Entity Framework Code First

• Mar 14, 2021
• 5 minutes to read

A SchedulerDataStorage can be bound to a data source created using the Entity Framework Code First approach. The following code demonstrates how to implement appointment and resource objects.

Appointments

View Example

EFAppointment.cs

class EFAppointment
{
    [Key]
    public int UniqueID {get;set;}
    [Required]
    public int Type {get;set;}
    [Required]
    public DateTime StartDate {get;set;}
    [Required]
    public DateTime EndDate {get;set;}
    public bool AllDay {get;set;}
    public string Subject {get;set;}
    public string Location {get;set;}
    public string Description { get; set; }
    public int Status {get;set;}
    public int Label {get;set;}
    public string ResourceIDs {get;set;}
    public string ReminderInfo {get;set;}
    public string RecurrenceInfo {get;set;}
}

EFAppointment.vb

Friend Class EFAppointment
    <Key> _
    Public Property UniqueID() As Integer
    <Required> _
    Public Property Type() As Integer
    <Required> _
    Public Property StartDate() As Date
    <Required> _
    Public Property EndDate() As Date
    Public Property AllDay() As Boolean
    Public Property Subject() As String
    Public Property Location() As String
    Public Property Description() As String
    Public Property Status() As Integer
    Public Property Label() As Integer
    Public Property ResourceIDs() As String
    Public Property ReminderInfo() As String
    Public Property RecurrenceInfo() As String
End Class

Resources

View Example

EFResource.cs

class EFResource
{
    [Key]
    public int UniqueID { get; set; }
    public int ResourceID { get; set; }
    public string ResourceName { get; set; }
    public byte[] Image { get; set; }
    public int Color
    {
        get
        {
            return ColorEx.ToArgb();
        }
        set
        {
            ColorEx = new MyColor(value);
        }
    }
    public MyColor ColorEx { get; set; }

}

class MyColor
{
    public byte A { get; set; }
    public byte R { get; set; }
    public byte G { get; set; }
    public byte B { get; set; }

    public MyColor() { }
    public MyColor(byte a, byte r, byte g, byte b) { A = a; R = r; G = g; B = b; }
    public MyColor(Color color) { A = color.A; R = color.R; G = color.G; B = color.B; }
    public MyColor(int argb)
    {
        byte[] bytes = BitConverter.GetBytes(argb);
        A = bytes[0];
        R = bytes[1];
        G = bytes[2];
        B = bytes[3];
    }

    public Color ToColor() { return Color.FromArgb(A, R, G, B); }
    public static MyColor FromColor(Color color) { return new MyColor(color.A, color.R, color.G, color.B); }
    public int ToArgb()
    {
        byte[] bytes = new byte[] { A, R, G, B };
        return BitConverter.ToInt32(bytes, 0);
    }

}

EFResource.vb

Friend Class EFResource
    <Key> _
    Public Property UniqueID() As Integer
    Public Property ResourceID() As Integer
    Public Property ResourceName() As String
    Public Property Image() As Byte()
    Public Property Color() As Integer
        Get
            Return ColorEx.ToArgb()
        End Get
        Set(ByVal value As Integer)
            ColorEx = New MyColor(value)
        End Set
    End Property
    Public Property ColorEx() As MyColor

End Class

Friend Class MyColor
    Public Property A() As Byte
    Public Property R() As Byte
    Public Property G() As Byte
    Public Property B() As Byte

    Public Sub New()
    End Sub
    Public Sub New(ByVal a As Byte, ByVal r As Byte, ByVal g As Byte, ByVal b As Byte)
        Me.A = a
        Me.R = r
        Me.G = g
        Me.B = b
    End Sub
    Public Sub New(ByVal color As Color)
        A = color.A
        R = color.R
        G = color.G
        B = color.B
    End Sub
    Public Sub New(ByVal argb As Integer)
        Dim bytes() As Byte = BitConverter.GetBytes(argb)
        A = bytes(0)
        R = bytes(1)
        G = bytes(2)
        B = bytes(3)
    End Sub

    Public Function ToColor() As Color
        Return Color.FromArgb(A, R, G, B)
    End Function
    Public Shared Function FromColor(ByVal color As Color) As MyColor
        Return New MyColor(color.A, color.R, color.G, color.B)
    End Function
    Public Function ToArgb() As Integer
        Dim bytes() As Byte = { A, R, G, B }
        Return BitConverter.ToInt32(bytes, 0)
    End Function

End Class

DbContext

The DbContext class descendant is required to retrieve data from the database. It is implemented as follows:

View Example

SchedulerContext.cs

class SchedulerContext:DbContext
{
    public DbSet<EFAppointment> EFAppointments { get; set; }
    public DbSet<EFResource> EFResources { get; set; }
}

SchedulerContext.vb

Friend Class SchedulerContext
    Inherits DbContext

    Public Property EFAppointments() As DbSet(Of EFAppointment)
    Public Property EFResources() As DbSet(Of EFResource)
End Class

Mappings

Before binding to a data source we have to map data fields to appointment and resource properties. The code that creates the required mappings is shown below.

