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Serialization

   

Object Serialization and De-Serialization

 

Introduction

Consider the following form:

Serialization

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace Cars1
{
    public partial class Exercise : Form
    {
        public Exercise()
        {
            InitializeComponent();
        }

        private void btnWrite_Click(object sender, EventArgs e)
        {
            var Make  = txtMake.Text;
            var Model = txtModel.Text;
            var Year  = uint.Parse(txtYear.Text);
            var Color = txtColor.Text;

            var stmCar = new FileStream("Car1.car", FileMode.Create);
            var bnwCar = new BinaryWriter(stmCar);

            try
            {
                bnwCar.Write(Make);
                bnwCar.Write(Model);
                bnwCar.Write(Year);
                bnwCar.Write(Color);
            }
            finally
            {
                bnwCar.Close();
                stmCar.Close();
            }
        }
    }
}

Here is an example of running the program:

Serialization

This is an example of the techniques used in file processing to save individual data of primitive types:

Saving the variables in a method

The values can be retrieved with the following code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace Cars1
{
    public partial class Exercise : Form
    {
        public Exercise()
        {
            InitializeComponent();
        }

        private void btnWrite_Click(object sender, EventArgs e)
        {
            var Make  = txtMake.Text;
            var Model = txtModel.Text;
            var Year  = uint.Parse(txtYear.Text);
            var Color = txtColor.Text;

            var stmCar = new FileStream("Car1.car", FileMode.Create);
            var bnwCar = new BinaryWriter(stmCar);

            try
            {
                bnwCar.Write(Make);
                bnwCar.Write(Model);
                bnwCar.Write(Year);
                bnwCar.Write(Color);
            }
            finally
            {
                bnwCar.Close();
                stmCar.Close();
            }
        }

        private void btnRead_Click(object sender, EventArgs e)
        {
            var stmCar = new FileStream("Car1.car", FileMode.Open);
            var bnrCar = new BinaryReader(stmCar);

            try
            {
                txtMake.Text = bnrCar.ReadString();
                txtModel.Text = bnrCar.ReadString();
                txtYear.Text = bnrCar.ReadUInt32().ToString();
                txtColor.Text = bnrCar.ReadString();
            }
            finally
            {
                bnrCar.Close();
                stmCar.Close();
            }
        }
    }
}

In the same way, you can save the individual fields of a class or you can retrieve the individual fields of a car:

Saving the individual parts of an object

Here is an example:

Class: Car.cs
using System;

namespace Cars1
{
    public class Car
    {
        public string Make;
        public string Model;
        public uint Year;
        public int Color;
    }
}
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace Cars1
{
    public partial class Exercise : Form
    {
        public Exercise()
        {
            InitializeComponent();
        }

        private void btnWrite_Click(object sender, EventArgs e)
        {
            var vehicle = new Car();
            vehicle.Make  = txtMake.Text;
            vehicle.Model = txtModel.Text;
            vehicle.Year  = uint.Parse(txtYear.Text);
            vehicle.Color = txtColor.Text;

            var stmCar = new FileStream("Car2.car", FileMode.Create);
            var bnwCar = new BinaryWriter(stmCar);

            try
            {
                bnwCar.Write(vehicle.Make);
                bnwCar.Write(vehicle.Model);
                bnwCar.Write(vehicle.Year);
                bnwCar.Write(vehicle.Color);
            }
            finally
            {
                bnwCar.Close();
                stmCar.Close();
            }
        }

        private void btnRead_Click(object sender, EventArgs e)
        {
            var stmCar = new FileStream("Car2.car", FileMode.Open);
            var bnrCar = new BinaryReader(stmCar);

            try
            {
                var vehicle = new Car();
                vehicle.Make = bnrCar.ReadString();
                vehicle.Model = bnrCar.ReadString();
                vehicle.Year = bnrCar.ReadUInt32();
                vehicle.Color = bnrCar.ReadString();

                txtMake.Text = vehicle.Make;
                txtModel.Text = vehicle.Model;
                txtYear.Text = vehicle.Year.ToString();
                txtColor.Text = vehicle.Color;
            }
            finally
            {
                bnrCar.Close();
                stmCar.Close();
            }
        }
    }
}

When it comes to a class, the problem with saving individual fields is that you could forget to save one of the fields. For example, considering a Car class, if you don't save the Make information of a Car object and retrieve or open the saved object on another computer, the receiving user would miss some information and the car cannot be completely identifiable. An alternative is to save the whole Car object.

