspNet.PageContext.RegisterStartupScript(sb.ToString());            }        }

这里用了一个datatable来保存用户选择的字段设置条件等属性，你可以换成你保存用户选择字段列表。