Creating a Dropdown in an ASP.NET GridView Control

To create a Dropdown control in an ASP.NET GridView control, you create a template field and wire the behavior to populate the dropdown in the RowDataBound event of the GridView.  Here is a simple example.

In the GridView, we created the template field with an ItemTemplate and inserted the Dropdown control.  Also, note that we wired up the OnRowDataBound event in the GridView’s tag.

<asp:gridview id="gvSeminarSchedule" onrowdatabound="gvSeminarSchedule_RowDataBound"
	runat="server" autogeneratecolumns="False" onselectedindexchanged="gvSeminarSchedule_SelectedIndexChanged"
	onselectedindexchanging="gvSeminarSchedule_SelectedIndexChanging" datakeynames="SeminarScheduleID">
	<alternatingrowstyle cssclass="GridRowAlternate" />
	<rowstyle cssclass="GridRowStandard" />
	<headerstyle cssclass="ItemLabelCenter" />
	<selectedrowstyle cssclass="GridRowSelected" />
	<columns>
		<asp:boundfield datafield="SeminarScheduleID" headertext="ID" />
		<asp:boundfield datafield="FormattedStartDate" headertext="Seminar Start" htmlencode="false" />
		<asp:boundfield datafield="FormattedEndDate" headertext="Seminar End" htmlencode="false" />
		<asp:boundfield datafield="RegisterStartDateString" headertext="Register Start" />
		<asp:boundfield datafield="RegisterEndDateString" headertext="Register End" />
		<asp:boundfield datafield="RegisterEarlyPriceEndDateString" headertext="Register Early Price End" insertvisible="False" readonly="True" />
		<asp:templatefield headertext="Students">
			<itemtemplate>
				<asp:dropdownlist runat="server" id="ddStudent"></asp:dropdownlist>
			</itemtemplate>
		</asp:templatefield>
	</columns>
</asp:gridview>

In the page behind, we are testing for a DataRow, and if it is then we find the DropDown control instance for the row and populate it.

protected void gvSeminarSchedule_RowDataBound( object sender, GridViewRowEventArgs e )
{
	if ( e.Row.RowType == DataControlRowType.DataRow )
	{
		SeminarSchedule seminarSchedule = new SeminarSchedule();
		seminarSchedule.SeminarScheduleID = e.Row.Cells[ 0 ].Text.ToInt();
		DropDownList ddl = (DropDownList)e.Row.FindControl( "ddStudent" );
		ddl.DataSource = seminarSchedule.ListStudentsByNameLastFirst();
		ddl.DataMember = "PersonID";
		ddl.DataTextField = "FullNameLastFirst";
		ddl.DataBind();
	}
}

CSS Colors and Hex Values

The following list are colors and their hex values that all browsers will understand.

AliceBlue #F0F8FF
AntiqueWhite #FAEBD7
Aqua #00FFFF
Aquamarine #7FFFD4
Azure #F0FFFF
Beige #F5F5DC
Bisque #FFE4C4
Black #000000
BlanchedAlmond #FFEBCD
Blue #0000FF
BlueViolet #8A2BE2
Brown #A52A2A
BurlyWood #DEB887
CadetBlue #5F9EA0
Chartreuse #7FFF00
Chocolate #D2691E
Coral #FF7F50
CornflowerBlue #6495ED
Cornsilk #FFF8DC
Crimson #DC143C
Cyan #00FFFF
DarkBlue #00008B
DarkCyan #008B8B
DarkGoldenRod #B8860B
DarkGray #A9A9A9
DarkGreen #006400
DarkKhaki #BDB76B
DarkMagenta #8B008B
DarkOliveGreen #556B2F
Darkorange #FF8C00
DarkOrchid #9932CC
DarkRed #8B0000
DarkSalmon #E9967A
DarkSeaGreen #8FBC8F
DarkSlateBlue #483D8B
DarkSlateGray #2F4F4F
DarkTurquoise #00CED1
DarkViolet #9400D3
DeepPink #FF1493
DeepSkyBlue #00BFFF
DimGray #696969
DodgerBlue #1E90FF
FireBrick #B22222
FloralWhite #FFFAF0
ForestGreen #228B22
Fuchsia #FF00FF
Gainsboro #DCDCDC
GhostWhite #F8F8FF
Gold #FFD700
GoldenRod #DAA520
Gray #808080
Green #008000
GreenYellow #ADFF2F
HoneyDew #F0FFF0
HotPink #FF69B4
IndianRed #CD5C5C
Indigo #4B0082
Ivory #FFFFF0
Khaki #F0E68C
Lavender #E6E6FA
LavenderBlush #FFF0F5
LawnGreen #7CFC00
LemonChiffon #FFFACD
LightBlue #ADD8E6
LightCoral #F08080
LightCyan #E0FFFF
LightGoldenRodYellow #FAFAD2
LightGrey #D3D3D3
LightGreen #90EE90
LightPink #FFB6C1
LightSalmon #FFA07A
LightSeaGreen #20B2AA
LightSkyBlue #87CEFA
LightSlateGray #778899
LightSteelBlue #B0C4DE
LightYellow #FFFFE0
Lime #00FF00
LimeGreen #32CD32
Linen #FAF0E6
Magenta #FF00FF
Maroon #800000
MediumAquaMarine #66CDAA
MediumBlue #0000CD
MediumOrchid #BA55D3
MediumPurple #9370D8
MediumSeaGreen #3CB371
MediumSlateBlue #7B68EE
MediumSpringGreen #00FA9A
MediumTurquoise #48D1CC
MediumVioletRed #C71585
MidnightBlue #191970
MintCream #F5FFFA
MistyRose #FFE4E1
Moccasin #FFE4B5
NavajoWhite #FFDEAD
Navy #000080
OldLace #FDF5E6
Olive #808000
OliveDrab #6B8E23
Orange #FFA500
OrangeRed #FF4500
Orchid #DA70D6
PaleGoldenRod #EEE8AA
PaleGreen #98FB98
PaleTurquoise #AFEEEE
PaleVioletRed #D87093
PapayaWhip #FFEFD5
PeachPuff #FFDAB9
Peru #CD853F
Pink #FFC0CB
Plum #DDA0DD
PowderBlue #B0E0E6
Purple #800080
Red #FF0000
RosyBrown #BC8F8F
RoyalBlue #4169E1
SaddleBrown #8B4513
Salmon #FA8072
SandyBrown #F4A460
SeaGreen #2E8B57
SeaShell #FFF5EE
Sienna #A0522D
Silver #C0C0C0
SkyBlue #87CEEB
SlateBlue #6A5ACD
SlateGray #708090
Snow #FFFAFA
SpringGreen #00FF7F
SteelBlue #4682B4
Tan #D2B48C
Teal #008080
Thistle #D8BFD8
Tomato #FF6347
Turquoise #40E0D0
Violet #EE82EE
Wheat #F5DEB3
White #FFFFFF
WhiteSmoke #F5F5F5
Yellow #FFFF00
YellowGreen #9ACD32

