DevExpress ASPxGridView 使用文档五：事件

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-- ASPxGridView 事件
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ASPxGridView
    默认是以callback方式（ajax方式）传递数据给服务器来实现局部刷新功能的
    若要改为postback方式，可设置 EnableCallBacks = "false"

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展示视图
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RowCreated（创建行数据时触发，类似 GridView 的 DataItemCreate 事件）
    protected void grid_HtmlRowCreated(object sender, DevExpress.Web.ASPxGridView.ASPxGridViewTableRowEventArgs e) 
    {
        if(e.RowType != DevExpress.Web.ASPxGridView.GridViewRowType.Data) return;
        // 设置模板列lable控件值
        Label label = grid.FindRowCellTemplateControl(e.VisibleIndex, null, "changePercent") as Label;
        decimal change = (decimal)grid.GetRowValues(e.VisibleIndex, "Change");
        label.Text = string.Format("{0:p}", change);
        // 设置模板列image控件的图像
        System.Web.UI.WebControls.Image img = (System.Web.UI.WebControls.Image)grid.FindRowCellTemplateControl(e.VisibleIndex, null, "changeImage");
        img.Visible = false;
        if(change != 0) {
            img.Visible = true;
            img.ImageUrl = change < 0 ? "~/Images/arRed.gif" : "~/Images/arGreen.gif";
            label.ForeColor = change < 0 ? Color.Red : Color.Green;
        }
    }

HtmlRowPrepared（行准备？可在此设置行的展示效果，如背景）
    protected void grid_HtmlRowPrepared(object sender, ASPxGridViewTableRowEventArgs e) 
    {
        bool hasError = e.GetValue("FirstName").ToString().Length <= 1;
        hasError = hasError || e.GetValue("LastName").ToString().Length <= 1;
        hasError = hasError || !e.GetValue("Email").ToString().Contains("@");
        hasError = hasError || (int)e.GetValue("Age") < 18;
        DateTime arrival = (DateTime)e.GetValue("ArrivalDate");
        hasError = hasError || DateTime.Today.Year != arrival.Year || DateTime.Today.Month != arrival.Month;
        if(hasError) {
            e.Row.ForeColor = System.Drawing.Color.Red;
        }
    }

UnboundColumnData （非绑定列数据填充）
    protected void grid_CustomUnboundColumnData(object sender, DevExpress.Web.ASPxGridView.ASPxGridViewColumnDataEventArgs e) 
    {
        if(e.Column.FieldName == "Total") 
        {
            decimal price = (decimal)e.GetListSourceFieldValue("UnitPrice");
            int quantity = Convert.ToInt32(e.GetListSourceFieldValue("Quantity"));
            e.Value = price * quantity;
        }
    }

CustomColumnDisplayText（定制列文本展示）
     protected void grid_CustomColumnDisplayText(object sender, DevExpress.Web.ASPxGridView.ASPxGridViewColumnDisplayTextEventArgs e) 
     {
         if(object.Equals(e.Column, grid.Columns["Size"]))
             e.DisplayText = GetSizeDisplayText(e.Value);
     }

SummaryDisplayText（合计行文本展示）
     protected void grid_SummaryDisplayText(object sender, DevExpress.Web.ASPxGridView.ASPxGridViewSummaryDisplayTextEventArgs e) {
         if(e.Item.FieldName == "Size") {
             e.Text = GetSizeDisplayText(e.Value);
         }
     }

HeaderFilterFillItems（自定义过滤器处理逻辑）
    protected void grid_HeaderFilterFillItems(object sender, ASPxGridViewHeaderFilterEventArgs e) 
    {
        if(object.Equals(e.Column, grid.Columns["Total"])) {
            PrepareTotalFilterItems(e);
            return;
        }
        if(object.Equals(e.Column, grid.Columns["Quantity"])) {
            PrepareQuantityFilterItems(e);
            return;
        }
    }