Object serialization consists of saving a whole object as one instead of its individual fields:

Serialization

In other words, a variable declared from a class can be saved to a stream and then the saved object can be retrieved later or on another computer. The .NET Framework supports two types of object serialization: binary and SOAP.

Practical Learning: Introducing Serialization

  1. Start Microsoft Visual Studio
  2. Create a Windows Forms Application named SchoolCatalog1
  3. To create a new form, on the main menu, click Projects -> Add Windows Form...
  4. Set the Name to CourseEditor and click Add
  5. Design the form as follows:
     
    School
    Control (Name) DialogResult Text Modifiers
    Label Label     Course Code:  
    TextBox Text Box txtCourseCode     Public
    Label Label     Credits:  
    TextBox Text Box txtCredits   1 Public
    Label Label     Course Name:  
    TextBox Text Box txtCourseName     Public
    Button Button btnOK OK OK  
    Button Button btnCancel Cancel Cancel  
    Form
    FormBorderStyle: FixedDialog
    Text: University Catalog - Course Editor
    StartPosition: CenterScreen
    AcceptButton: btnOK
    CancelButton: btnCancel
    MaximizeBox: False
    MinimizeBox: False
    ShowInTaskBar: False
  6. In the Solution Explorer, right-click Form1.cs and click Rename
  7. Type SchoolCatalog.cs and press Enter twice (to display that form)
  8. Design the form as follows:
     
    School
    Control (Name) Anchor Text
    DataGridView Data Grid View dgvCourseCataglog Top, Bottom, Left, Right  
    Columns  
    Header Text Name Width
    Course Code CourseCode  
    Course Name CourseName 200
    Credits Credits 60
    Button btnNewCourse Bottom, Left &New Course
    Button btnClose Bottom, Right &Close
    Form
    Text: University Catalog - Course Catalog
    StartPosition: CenterScreen

Serialization

Binary serialization works by processing an object rather than streaming its individual member variables. This means that, to use it, you define an object and initialize it, or "fill" it, with the necessary values and any information you judge necessary. This creates a "state" of the object. It is this state that you prepare to serialize. When you save the object, it is converted into a stream.

To perform binary serialization, there are a few steps you must follow. When creating the class whose objects would be serialized, start it with the [Serializable] attribute. Here is an example:

using System;

namespace Cars1
{
    [Serializable]
    public class Car
    {
        public string Make;
        public string Model;
        public uint Year;
        public int Color;
    }
}

Before serializing an object, you should reference the System.Runtime.Serialization.Formatters.Binary namespace. The class responsible for binary serialization is called BinaryFormatter. This class is equipped with two constructors. The default constructor is used to simply create an object.

After declaring the variable, to actually serialize an object, call the Serialize() method of the BinaryFormatter class. The method is overloaded with two versions. One of the versions of this method uses the following syntax:

public void Serialize(Stream serializationStream, object graph);

The first argument to this method must be an object of a Stream-based class, such as a FileStream object. The second argument must be the object to serialize. This means that, before calling this method, you should have built the object.

