Business Logic Framework - Tutorial 31:
Business Logic Framework makes it very simple to deal with blob/binary data
types. A blob field in the database gets mapped to BinaryField in the Business
Logic Framework. When an object with a BinaryField is loaded, the BinaryField's
value is automatically filled with the binary array from the underlying record
in the database. To save the BinaryField value, simply set the binary
array and update the business object just like you would in normal update
scenario.
 Even
though samples are available both for Web and Windows, the code
in this tutorial refers to the windows version. The main
difference between the two is that the ASP.NET sample uses a
HTTP Handler to serve the image. |
| 1 |
Private
Sub Button_LoadCustomer_Click(
ByVal
sender
As Object, ByVal e
As EventArgs) |
| 2 |
If Not [String].IsNullOrEmpty(
Me.TextBox_CustomerID.Text)
Then |
| 3 |
If Me .Customer
Is Nothing Then |
| 4 |
Me.Customer =
New Customers() |
| 5 |
End If |
| 6 |
' We can use the Parse method of the CustomerID field to parse the value from the TextBox
|
| 7 |
Me.Customer.CustomerID.Parse(
Me.TextBox_CustomerID.Text) |
| 8 |
' Calling the Load method will Load all the fields of the Customer object.
|
| 9 |
' By default all fields will be loaded but if you can control what fields are loaded by setting their Visible property value.
|
| 10 |
If Me .Customer.Load()
Then |
| 11 |
Me.Button_Save.Enabled =
True |
| 12 |
' Lets assign the Customer's FirstName and LastName values to the text boxes.
|
| 13 |
Me.TextBox_FirstName.Text =
Me.Customer.FirstName.Value |
| 14 |
Me.TextBox_LastName.Text =
Me.Customer.LastName.Value |
| 15 |
' Every type of field object has a property called IsNull so it makes it relatively very simple
|
| 16 |
' to check if the field value is null or not. This provides a consistent way of dealing with Null values in the database.
|
| 17 |
If Not Me.Customer.Photo.IsNull
Then |
| 18 |
' Since the Photo is of type BinaryField and it contains a Byte array.
|
| 19 |
' The Byte array can be translated into an Image Bitmap object as shown below.
|
| 20 |
Me.PictureBox_Photo.Image =
New Bitmap(
New MemoryStream(
Me.Customer.Photo.Value)) |
| 21 |
Else |
| 22 |
' Since there is no image in the database we set the picture box's Image property to null.
|
| 23 |
Me.PictureBox_Photo.Image =
Nothing
|
| 24 |
End If |
| 25 |
End If |
| 26 |
End If |
| 27 |
End
Sub |
| 28 |
|
| 1 |
private
void Button_LoadCustomer_Click(
object
sender, EventArgs e) |
| 2 |
{ |
| 3 |
if (!String.IsNullOrEmpty(
this.TextBox_CustomerID.Text)) |
| 4 |
{ |
| 5 |
if (this.Customer ==
null) |
| 6 |
{ |
| 7 |
this.Customer =
new Customers(); |
| 8 |
} |
| 9 |
// We can use the Parse method of the CustomerID field to parse the value from the TextBox
|
| 10 |
this.Customer.CustomerID.Parse(
this.TextBox_CustomerID.Text); |
| 11 |
// Calling the Load method will Load all the fields of the Customer object.
|
| 12 |
// By default all fields will be loaded but if you can control what fields are loaded by setting their Visible property value.
|
| 13 |
if (this.Customer.Load()) |
| 14 |
{ |
| 15 |
this.Button_Save.Enabled =
true; |
| 16 |
// Lets assign the Customer's FirstName and LastName values to the text boxes.
|
| 17 |
this.TextBox_FirstName.Text =
this.Customer.FirstName.Value; |
| 18 |
this.TextBox_LastName.Text =
this.Customer.LastName.Value; |
| 19 |
// Every type of field object has a property called IsNull so it makes it relatively very simple
|
| 20 |
// to check if the field value is null or not. This provides a consistent way of dealing with Null values in the database.
|
| 21 |
if (!this.Customer.Photo.IsNull) |
| 22 |
{ |
| 23 |
// Since the Photo is of type BinaryField and it contains a Byte array.
|
| 24 |
// The Byte array can be translated into an Image Bitmap object as shown below.
|
| 25 |
this.PictureBox_Photo.Image =
new Bitmap(
new MemoryStream(
this.Customer.Photo.Value)); |
| 26 |
} |
| 27 |
else |
| 28 |
{ |
| 29 |
// Since there is no image in the database we set the picture box's Image property to null.