Supporting Multiple Dates in .NET Calendar Control

This post will help you to support using multiple dates in a calendar control.  You will be able to populate your control with multiple dates from a data source, and then allow your users to interact with those selections, selecting or deselecting additional or existing dates for saving back to your data source.

The calendar control does not support databinding, so you have to use the DayRender event to make your selections appear.   You’ll also need to use the SelectionChanged event to manage selections and then some kind of a persistent storage that can live on the page like a session or use the viewstate bag.

So, anything coming in from the database gets handled in the DayRender event, and any changes get handled in the SelectionChanged event.  All of this should point to persistant storage such as a session variable or in the view state.  When you want to save what the user did, grab whatever you have in your session or view state and send it back to the database.

Here is my html for the control.

<asp:calendar id="cSeminarDate" runat="server" enableviewstate="true"
	daynameformat="Shortest" cssclass="CalendarStandard"
	onselectionchanged="cSeminarDate_SelectionChanged"
	ondayrender="cSeminarDate_DayRender">
	<dayheaderstyle cssclass="CalendarStandardDayHeaderStyle" />
	<daystyle cssclass="CalendarStandardDayStyle" />
	<nextprevstyle cssclass="CalendarStandardNextPrevStyle" />
	<othermonthdaystyle cssclass="CalendarStandardOtherMonthDayStyle" />
	<selecteddaystyle cssclass="CalendarStandardSelectedDayStyle" />
	<selectorstyle cssclass="CalendarStandardSelectorStyle" />
	<titlestyle cssclass="CalendarStandardTitleStyle" />
	<todaydaystyle cssclass="CalendarStandardTodayDayStyle" />
	<weekenddaystyle cssclass="CalendarStandardWeekendDayStyle" />
</asp:calendar>

What I did in this example was to create a session variable to store a List<DateTime>.   After populating my list with selected dates elsewhere in code, in the DayRender event (this event fires for every date in the calendar control), I compared the date that the control was currently drawing with my list, and if there was a match, I set the cell’s css class property to my selector style.

The following code is what I am using to populate my calendar control with selected dates.

protected void cSeminarDate_DayRender( object sender, DayRenderEventArgs e )
{
	List<DateTime> dt = SessionManager.GetInstance( HttpContext.Current ).SeminarDateList;
	foreach ( DateTime d in dt )
	{
		if ( d.ToShortDateString() == e.Day.Date.ToShortDateString() )
		{
			e.Cell.CssClass = "CalendarStandardSelectorStyle";
		}
	}
}

After I have my calendar populated with selected dates, my users are now in a position to deselect existing dates as well as to add new dates.  The following code below uses the SelectionChanged event in conjunction with the session.

protected void cSeminarDate_SelectionChanged( object sender, EventArgs e )
{
	if ( SessionManager.GetInstance( HttpContext.Current ).SeminarDateList.Contains(cSeminarDate.SelectedDate) )
	{
		SessionManager.GetInstance( HttpContext.Current ).SeminarDateList.Remove( cSeminarDate.SelectedDate );
		cSeminarDate.SelectedDates.Remove( cSeminarDate.SelectedDate );
	}
	else
	{
		SessionManager.GetInstance( HttpContext.Current ).SeminarDateList.Add( cSeminarDate.SelectedDate );
	}

	foreach ( DateTime dt in SessionManager.GetInstance( HttpContext.Current ).SeminarDateList )
	{
		cSeminarDate.SelectedDates.Add( dt );
	}
}

Where you see references to SessionManager.GetInstance( HttpContext.Current ).SeminarDateList, you can replace with Session[“SeminarDateList” ] as I manage my sessions explicitly in a single location.  Make sure to remember to clear your session when you init your page.  I have an InitUI() method I call if not a postback in the Page_Load event and elsewhere.  In there I do this 

SessionManager.GetInstance( HttpContext.Current ).SeminarDateList.Clear();

Hope this helps.