Here is an example:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace Cars1
{
    public partial class Exercise : Form
    {
        public Exercise()
        {
            InitializeComponent();
        }

        private void btnWrite_Click(object sender, EventArgs e)
        {
            Car vehicle = new Car();
            vehicle.Make  = txtMake.Text;
            vehicle.Model = txtModel.Text;
            vehicle.Year  = uint.Parse(txtYear.Text);
            vehicle.Color = txtColor.Text;

            FileStream stmCar = new FileStream("Car3.car",
                                               FileMode.Create);
            BinaryFormatter bfmCar = new BinaryFormatter();

            bfmCar.Serialize(stmCar, vehicle);
        }
    }
}

Practical Learning: Serializing an Object

  1. To create a new class, on the main menu, click PROJECT -> Add Class...
  2. Set the Name to Course and click Add
  3. Change the file as follows:
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace SchoolCatalog1
    {
        [Serializable]
        public class Course
        {
            public string CourseCode;
            public string CourseName;
            public int    Credits;
        }
    }
  4. On the main menu, click Windows -> SchoolCatalog.cs [Design]*
  5. Double-click an unoccupied area of the form
  6. Change the file as follows:
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Runtime.Serialization.Formatters.Binary;
    
    namespace SchoolCatalog1
    {
        public partial class SchoolCatalog : Form
        {
            List<Course> courses;
    
            public SchoolCatalog()
            {
                InitializeComponent();
            }
    
            private void SchoolCatalog_Load(object sender, EventArgs e)
            {
                courses = new List<Course>();
            }
        }
    }
  7. Return to the form

De-Serialization

As serialization is the process of storing an object to a medium, the opposite, serialization is used to retrieve an object from a stream. To support this, the BinaryFormatter class is equipped with the Deserialize() method. Like Serialize(), the Deserialize() method is overloaded with two versions. One of them uses the following syntax:

public object Deserialize(Stream serializationStream);

This method takes as argument a Stream-based object, such as a FileStream variable, that indicates where the file is located. The Deserialize() method returns an Object object. As a goal, you want the Deserialize() method to produce the type of object that was saved so you can retrieve the values that the returned object holds. Because the method returns an Object value, you must cast the returned value to the type of your class.

Once the Deserialize() method has returned the desired object, you can access its values. Here is an example:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace Cars1
{
    public partial class Exercise : Form
    {
        public Exercise()
        {
            InitializeComponent();
        }

        private void btnWrite_Click(object sender, EventArgs e)
        {
            Car vehicle = new Car();
            vehicle.Make  = txtMake.Text;
            vehicle.Model = txtModel.Text;
            vehicle.Year  = uint.Parse(txtYear.Text);
            vehicle.Color = txtColor.Text;

            FileStream stmCar = new FileStream("Car3.car",
                                             FileMode.Create);
            BinaryFormatter bfmCar = new BinaryFormatter();

            bfmCar.Serialize(stmCar, vehicle);
        }

        private void btnRead_Click(object sender, EventArgs e)
        {
            FileStream stmCar = new FileStream("Car3.car",
                                             FileMode.Open);
            BinaryFormatter bfmCar = new BinaryFormatter();
            Car vehicle = (Car)bfmCar.Deserialize(stmCar);

            txtMake.Text = vehicle.Make;
            txtModel.Text = vehicle.Model;
            txtYear.Text = vehicle.Year.ToString();
            txtColor.Text = vehicle.Color;
        }
    }
}

Practical Learning: De-Serializing an Object

  1. On the form, double-click New Course...
  2. Return to the form and double-click the Close button
  3. Change the file as follows:
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Runtime.Serialization.Formatters.Binary;
    
    namespace SchoolCatalog1
    {
        public partial class SchoolCatalog : Form
        {
            List<Course> courses;
    
            public SchoolCatalog()
            {
                InitializeComponent();
            }
    
            private void SchoolCatalog_Load(object sender, EventArgs e)
            {
                courses = new List<Course>();
                ShowCourses();
            }
    
            private void ShowCourses()
            {
                // Get a reference to the file that holds the courses
                string Filename = @"C:\School Catalog\courses.sct";
    
