扩展(ASP.NET) BoundField

Question

我想创建一个控件来扩展在GridView中使用的BoundField。我想要做的是提供另一个名为HighlightField的属性，该属性类似于DataField属性，因为我想为它命名一个数据列。给定该数据列，它将查看该值是true还是false，并突出显示给定行上给定列中的给定文本。

一些psuedo-code如果这没有意义的话：

<asp:GridView id="grid">
  <Columns>
    <asp:BoundField DataField="Name" />
    <cc:HighlightField DataField="Name" HighlightField="IsHighlighted" />
  </Columns>
</asp:GridView>

然后在数据绑定或其他什么东西中：

if(this row's IsHighlighted value is true)
  set the CssClass of this datacell  = "highlighted"
(or wrap a span tag around the text)

Ravish给我指明了正确的方向，以下是我最终的结论：

public class HighlightedBoundField : BoundField
{
    public string HighlightField
    {
        get { return ViewState["HighlightField"].ToString(); }
        set
        {
            ViewState["HighlightField"] = value;
            OnFieldChanged();
        }
    }

    public override void InitializeCell(DataControlFieldCell cell, DataControlCellType cellType, DataControlRowState rowState, int rowIndex)
    {
        base.InitializeCell(cell, cellType, rowState, rowIndex);

        bool isDataRowAndIsHighlightFieldSpecified = cellType == DataControlCellType.DataCell && !string.IsNullOrEmpty(HighlightField);
        if (isDataRowAndIsHighlightFieldSpecified)
        {
            cell.DataBinding += new EventHandler(cell_DataBinding);
        }
    }

    void cell_DataBinding(object sender, EventArgs e)
    {
        TableCell cell = (TableCell)sender;
        object dataItem = DataBinder.GetDataItem(cell.NamingContainer);
        cell.Text = DataBinder.GetPropertyValue(dataItem, DataField).ToString();

        bool highlightThisCellsText = Convert.ToBoolean(DataBinder.GetPropertyValue(dataItem, HighlightField));
        if (highlightThisCellsText)
        {
            cell.CssClass += " highlight";
        }
    }
}

Answer 1

未经测试：

public class HighlightBoundField : DataControlField {

    //property to indicate if this field should be highlighted, given the value of this property
    //
    public string HighlightField {
        get {
            object value = ViewState["HighlightField"];

            if (value != null) {
                return Convert.ToString(value);
            }

            return "";
        }

        set {
            ViewState["HighlightField"] = value;
            OnFieldChanged();
        }
    }

    //property to display as text in the cell
    //
    public string DataField {
        get {
            object value = ViewState["DataField"];

            if (value != null) {
                return value.ToString();
            }

            return string.Empty;
        }

        set {
            ViewState["DataField"] = value;

            OnFieldChanged();
        }
    }

    //bound field creation
    //
    protected override DataControlField CreateField() {
        return new BoundField();
    }

    //override the method that is used to populate and format a cell
    //
    public override void InitializeCell(DataControlFieldCell cell, DataControlCellType cellType, DataControlRowState rowState, int rowIndex) {
        base.InitializeCell(cell, cellType, rowState, rowIndex);

        //if this celltype is a data row
        //
        if (cellType == DataControlCellType.DataCell && !string.IsNullOrEmpty(HighlightField)) {
            //create label control to display text
            //
            var lblText = new Label();

            //add event listener for when the label is bound
            //
            lblText.DataBinding += new EventHandler(lblText_DataBinding);

            //add label to controls collection
            //
            cell.Controls.Add(lblText);
        }
    }

    void lblText_DataBinding(object sender, EventArgs e) {
        //retrieve data item and set label text
        //
        Label lblText = (Label) sender;
        object dataItem = DataBinder.GetDataItem(lblText.NamingContainer);
        lblText.Text = DataBinder.GetPropertyValue(dataItem, DataField).ToString();

        //check if value should be highlighted
        //
        if (Convert.ToBoolean(DataBinder.GetPropertyValue(dataItem, HighlightField))) {
            lblText.Style.Add("background-color", "yellow");
        }
    }
}