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]
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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);
}

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]
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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++;
}

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]
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/// <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());
}
}

/// <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。