                // Make sure the file exists
                if (File.Exists(Filename) == true)
                {
                    // if so, create a file stream
                    FileStream stmCourses = new FileStream(Filename,
                                                           FileMode.Open,
                                                           FileAccess.Read);
                    // Create a binary formatter
                    BinaryFormatter bfmCourse = new BinaryFormatter();
                    // If some courses were created already,
                    // get them and store them in the collection
                    courses = (List<Course>)bfmCourse.Deserialize(stmCourses);
    
                    // Prepare to show the list of courses
                    int i = 0;
                    // First, empty the data grid view
                    dgvCourseCataglog.Rows.Clear();
    
                    // Visit each course in the collection and add it to the data grid view
                    foreach (Course study in courses)
                    {
                        dgvCourseCataglog.Rows.Add();
    
                        dgvCourseCataglog.Rows[i].Cells[0].Value = study.CourseCode;
                        dgvCourseCataglog.Rows[i].Cells[1].Value = study.CourseName;
                        dgvCourseCataglog.Rows[i].Cells[2].Value = study.Credits.ToString();
                        i++;
                    }
    
                    // Close the file stream
                    stmCourses.Close();
                }
            }
    
            private void btnNewCourse_Click(object sender, EventArgs e)
            {
                // Get a reference to the course editor
                CourseEditor editor = new CourseEditor();
                // Check that the directory that contains the list of courses exists.
                // If it doesn't exist, create it
                DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\School Catalog");
                // Get a reference to the file that holds the courses
                string Filename = @"C:\School Catalog\courses.sct";
    
                // First check if the file was previously created
                if (File.Exists(Filename) == true)
                {
                    // If the list of courses exists already,
                    // get it and store it in a file stream
                    FileStream stmCourses = new FileStream(Filename,
                                                           FileMode.Open,
                                                           FileAccess.Read);
                    BinaryFormatter bfmCourse = new BinaryFormatter();
                    // Store the list of courses in the collection
                    courses = (List<Course>)bfmCourse.Deserialize(stmCourses);
                    // Close the file stream
                    stmCourses.Close();
                }
    
                // Display the Course Editor
                if (editor.ShowDialog() == DialogResult.OK)
                {
                    // Get each value of the new course.
                    // Create a Course object from it
                    Course study = new Course();
                    study.CourseCode = editor.txtCourseCode.Text;
                    study.CourseName = editor.txtCourseName.Text;
                    study.Credits    = int.Parse(editor.txtCredits.Text);
                    // Add the course in the collection
                    courses.Add(study);
    
                    // Get a reference to the courses file
                    string strFilename = dirInfo.FullName + "\\courses.sct";
                    // Create a file stream to hold the list of courses
                    FileStream stmCourses = new FileStream(strFilename,
                                                              FileMode.Create,
                                                              FileAccess.Write);
                    BinaryFormatter bfmCourses = new BinaryFormatter();
    
                    // Serialize the list of courses
                    bfmCourses.Serialize(stmCourses, courses);
                    // Close the file stream
                    stmCourses.Close();
                }
    
                // Show the list of courses
                ShowCourses();
            }
    
            private void btnClose_Click(object sender, EventArgs e)
            {
                Close();
            }
        }
    }
  4. Execute the application and continuously click the New Course button to create the following courses:
     
    School Catalog
     
    Course Code Course Name Credits
    CMSC 101 Introductory Computer Science 3
    ENGL 101 Introduction to English 3
    BMGT 324 Introduction to Entrepreneurship: Starting a Small Business 1
    BIOL 160 Human Biology 3
    BMGT 110 Introduction to Business and Management 3
    CMSC 150 Introduction to Discrete Structures 3
    CMSC 330 Advanced Programming Languages 3
    CHEM 121 Chemistry in the Modern World 3
     
    School Catalog

  5. Close the form and return to your programming environment
 
 
 

SOAP Serialization

 

Introduction

The .NET Framework supports another technique of serialization referred to as SOAP (which stands for Simple Object Access Protocol). This technique is related to XML but, although we haven't studied XML, you don't need to know anything about it to use SOAP serialization.