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回调处理
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CustomCallback（Ajax 回调处理）
    <select id="selGridLayout" onchange="grid.PerformCallback(this.value);" >
        <option selected="selected" value="0">Country</option>
        <option value="1">Country, City</option>
        <option value="2">Company Name</option>
    </select>
    protected void grid_CustomCallback(object sender, ASPxGridViewCustomCallbackEventArgs e) 
    {
        int layoutIndex = -1;
        if(int.TryParse(e.Parameters, out layoutIndex))
            ApplyLayout(layoutIndex); // 更换布局
    }

CustomButtonCallback（定制按钮的ajax回调处理）
    protected void grid_CustomButtonCallback(object sender, ASPxGridViewCustomButtonCallbackEventArgs e) 
    {
        if(e.ButtonID != "Copy") return;
        copiedValues = new Hashtable();
        foreach(string fieldName in copiedFields) 
            copiedValues[fieldName] = grid.GetRowValues(e.VisibleIndex, fieldName);
        
        grid.AddNewRow();
    }

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编辑视图
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InitNewRow（新建行的数据初始化处理）
    protected void grid_InitNewRow(object sender, DevExpress.Web.Data.ASPxDataInitNewRowEventArgs e) 
    {
        if(copiedValues == null) return;
        foreach(string fieldName in copiedFields) {
            e.NewValues[fieldName] = copiedValues[fieldName];
        }
    }

CellEditorInitialize（编辑器初始化）
    protected void grid_CellEditorInitialize(object sender, ASPxGridViewEditorEventArgs e) 
    {
        if(grid.IsEditing && !grid.IsNewRowEditing && e.Column.FieldName == "City")
        {
            string country = (string)grid.GetRowValuesByKeyValue(e.KeyValue, "Country");
            ASPxComboBox combo = e.Editor as ASPxComboBox;
            FillCityCombo(combo, country);
            combo.Callback += new CallbackEventHandlerBase(cmbCity_OnCallback);
        }
    }

StartRowEditing（开始编辑）
    protected void grid_StartRowEditing(object sender, DevExpress.Web.Data.ASPxStartRowEditingEventArgs e) 
    {
        if(!grid.IsNewRowEditing) {
            grid.DoRowValidation();
        }
    }

RowValidating （行数据验证）
    protected void grid_RowValidating(object sender, DevExpress.Web.Data.ASPxDataValidationEventArgs e) 
    {
        foreach(GridViewColumn column in grid.Columns) {
            GridViewDataColumn dataColumn = column as GridViewDataColumn;
            if(dataColumn == null) continue;
            if(e.NewValues[dataColumn.FieldName] == null) {
                e.Errors[dataColumn] = "Value can't be null.";
            }
        }
        if(e.Errors.Count > 0) e.RowError = "Please, fill all fields.";
        if(e.NewValues["FirstName"] != null && e.NewValues["FirstName"].ToString().Length < 2) {
            AddError(e.Errors, grid.Columns["FirstName"], "First Name must be at least two characters long.");
        }
        if(e.NewValues["LastName"] != null && e.NewValues["LastName"].ToString().Length < 2) {
            AddError(e.Errors, grid.Columns["LastName"], "Last Name must be at least two characters long.");
        }
        if(e.NewValues["Email"] != null && !e.NewValues["Email"].ToString().Contains("@")) {
            AddError(e.Errors, grid.Columns["Email"], "Invalid e-mail.");
        }

        int age = 0;
        int.TryParse(e.NewValues["Age"] == null ? string.Empty : e.NewValues["Age"].ToString(), out age);
        if(age < 18) {
            AddError(e.Errors, grid.Columns["Age"],  "Age must be greater than or equal 18.");
        }
        DateTime arrival = DateTime.MinValue;
        DateTime.TryParse(e.NewValues["ArrivalDate"] == null ? string.Empty : e.NewValues["ArrivalDate"].ToString(), out arrival);
        if(DateTime.Today.Year != arrival.Year || DateTime.Today.Month != arrival.Month) {
            AddError(e.Errors, grid.Columns["ArrivalDate"], "Arrival date is required and must belong to the current month.");
        }

        if(string.IsNullOrEmpty(e.RowError) && e.Errors.Count > 0) e.RowError = "Please, correct all errors.";
    }