Question

I’m trying to implement a Load / Save function for a Windows Forms application.

I’ve got following components:

• A tree view
• A couple of list views
• A couple of text boxes
• A couple of objects (which holds a big dictionarylist)

I want to implement a way to save all of this into a file, and resume/load it later on.

What’s the best way to do this?

I think XML serialization is the way to go, but I’m not quite sure how, or where to start. Or will it require a really complex solution to be able to do this?

Answer 1

Here’s an example that binds an object and some ancestors to the UI; the use of C# 3.0 here is purely for brevity – everything would work with C# 2.0 too.

Most of the code here is setting up the form, and/or dealing with property-change notifications – importantly, there isn’t any code devoted to updating the UI from the object model, or the object model from the UI.

Note also the IDE can do a lot of the data-binding code for you, simply by dropping a BindingSource onto the form and setting the DataSource to a type via the dialog in the property grid.

Note that it isn’t essential to provide property change notifications (the PropertyChanged stuff) – however, most 2-way UI binding will work considerably better if you do implement this. Not that PostSharp has some interesting ways of doing this with minimal code.

using System; using System.Collections.Generic; using System.ComponentModel; using System.IO; using System.Windows.Forms; using System.Xml.Serialization; static class Program { // formatted for vertical space     [STAThread]     static void Main() {         Application.EnableVisualStyles();          Button load, save, newCust;         BindingSource source = new BindingSource { DataSource = typeof(Customer) };         XmlSerializer serializer = new XmlSerializer(typeof(Customer));         using (Form form = new Form {             DataBindings = {{'Text', source, 'Name'}}, // show customer name as form title             Controls = {                 new DataGridView { Dock = DockStyle.Fill, // grid of orders                     DataSource = source, DataMember = 'Orders'},                 new TextBox { Dock = DockStyle.Top, ReadOnly = true, // readonly order ref                     DataBindings = {{'Text', source, 'Orders.OrderRef'}}},                 new TextBox { Dock = DockStyle.Top, // editable customer name                     DataBindings = {{'Text', source, 'Name'}}},                 (save = new Button { Dock = DockStyle.Bottom, Text = 'save' }),                 (load = new Button{ Dock = DockStyle.Bottom, Text = 'load'}),                 (newCust = new Button{ Dock = DockStyle.Bottom, Text = 'new'}),                }         })         {             const string PATH = 'customer.xml';             form.Load += delegate {                 newCust.PerformClick(); // create new cust when loading form                 load.Enabled = File.Exists(PATH);             };             save.Click += delegate {                 using (var stream = File.Create(PATH)) {                     serializer.Serialize(stream, source.DataSource);                 }                 load.Enabled = true;             };             load.Click += delegate {                 using (var stream = File.OpenRead(PATH)) {                     source.DataSource = serializer.Deserialize(stream);                 }             };             newCust.Click += delegate {                 source.DataSource = new Customer();             };             Application.Run(form);         }      } }  [Serializable] public sealed class Customer : NotifyBase {     private int customerId;     [DisplayName('Customer Number')]     public int CustomerId {         get { return customerId; }         set { SetField(ref customerId, value, 'CustomerId'); }     }      private string name;     public string Name {         get { return name; }         set { SetField(ref name, value, 'Name'); }     }      public List<Order> Orders { get; set; } // XmlSerializer demands setter      public Customer() {         Orders = new List<Order>();     } }  [Serializable] public sealed class Order : NotifyBase {     private int orderId;     [DisplayName('Order Number')]     public int OrderId  {         get { return orderId; }         set { SetField(ref orderId, value, 'OrderId'); }     }      private string orderRef;     [DisplayName('Reference')]     public string OrderRef {         get { return orderRef; }         set { SetField(ref orderRef, value, 'OrderRef'); }     }      private decimal orderValue, carriageValue;      [DisplayName('Order Value')]     public decimal OrderValue {         get { return orderValue; }         set {             if (SetField(ref orderValue, value, 'OrderValue')) {                 OnPropertyChanged('TotalValue');             }         }     }      [DisplayName('Carriage Value')]     public decimal CarriageValue {         get { return carriageValue; }         set {             if (SetField(ref carriageValue, value, 'CarriageValue')) {                 OnPropertyChanged('TotalValue');             }         }     }      [DisplayName('Total Value')]     public decimal TotalValue { get { return OrderValue + CarriageValue; } } }  [Serializable] public class NotifyBase { // purely for convenience     [field: NonSerialized]     public event PropertyChangedEventHandler PropertyChanged;      protected bool SetField<T>(ref T field, T value, string propertyName) {         if (!EqualityComparer<T>.Default.Equals(field, value)) {             field = value;             OnPropertyChanged(propertyName);             return true;         }         return false;     }     protected virtual void OnPropertyChanged(string propertyName) {         PropertyChangedEventHandler handler = PropertyChanged;         if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));     } }