Practical Learning: Introducing SOAP Serialization

  1. Create a Windows Forms Application named RealEstate1
  2. To create a new form, on the main menu, click Projects -> Add Windows Form...
  3. Set the Name to PropertyEditor
  4. Click Add
  5. Design the form as follows:
     
    Real Estate
    Control (Name) BorderStyle DialogResult Enabled Text Modifiers
    Label Label         Property #:  
    TextBox Text Box txtPropertyNumber     False   Public
    Label Label         Market Value:  
    TextBox Text Box txtMarketValue       0.00 Public
    Label Label         Property Type:  
    TextBox Text Box txtPropertyTypes          Public
    Label Label         City:  
    TextBox Text Box txtCity         Public
    Label Label         State:  
    TextBox Text Box cbxStates         Public
    Label Label         Bedrooms:  
    TextBox Text Box txtBedrooms       0 Public
    Label Label         Bathrooms:  
    TextBox Text Box txtBathrooms       0.00 Public
    Button btnOK   OK   OK  
    Button btnCancel   Cancel   Cancel  
    Form
    FormBorderStyle: FixedDialog
    Text: Altair Realtors - Property Editor
    StartPosition: CenterScreen
    AcceptButton: btnOK
    CancelButton: btnCancel
    MaximizeBox: False
    MinimizeBox: False
    ShowInTaskBar: False
  6. In the Solution Explorer, right-click Form1.cs and click Rename
  7. Type AltairRealtor.cs and press Enter twice (to display that form)
  8. Design the form as follows:
     
    Altair Realtors
    Control (Name) Anchor Text
    DataGridView Data Grid View dgvProperties Top, Bottom, Left, Right  
    Columns  
    Header Text Name Width
    Prop# PropertyNumber 80
    Property Type PropertyType 120
    City City  
    State State 50
    Beds Bedrooms 50
    Bathrooms Bathrooms 50
    Market Value MarketValue  
    Button btnNewProperty Bottom, Left btnNewProperty
    Button Close Bottom, Right btnClose
    Form
    Text: Altair Realtors - Properties Listing
    StartPosition: CenterScreen

Serialization With SOAP

To serialize an object using SOAP, you follow the same steps we reviewed for the binary serialization with one addition: you must add a certain reference.

When creating the class whose objects would be serialized, mark it with the [Serializable] attribute. Here is an example:

[Serializable]
public class Car
{
    public string Make;
    public string Model;
    public uint   Year;
    public byte Color;
}

To support SOAP serialization, the .NET Framework provides the SoapFormatter class. This class is defined in the System.Runtime.Serialization.Formatters.Soap namespace that is part of the System.Runtime.Serialization.Formatters.Soap.dll assembly. In order to use The SoapFormatter class, you must reference this assembly. Then, you can create an object and initialize it as you see fit. Before saving it, as always, create a Stream-based object that would indicate the name (and location) of the file and the type of action to perform. Then, declare a SoapFormatter variable using its default constructor. To actually save the object, call the Serialize() method of this class. This method uses the same syntax as that of the BinaryFormatter class: it takes two arguments. The first is a Stream-based object. The second is the object that needs to be serialized.

Practical Learning: Serializing With SOAP

  1. To create a new class, on the main menu, click PROJECT -> Add Class...
  2. Set the Name to EstateProperty
  3. Click Add
  4. Change the file as follows:
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace RealEstate1
    {
        [Serializable]
        public class EstateProperty
        {
            public string PropertyNumber;
            public string PropertyType;
            public string City;
            public string State;
            public short Bedrooms;
            public float Bathrooms;
            public double MarketValue;
        }
    }
  5. To add SOAP support to your project, on the main menu, click PROJECT -> Add Reference...
  6. In the Add Reference dialog box and in the .NET tab, scroll down and select System.Runtime.Serialization.Formatters.Soap:
     
