Using a BindingSource in a UserControl

Question

I have a UserControl with multiple fields that I would like to have bound to a BindingSource. I would also like the UserControl to expose some BindingSource property so that it can be dropped on a Form and be bound to the BindingSource on the form. Is there an easy way to do this? I realize that I can rebind all of the controls of the UserControl in its BindSource setter. But this seems wrong. Is there some BindingSource Proxy that will let me link the BindingSource in the user control to the BindingSource in the form?

Answer 1

As per your question, I can hardly get what you intend to do. Thus I will try my best to provide you with, I hope, interesting information on that matter.

First, let's consider the following UserControl in a Customer management software project.

public partial class CustomerManagementUserControl : UserControl {
    public CustomerManagementUserControl() {
        InitializeComponent();
        _customerBindingSource = new BindingSource();
    }
    public IList<ICustomer> DataSource {
        set {
            _customerBindingSource.DataSource = value;
        }
    }
    private BindingSource _customerBindingSource;
}

Second, let's consider the following Form which should be your Customer management form.

public partial class CustomerManagementForm : Form {
    public CustomerManagementForm() {
        InitializeComponent();
        _customerUserControl = new CustomerManagementUserControl();
        _customerUserControl.Name = @"customerUserControl";
    }
    private void CustomerManagementForm_Load(object sender, EventArgs e) {
        // CustomersFacade is simply a static class providing customer management features and requirements.
        // Indeed, the GetCustomers() method shall return an IList<ICustomer>.
        // The IList type and typed IList<T> are both intended to be bindable as a DataSource for DataBinding.
        _customerUserControl.DataSource = CustomersFacade.GetCustomers();
        this.Controls.Add(_customerUserControl);
    }
    private CustomerManagementUserControl _customerUserControl;
}

If you're expecting to use CustomerManagementUserControl.DataSource property from within the Property window, please consider adding the following on top of your property definition.

[System.ComponentModel.DesignTimeVisible(true), System.ComponentModel.DesignerCategory("CustomerUserControl"), System.ComponentModel.Description("Sets the CustomerUserControl DataSource property")]

This is one way of doing what I guess you might want to do. On the other hand, if what you wish to do is to get the as most abstract as possible by setting a different type of object as your UserControl.BindingSource.DataSource property, then you will have to write a method which could detect the type of the object passed, then binding the properties accordingly. A nice way you could go, perhaps, is by Reflection, if you're comfortable working with it. In any possible way you may imagine working with such polymorphism features, you will have to write yourself an interface that all of your bindable objects will have to implement. This way, you will avoid unknown property names, and when will come the time to bind your UserControl's controls, you will be able to bind the correct property to the correct control and so forth.

Let's try the following:

public interface IEntity {
    double Id { get; set; }
    string Number { get; set; }
    string Firstname { get; set; }
    string Surname { get; set; }
    long PhoneNumber { get; set; }
}
public interface ICustomer : IEntity {
}
public interface ISupplier : IEntity {
    string Term { get; set; }
}
public sealed Customer : ICustomer {
    public Customer() {
    }
    public double Id { get; set; }
    public string Number { get; set; }
    public string Firstname { get; set; }
    public string Surname { get; set; }
    public long PhoneNumber { get; set; }    
}
public sealed Supplier : ISupplier {
    public Supplier() {
    }
    public double Id { get; set; }
    public string Number { get; set; }
    public string Firstname { get; set; }
    public string Surname { get; set; }
    public long PhoneNumber { get; set; }    
    public string Term { get; set; }
}

Considering the above code, you could use the DataSource property of your UserControl to bind with an IEntity, so your property could like like this.

[System.ComponentModel.DesignTimeVisible(true), System.ComponentModel.DesignerCategory("CustomerUserControl"), System.ComponentModel.Description("Sets the CustomerUserControl DataSource property")]
public IList<IEntity> DataSource {
    set {
        _customerBindingSource.DataSource = value;
    }
}

That said, if you wish to push even further, you could just expose your UserControl's controls DataBindings properties in order to set them on design-time. Considering this, you will want to expose your BindingSource as a public property either so that you may set it on design-time too, then choose your DataMember from this BindinSource.

I hope this helps you both a little or at least, give you some tracks for further searchings.