Need help about datagrid

i have datagrid(see bellow) there is columns with date time how i can make background red where rooomNumer is 777 from 1/8/2011 to 5/8/2011 with code behind? Room number column bind with observable collection

 ObservableCollection<RoomsInfoData> _RoomsInfoCollection = new ObservableCollection<RoomsInfoData>();
        public RoomsInfo()
   public ObservableCollection<RoomsInfoData> RoomsInfoCollection
        {
            get { return _RoomsInfoCollection; }
        }

        public class RoomsInfoData
        {
            public string RoomType { get; set; }
            public string RoomNumber { get; set; }
            public string RoomStatus { get; set; }
        }
HProDataContext db = new HProDataContext();
            var _RoomNumber = (from d in db.SelectRooms select d.roomnumber).ToList();
            var _RoomType = (from d in db.SelectRooms select d.roo开发者_开发知识库mtype).ToList();
            var _RoomStatus = (from d in db.SelectRooms select d.status).ToList();

            for (int i = 0; i < _RoomNumber.Count; i++)
            {

                _RoomsInfoCollection.Add(new RoomsInfoData { RoomNumber = _RoomNumber[i], RoomType = _RoomType[i], RoomStatus = _RoomStatus[i] });
            }

Assuming that

1. "this" refers to your window or user control in which this data grid is placed.
2. this.dataGrid refers to your datagrid in which you have added columns from code behind.

We will specify a style in the Window / UserControl's Resources collection ... like this

    <UserControl.Resources> <!-- could be Window.Resources if datagrid lies in a Window -->
            <Style x:Key="RoomNumberValidationCellStyle"
                       TargetType="{x:Type DataGridCell}"> <!-- DataGridCell because we need to apply this style to specific columns -->
                    <Style.Triggers>
                            <DataTrigger Binding="{Binding Path=RoomNumber}" Value="777">
                                    <Setter Property="Background" Value="Red" />
                            </DataTrigger>
                    </Style.Triggers>
            </Style>
    </UserControl.Resources>

in code behind after you set all columns to this.dataGrid ... do this...

    foreach(var col in this.dataGrid.Columns)
    {
            var headerText = (string)col.Header;
            if (headerText == "1/8/2011" || headerText.Header == "2/8/2011"
            || headerText.Header == "3/8/2011" || headerText.Header == "4/8/2011"
            || headerText.Header == "5/8/2011")
                    col.CellStyle = this.FindResource("RoomNumberValidationCellStyle") as Style;
    }

Let me know if this helps.

<Style x:Key="RedRowStyle" TargetType="{x:Type dg:DataGridRow}">
        <Setter Property="Background" Value="Red"/>
        <Style.Triggers>
            <DataTrigger Binding="{Binding PropertyName}" Value="777" >
                <Setter Property="Background" Value="DarkGray" />
                <Setter Property="Foreground" Value="White" />
            </DataTrigger>
        </Style.Triggers>
    </Style>

Just replace PropertyName with the property in the ViewModel where the value will be 777 and apply to the proper rows.