View Example

Form1.cs

this.schedulerStorage1.Appointments.Mappings.AllDay = "AllDay";
this.schedulerStorage1.Appointments.Mappings.AppointmentId = "UniqueID";
this.schedulerStorage1.Appointments.Mappings.Description = "Description";
this.schedulerStorage1.Appointments.Mappings.End = "EndDate";
this.schedulerStorage1.Appointments.Mappings.Label = "Label";
this.schedulerStorage1.Appointments.Mappings.Location = "Location";
this.schedulerStorage1.Appointments.Mappings.RecurrenceInfo = "RecurrenceInfo";
this.schedulerStorage1.Appointments.Mappings.ReminderInfo = "ReminderInfo";
this.schedulerStorage1.Appointments.Mappings.ResourceId = "ResourceIDs";
this.schedulerStorage1.Appointments.Mappings.Start = "StartDate";
this.schedulerStorage1.Appointments.Mappings.Status = "Status";
this.schedulerStorage1.Appointments.Mappings.Subject = "Subject";
this.schedulerStorage1.Appointments.Mappings.Type = "Type";

Form1.vb

Me.schedulerStorage1.Appointments.Mappings.AllDay = "AllDay"
Me.schedulerStorage1.Appointments.Mappings.AppointmentId = "UniqueID"
Me.schedulerStorage1.Appointments.Mappings.Description = "Description"
Me.schedulerStorage1.Appointments.Mappings.End = "EndDate"
Me.schedulerStorage1.Appointments.Mappings.Label = "Label"
Me.schedulerStorage1.Appointments.Mappings.Location = "Location"
Me.schedulerStorage1.Appointments.Mappings.RecurrenceInfo = "RecurrenceInfo"
Me.schedulerStorage1.Appointments.Mappings.ReminderInfo = "ReminderInfo"
Me.schedulerStorage1.Appointments.Mappings.ResourceId = "ResourceIDs"
Me.schedulerStorage1.Appointments.Mappings.Start = "StartDate"
Me.schedulerStorage1.Appointments.Mappings.Status = "Status"
Me.schedulerStorage1.Appointments.Mappings.Subject = "Subject"
Me.schedulerStorage1.Appointments.Mappings.Type = "Type"

View Example

Form1.cs

this.schedulerStorage1.Resources.Mappings.Caption = "ResourceName";
this.schedulerStorage1.Resources.Mappings.Color = "Color";
this.schedulerStorage1.Resources.Mappings.Id = "ResourceID";
this.schedulerStorage1.Resources.Mappings.Image = "Image";

Form1.vb

Me.schedulerStorage1.Resources.Mappings.Caption = "ResourceName"
Me.schedulerStorage1.Resources.Mappings.Color = "Color"
Me.schedulerStorage1.Resources.Mappings.Id = "ResourceID"
Me.schedulerStorage1.Resources.Mappings.Image = "Image"

Database Initialization

Handle the Form.Load event to create the database, fill it with initial data and specify appointment and resource binding sources.

View Example

Form1.cs

Database.SetInitializer(new SchedulerContextSeedInilializer());
context = new SchedulerContext();

context.Database.Initialize(false);
context.EFAppointments.Load();
context.EFResources.Load();

eFAppointmentBindingSource.DataSource = context.EFAppointments.Local.ToBindingList<EFAppointment>();
eFResourceBindingSource.DataSource = context.EFResources.Local.ToBindingList<EFResource>();

Form1.vb

Database.SetInitializer(New SchedulerContextSeedInilializer())
context = New SchedulerContext()

context.Database.Initialize(False)
context.EFAppointments.Load()
context.EFResources.Load()

eFAppointmentBindingSource.DataSource = context.EFAppointments.Local.ToBindingList()
eFResourceBindingSource.DataSource = context.EFResources.Local.ToBindingList()

Not the use of the System.Data.Entity.DbExtensions.ToBindingList<T> method as the source for data binding.

Database Commit

The SaveChanges method of DbContext descendant - the SchedulerContext object - is used to commit changes to the data source. Subscribe to the SchedulerDataStorage.AppointmentsInserted, SchedulerDataStorage.AppointmentsChanged and the SchedulerDataStorage.AppointmentsDeleted events to save the SchedulerContext object.

To exclude the identity field from the fields being committed to the data source, set the AppointmentStorage.CommitIdToDataSource property to false.