|
| 30 |
this.PictureBox_Photo.Image =
null; |
| 31 |
} |
| 32 |
} |
| 33 |
} |
| 34 |
} |
| 35 |
|
| 1 |
private
void Button_Save_Click(
object
sender, EventArgs e) |
| 2 |
{ |
| 3 |
if (this.Customer !=
null &&
this.Customer.IsLoaded) |
| 4 |
{ |
| 5 |
// Assign the ObjectMode to Save and this will ensure that any field values that are assigned
|
| 6 |
// from this point onwards, their UseInSave will be set to True.
|
| 7 |
this.Customer.ObjectMode = Akal.QuickObjects.ObjectBase.ObjectModes.Save; |
| 8 |
this.Customer.FirstName.Value =
this.TextBox_FirstName.Text; |
| 9 |
this.Customer.LastName.Value =
this.TextBox_LastName.Text; |
| 10 |
// Lets check to see if the User actually supplied an image or not.
|
| 11 |
// Or may be the user wants to remove the photo.
|
| 12 |
if (this.CheckBox_Remove.Checked ||
this.PictureBox_Photo.Image ==
null) |
| 13 |
{ |
| 14 |
// Since the user did not supply an image, we can set the Photo to null.
|
| 15 |
this.Customer.Photo.IsNull =
true; |
| 16 |
} |
| 17 |
else |
| 18 |
{ |
| 19 |
// We can convert the Image to a Byte array as shown below.
|
| 20 |
MemoryStream stream =
new MemoryStream(); |
| 21 |
this.PictureBox_Photo.Image.Save(stream,
this.PictureBox_Photo.Image.RawFormat); |
| 22 |
// We can simply assign an array of bytes to the BinaryField's Value property.
|
| 23 |
this.Customer.Photo.Value = stream.ToArray(); |
| 24 |
} |
| 25 |
// Calling the Update method will update the underlying Customer record.
|
| 26 |
// The binary fields, large text, or Xml Fields are automatically handled as well.
|
| 27 |
if (this.Customer.Update()) |
| 28 |
{ |
| 29 |
MessageBox.Show(
"Saved!"
); |
| 30 |
} |
| 31 |
else |
| 32 |
{ |
| 33 |
MessageBox.Show(
this.Customer.ErrorString); |
| 34 |
} |
| 35 |
} |
| 36 |
else |
| 37 |
{ |
| 38 |
this.Button_Save.Enabled =
false
; |
| 39 |
} |
| 40 |
} |
| 41 |
|
| 1 |
Private
Sub Button_Save_Click(
ByVal
sender As Object, ByVal e
As EventArgs) |
| 2 |
If Me.Customer IsNot
Nothing
AndAlso Me.Customer.IsLoaded
Then |
| 3 |
' Assign the ObjectMode to Save and this will ensure that any field values that are assigned
|
| 4 |
' from this point onwards, their UseInSave will be set to True.
|
| 5 |
Me.Customer.ObjectMode = Akal.QuickObjects.ObjectBase.ObjectModes.Save |
| 6 |
Me.Customer.FirstName.Value =
Me.TextBox_FirstName.Text |
| 7 |
Me.Customer.LastName.Value =
Me.TextBox_LastName.Text |
| 8 |
' Lets check to see if the User actually supplied an image or not.
|
| 9 |
' Or may be the user wants to remove the photo.
|
| 10 |
If Me .CheckBox_Remove.Checked
OrElse Me.PictureBox_Photo.Image
Is Nothing Then |
| 11 |
' Since the user did not supply an image, we can set the Photo to null.
|
| 12 |
Me.Customer.Photo.IsNull =
True |
| 13 |
Else |
| 14 |
' We can convert the Image to a Byte array as shown below.
|
| 15 |
Dim stream
As New MemoryStream() |
| 16 |
Me.PictureBox_Photo.Image.Save(stream,
Me.PictureBox_Photo.Image.RawFormat) |
| 17 |
' We can simply assign an array of bytes to the BinaryField's Value property.
|
| 18 |
Me.Customer.Photo.Value = stream.ToArray() |
| 19 |
End If |
| 20 |
' Calling the Update method will update the underlying Customer record.
|
| 21 |
' The binary fields, large text, or Xml Fields are automatically handled as well.
|
| 22 |
If Me .Customer.Update()
Then |
| 23 |
MessageBox.Show(
"Saved!"
) |
| 24 |
Else |
| 25 |
MessageBox.Show(
Me.Customer.ErrorString) |
| 26 |
End If |
| 27 |
Else |
| 28 |
Me.Button_Save.Enabled =
False
|
| 29 |
End If |
| 30 |
End Sub |
| 31 |
|
