ASP.NET Expand/Contract DataGrid

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• Download demo project - 20.5 Kb

Introduction

The ASP.NET DataGrid is very powerful and robust. However, some of the things we need it to do require lots of custom code. Denis Bauer's HierarGrid is an example of a very sophisticated datagrid. Unfortunately, my project needed the ability to expand and contract DataGrid columns rather than DataGrid rows, so I implemented the ExDataGrid server control which is described in this article. Much of the code logic was borrowed from HierarGrid.

You can check out the HierarGrid here.

You can also check out a live demo of ExDataGrid here.

Figure 1. Contracted Columns

Figure 2. Expanded Columns

Using the server control

The ExDataGrid server control requires the use of three classes:

• ExDataGrid - Main server control. This is directly derived from DataGrid and has all functionality of a regular datagrid.
• ExColumnExpand - Column with a plus and minus image. This control is derived from BoundColumn.
• ExColumn - Columns that will contract/expand. This control is derived from BoundColumn and has added properties such as DrawBorders, ForeColor, and BackColor.

To associate the ExColumnExpand and ExColumn classes so that they work together, the property ExGroupName must be assigned for each expansion group.

Example:

<cc1:ExDataGrid id="DataGridReport1" runat="server" 
             BorderColor="#000066" CellPadding="1" BorderWidth="2px"
    AutoGenerateColumns="False" ShowFooter="True">
    <EditItemStyle ForeColor="Black" BackColor="Yellow"></EditItemStyle>
    <AlternatingItemStyle Font-Size="X-Small" BackColor="Gainsboro">
    </AlternatingItemStyle>
    <ItemStyle Font-Size="X-Small" Font-Names="Verdana"></ItemStyle>
    <HeaderStyle Font-Bold="True" BackColor="#D7D7D7"></HeaderStyle>
    <FooterStyle Font-Size="Small" BackColor="RoyalBlue"></FooterStyle>
    <Columns>
        <asp:BoundColumn DataField="Title_ID" HeaderText="Title_ID" 
                         SortExpression="Title_ID"></asp:BoundColumn>
        <cc1:ExColumnExpand ExGroupName="TitleExpand"  DataField="Title" 
                         HeaderText="Title" SortExpression="Title" />
        <cc1:ExColumn DataField="Price" ExGroupName="TitleExpand" 
                         HeaderText="Price" SortExpression="Price"
            DrawBorders="true">
            <ItemStyle BackColor="#396794" ForeColor="white"></ItemStyle>
            <HeaderStyle BackColor="#396794" ForeColor="white"></HeaderStyle>
            <FooterStyle BackColor="#396794" ForeColor="white"></FooterStyle>
        </cc1:ExColumn>
        <cc1:ExColumn DataField="Notes"  ExGroupName="TitleExpand" 
                         HeaderText="Notes" SortExpression="Notes" 
             DrawBorders="true">
            <ItemStyle BackColor="#396794" ForeColor="white"></ItemStyle>
            <HeaderStyle BackColor="#396794" ForeColor="white"></HeaderStyle>
            <FooterStyle BackColor="#396794" ForeColor="white"></FooterStyle>
        </cc1: ExColumn>
        <asp:BoundColumn DataField="Type" 
               HeaderText="Type" SortExpression="Type" />
        <cc1:ExColumnExpand DataField="Publisher" 
                   ExGroupName="PublishExpand" HeaderText="Publisher" 
             SortExpression="Publisher" />
        <cc1:ExColumn DataField="Publication"  ExGroupName="PublishExpand" 
                   HeaderText="Publication Date" 
            SortExpression="Publication" DrawBorders="false">
            <ItemStyle BackColor="#396794" ForeColor="white"></ItemStyle>
        </cc1:ExColumn>
        <asp:BoundColumn DataField="Authors" HeaderText="Authors" 
                   SortExpression="Authors"></asp:BoundColumn>
    </Columns>
</cc1: ExDataGrid>

Conclusion

This server control was quickly written and has much room for improvement. It does implement the IPostback interface so the state of the control is saved during a sort or any other rebinding of data. Additionally, the control's expand and contract functions run via JavaScript so a postback is not necessary. Please make any suggestions and or improvements as necessary. Let me know how it goes!

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