    Adding a reference to the System.Runtime.Serialization.Formatters.Soap.dll assembly
  7. Click OK
  8. On the main menu, click Windows -> AltairRealtors.cs [Design]*
  9. Double-click an unoccupied area of the form
  10. Change the file as follows:
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Runtime.Serialization.Formatters.Soap;
    
    namespace RealEstate1
    {
        public partial class AltairRealtor : Form
        {
            ArrayList properties;
    
            public AltairRealtor()
            {
                InitializeComponent();
            }
    
            private void AltairRealtor_Load(object sender, EventArgs e)
            {
                properties = new ArrayList();
        	    ShowProperties();
            }
    
            private void ShowProperties()
            {
            }
        }
    }
  11. Return to the form

De-Serialization With SOAP

De-serialization in soap is performed exactly as done for the binary de-serialization. To support it, the SoapFormatter class is equipped with the Deserialize() method. This method uses the same syntax as its equivalent of the BinaryFormatter class. The approach to use it is also the same.

Practical Learning: Deserializing With SOAP

  1. On the form, double-click New Property...
  2. Return to the form and double-click the Close button
  3. Change the file as follows:
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Runtime.Serialization.Formatters.Soap;
    
    namespace RealEstate1
    {
        public partial class AltairRealtor : Form
        {
            ArrayList properties;
    
            public AltairRealtor()
            {
                InitializeComponent();
            }
    
            private void AltairRealtor_Load(object sender, EventArgs e)
            {
                properties = new ArrayList();
                ShowProperties();
            }
    
            private void ShowProperties()
            {
                // Get a reference to the file that holds the records of properties
                string Filename = @"C:\Altair Realtors\properties.prp";
    
                // Make sure the file exists
                if (File.Exists(Filename) == true)
                {
                    // if so, create a file stream
                    FileStream stmProperties = new FileStream(Filename,
                                                              FileMode.Open,
                                                              FileAccess.Read);
                    // Create a soap formatter
                    SoapFormatter bfmProperty = new SoapFormatter();
                    // If some properties were created already,
                    // get them and store them in the collection
                    properties = (ArrayList)bfmProperty.Deserialize(stmProperties);
    
                    // Prepare to show the list of properties
                    int i = 0;
                    // First, empty the data grid view
                    dgvProperties.Rows.Clear();
    
                    // Visit each property in the collection and add it to the data grid view
                    foreach (EstateProperty house in properties)
                    {
                        dgvProperties.Rows.Add();
    
                        dgvProperties.Rows[i].Cells[0].Value = house.PropertyNumber;
                        dgvProperties.Rows[i].Cells[1].Value = house.PropertyType;
                        dgvProperties.Rows[i].Cells[2].Value = house.City;
                        dgvProperties.Rows[i].Cells[3].Value = house.State;
                        dgvProperties.Rows[i].Cells[4].Value = house.Bedrooms.ToString();
                        dgvProperties.Rows[i].Cells[5].Value = house.Bathrooms.ToString("F");
                        dgvProperties.Rows[i].Cells[6].Value = house.MarketValue.ToString("F");
                        i++;
                    }
    
                    // Close the file stream
                    stmProperties.Close();
                }
            }
    
            private void btnNewProperty_Click(object sender, EventArgs e)
            {
                // Get a reference to the property editor
                PropertyEditor editor = new PropertyEditor();
                // Check that the directory that contains the list of properties exists.
                // If it doesn't exist, create it
                DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Altair Realtors");
                // Get a reference to the file that holds the properties
                string Filename = @"C:\Altair Realtors\properties.prp";
    
