How to: Display Selected Dates from a Database in the Calendar Control
The Calendar control does not directly support data binding — that is, you do not bind the calendar as a whole to a data source. Instead, you write code to get the data you need, and then in the DayRender event, you can compare the currently rendered date against the data you have read from a data source.
To display database data in the Calendar control
Use ADO.NET types to connect to a database and query for the dates to display.
In the Calendar control's DayRender event, compare the date currently being rendered against the data you have retrieved from the database. If there is a match, customize the day display.
Example
The following example reads holiday information from a database into an ADO.NET dataset. The selection gets dates for the current month, defined as the range based on the Calendar control's VisibleDate property, which returns the first date of the current month. Each time the user navigates to a new month, the code reads the holidays for that month. In the DayRender event, code compares the date currently being rendered against the dates returned from the database. If a date matches, the day is marked with a special color.
Note
You will need to add the OnDayRender property to the Calendar control markup to utilize the DayRender event. For example, your code should look like the following:
<asp:Calendar id="Calendar1" OnDayRender=" Calendar1_DayRender" runat="server" ></asp:Calendar>
Protected dsHolidays As DataSet
Protected Sub Page_Load(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
Calendar1.VisibleDate = DateTime.Today
FillHolidayDataset()
End If
End Sub
Protected Sub FillHolidayDataset()
Dim firstDate As New DateTime(Calendar1.VisibleDate.Year, _
Calendar1.VisibleDate.Month, 1)
Dim lastDate As DateTime = GetFirstDayOfNextMonth()
dsHolidays = GetCurrentMonthData(firstDate, lastDate)
End Sub
Protected Function GetFirstDayOfNextMonth() As DateTime
Dim monthNumber, yearNumber As Integer
If Calendar1.VisibleDate.Month = 12 Then
monthNumber = 1
yearNumber = Calendar1.VisibleDate.Year + 1
Else
monthNumber = Calendar1.VisibleDate.Month + 1
yearNumber = Calendar1.VisibleDate.Year
End If
Dim lastDate As New DateTime(yearNumber, monthNumber, 1)
Return lastDate
End Function
Protected Sub Calendar1_VisibleMonthChanged(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.MonthChangedEventArgs) _
Handles Calendar1.VisibleMonthChanged
FillHolidayDataset()
End Sub
Function GetCurrentMonthData(ByVal firstDate As DateTime, _ ByVal lastDate As DateTime) As DataSet
Dim dsMonth As New DataSet
Dim cs As ConnectionStringSettings
cs = ConfigurationManager.ConnectionStrings("ConnectionString1")
Dim connString As String = cs.ConnectionString
Dim dbConnection As New SqlConnection(connString)
Dim query As String
query = "SELECT HolidayDate FROM Holidays " & _
" WHERE HolidayDate >= @firstDate AND HolidayDate < @lastDate"
Dim dbCommand As New SqlCommand(query, dbConnection)
dbCommand.Parameters.Add(New SqlParameter("@firstDate", firstDate))
dbCommand.Parameters.Add(New SqlParameter("@lastDate", lastDate))
Dim sqlDataAdapter As New SqlDataAdapter(dbCommand)
Try
sqlDataAdapter.Fill(dsMonth)
Catch
End Try
Return dsMonth
End Function
Protected Sub Calendar1_DayRender(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.DayRenderEventArgs) _
Handles Calendar1.DayRender
Dim nextDate As DateTime
If Not dsHolidays Is Nothing Then
For Each dr As DataRow In dsHolidays.Tables(0).Rows
nextDate = CType(dr("HolidayDate"), DateTime)
If nextDate = e.Day.Date Then
e.Cell.BackColor = System.Drawing.Color.Pink
End If
Next
End If
End Sub
protected DataSet dsHolidays;
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
Calendar1.VisibleDate = DateTime.Today;
FillHolidayDataset();
}
}
protected void FillHolidayDataset()
{
DateTime firstDate = new DateTime(Calendar1.VisibleDate.Year,
Calendar1.VisibleDate.Month, 1);
DateTime lastDate = GetFirstDayOfNextMonth();
dsHolidays = GetCurrentMonthData(firstDate, lastDate);
}
protected DateTime GetFirstDayOfNextMonth()
{
int monthNumber, yearNumber;
if(Calendar1.VisibleDate.Month == 12)
{
monthNumber = 1;
yearNumber = Calendar1.VisibleDate.Year + 1;
}
else
{
monthNumber = Calendar1.VisibleDate.Month + 1;
yearNumber = Calendar1.VisibleDate.Year;
}
DateTime lastDate = new DateTime(yearNumber, monthNumber, 1);
return lastDate;
}
protected DataSet GetCurrentMonthData(DateTime firstDate,
DateTime lastDate)
{
DataSet dsMonth = new DataSet();
ConnectionStringSettings cs;
cs = ConfigurationManager.ConnectionStrings["ConnectionString1"];
String connString = cs.ConnectionString;
SqlConnection dbConnection = new SqlConnection(connString);
String query;
query = "SELECT HolidayDate FROM Holidays " + _
" WHERE HolidayDate >= @firstDate AND HolidayDate < @lastDate";
SqlCommand dbCommand = new SqlCommand(query, dbConnection);
dbCommand.Parameters.Add(new SqlParameter("@firstDate",
firstDate));
dbCommand.Parameters.Add(new SqlParameter("@lastDate", lastDate));
SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(dbCommand);
try
{
sqlDataAdapter.Fill(dsMonth);
}
catch {}
return dsMonth;
}
protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)
{
DateTime nextDate;
if(dsHolidays != null)
{
foreach(DataRow dr in dsHolidays.Tables[0].Rows)
{
nextDate = (DateTime) dr["HolidayDate"];
if(nextDate == e.Day.Date)
{
e.Cell.BackColor = System.Drawing.Color.Pink;
}
}
}
}
protected void Calendar1_VisibleMonthChanged(object sender,
MonthChangedEventArgs e)
{
FillHolidayDataset();
}
This example builds a query based on the dates in the currently displayed month. The VisibleDate property returns the first date of the current month. (The VisibleDate property is not set until the user has navigated in the calendar, so the first time the page is displayed, the code sets the VisibleDate property manually.) A helper function in the code calculates the first day of the next month based on the VisibleDate property, and can therefore be used to build a date range within the current month.
Compiling the Code
The code assumes that you are using a SQL Server database containing the table Holidays. The table has the column HolidayDate. The connection string required to connect to the database is stored in the Web.config file under the name ConnectionString1.
The code assumes that you have imported the namespaces System.Data and System.Data.SqlClient so that references to DataSet, SqlConnection, and other objects can be used without being fully qualified.
Robust Programming
When querying the database, you should always enclose the execution of the query (in this example, when calling the data adapter's Fill method) in a try-catch block.