                // First check if the file was previously created
                if (File.Exists(Filename) == true)
                {
                    // If the list of properties exists already,
                    // get it and store it in a file stream
                    FileStream stmProperties = new FileStream(Filename,
                                                              FileMode.Open,
                                                              FileAccess.Read);
                    SoapFormatter bfmProperty = new SoapFormatter();
                    // Store the list of properties in the collection
                    properties = (ArrayList)bfmProperty.Deserialize(stmProperties);
                    // Close the file stream
                    stmProperties.Close();
                }
    
                // Generate a random number for a property
                Random rnd = new Random();
                int left = rnd.Next(100, 999);
                int right = rnd.Next(100, 999);
                editor.txtPropertyNumber.Text = left.ToString() + "-"
                                                + right.ToString();
    
                // Display the Property Editor
                if (editor.ShowDialog() == DialogResult.OK)
                {
                    // Get each value of the new property.
                    // Create an EstateProperty object from it
                    EstateProperty prop = new EstateProperty();
                    prop.PropertyNumber = editor.txtPropertyNumber.Text;
                    prop.PropertyType = editor.txtPropertyType.Text;
                    prop.City = editor.txtCity.Text;
                    prop.State = editor.txtState.Text;
                    prop.Bedrooms = short.Parse(editor.txtBedrooms.Text);
                    prop.Bathrooms = float.Parse(editor.txtBathrooms.Text);
                    prop.MarketValue = double.Parse(editor.txtMarketValue.Text);
                    // Add the property in the collection
                    properties.Add(prop);
    
                    // Get a reference to the properties file
                    string strFilename = dirInfo.FullName + "\\properties.prp";
                    // Create a file stream to hold the list of properties
                    FileStream stmProperties = new FileStream(strFilename,
                                                              FileMode.Create,
                                                              FileAccess.Write);
                    SoapFormatter bfmProperty = new SoapFormatter();
    
                    // Serialize the list of properties
                    bfmProperty.Serialize(stmProperties, properties);
                    // Close the file stream
                    stmProperties.Close();
                }
    
                // Show the list of properties
                ShowProperties();
            }
    
            private void btnClose_Click(object sender, EventArgs e)
            {
                Close();
            }
        }
    }
  4. Execute the application and continuously click the New Property button to create the following properties (let the computer specify the property number):
     
    Real Estate
     
    Market Value Property Type City State  Beds Baths
    375650 Single Family Baltimore MD 5 3.50
    275500 Townhouse Gettysburg WV 3 2.50
    488665 Condominium Washington DC 1 1.00
    385000 Single Family Martinsburg WV 4 3.50
    568445 Condominium Rockville MD 1 1.00
     
    Real Estate
  5. Close the form and return to your programming environment

Details on Serialization

 

Partial Serialization

In the examples we have used so far, we were saving the whole object. You can make it possible to save only some parts of the class. When creating a class, you can specify what fields would be serialized and which ones would not be. To specify that a member cannot be saved, you can mark it with the [NonSerialized] attribute. Here is an example:

[Serializable]
public class Car
{
    public string Make;
    public string Model;

    // Because the value of a car can change,
    // there is no reason to save it
    [NonSerialized]
    public decimal Value;
    public uint Year;
    public byte Color;
}

After creating the class, you can declare a variable of it and serialize it, using either the binary or the SOAP approach. You can then retrieve the object and its values, using any of the techniques we learned earlier.

Implementing a Custom Serialized Class

To support serialization, the .NET Framework provides the ISerializable interface. You can create a class that implements this interface to customize the serialization process. Even if you plan to use this interface, the class you create must be marked with the [Serializable] attribute.

.NET Built-In Serialized Classes

The .NET Framework is filled with many classes ready for serialization. To know that a class is ready for serialization, when viewing its documentation either in the MSDN web site or in the help documentation, check that it is marked with the [SerializableAttribute]. Here is an example of such as class:

The Serializable attribute of a built-in class

Some of these classes provide the properties and methods to create an object and directly save it. For some other classes, you must first create a class, mark it with the [Serializable] attribute, build an object of it, and then pass it to the .NET class.

 
 
   
 

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