Data Bound Applications with ADO.NET and Custom Objects

[Vanessa]

Hi all!

I was reading this article about data binding:

http://msdn2.microsoft.com/en-us/magazine/cc163477.aspx

I have a question: if I add a new property (ContactName, for example) to
Customer class and add a TextBox (readonly), how can I bind it? What I want
is: when I change the Customer on the ComboBox (or select another item on the
DataGridView), I’d like to update the TextBox ContactName.

Thank you,

Vanessa

 

[Marc Gravell]

Well, you should be able to just use standard binding. It should appear in
the list if you use the IDE. The trick is to use the same instance as the
data-source for both the list (datagridview, etc) and the single item
(textbox etc):

(note I haven't used notifications here for brevity)

using System;
using System.Windows.Forms;
using System.ComponentModel;
class Foo
{
public string Name { get; set; }
public DateTime DateOfBirth { get; set; }
}
static class Program
{
static void Main()
{
Application.EnableVisualStyles();
BindingList<Foo> list = new BindingList<Foo> {
new Foo {Name="Fred", DateOfBirth=DateTime.Today},
new Foo {Name="Jo", DateOfBirth=DateTime.Today.AddDays(-20)}
};
using(DataGridView dgv = new DataGridView {
Dock = DockStyle.Fill,
DataSource = list
})
using(TextBox txt = new TextBox {
Dock = DockStyle.Bottom,
ReadOnly = true
})
using (Form form = new Form
{
Controls = { dgv, txt }
})
{
txt.DataBindings.Add("Text", list, "Name");
//form.DataBindings.Add("Text", list, "Name");
Application.Run(form);
}
}
}

 

[Claire]

You'd bind the textbox to the same field as the field in the datagridview.
The textbox will update to reflect changes once the record is posted

class clsServerInfo
{
public string Address
{
get
{
return _address;
}
set
{
_address = value;
}
}
}// end class

clsServerInfo ServerInfo = new clsServerInfo();

// bind the "Text" property of textbox txtAddress to
// the contents of ServerInfo.Address
txtAddress.DataBindings.Add("Text", ServerInfo, "Address");

 

[Vanessa]

Hi Marc!

Thank you for your answer, but my question is about binding from another
level (I think).

In the sample there is a datagridview where the datasource is from an order
list. On the right side it is shown some fields in a form, like customer
name, employee, and other fields from order list. The customer name is a
combobox that is binding from a list of customers, but it is related to
customer ID that is on the order list. What I want is to show another
property from customer in a textbox, or in other words, just a textbox to
show more information about the customer.

Thank you,
Vanessa

 

[Vanessa]

Hi Claire!

Thank you for your answer, but my question is about binding from another
level (I think).

In the sample there is a datagridview where the datasource is from an order
list. On the right side it is shown some fields in a form, like customer
name, employee, and other fields from order list. The customer name is a
combobox that is binding from a list of customers, but it is related to
customer ID that is on the order list. What I want is to show another
property from customer in a textbox, or in other words, just a textbox to
show more information about the customer.

Thank you,
Vanessa

 

[Marc Gravell]

Do you mean like this?

using System;
using System.Windows.Forms;
using System.ComponentModel;
class Order
{
public int OrderId { get; set; }
public string YourRef { get; set; }
public string OurRef { get; set; }
public Customer Customer { get; set; }
public override string ToString()
{
return OurRef;
}

}
class Customer
{
public string Name { get; set; }
public string Address { get; set; }
public int CustomerId { get; set; }
public override string ToString()
{
return Name;
}
}
static class Program
{
static void Main()
{
Application.EnableVisualStyles();

var customers = new BindingList<Customer>
{
new Customer {CustomerId = 1, Name = "Fred", Address =
"Somewhere"},
new Customer {CustomerId = 2, Name = "Barney", Address =
"Somewhere else"},
};
var orders = new BindingList<Order>
{
new Order {OrderId = 1, OurRef = "001", YourRef = "abc",
Customer = customers[0]},
new Order {OrderId = 2, OurRef = "002", YourRef = "def",
Customer = customers[1]},
new Order {OrderId = 3, OurRef = "003", YourRef = "ghi",
Customer = customers[0]},
new Order {OrderId = 4, OurRef = "004", YourRef = "jkl",
Customer = customers[1]}
};


using (Form form = new Form
{
Controls = {
new DataGridView {
Dock = DockStyle.Fill,
DataSource = orders
},
new TextBox {
Dock = DockStyle.Bottom,
ReadOnly = true,
DataBindings =
{
{"Text",customers,"Address"}
}
},
new ComboBox {
Dock = DockStyle.Bottom,
DropDownStyle = ComboBoxStyle.DropDownList,
DataSource = customers,
DisplayMember = "Name",
DataBindings =
{
{"SelectedItem", orders, "Customer"}
}
}
}
})
{
Application.Run(form);
}
}
}

 

[Marc Gravell]

Note - if the order has a CustomerId, not a Customer (i.e. you want to match
by matching a key, not by object reference) - then:

new ComboBox {
Dock = DockStyle.Bottom,
DropDownStyle = ComboBoxStyle.DropDownList,
DataSource = customers,
DisplayMember = "Name",
ValueMember = "CustomerId",
DataBindings = {
{"SelectedValue", orders, "CustomerId"}
}
}

You don't need to change the textbox, since that is simply bound to the list
of customers, with the current row selected automatically via sharing a
currency-manager with the combobox.

Marc

 

[Vanessa]

Thank you Marc!
That is exactly what I need!
Vanessa

 

[Vanessa]

Hi Marc!

Your example worked like I wanted, but now I need to go ahead.

Imagine that I have a list of cities and every customer has a city ID. It is
like this:

class Customer
{
public string Name { get; set; }
public string Address { get; set; }
public int CityId { get; set; } ======> I added this property
public int CustomerId { get; set; }
public override string ToString()
{
return Name;
}
}

class City
{
public string Name { get; set; }
public string State { get; set; }
public int CityId { get; set; }
public override string ToString()
{
return Name;
}
}

So, in your example, I need to add info about the city of the customer. It
could be a combobox with the city name and a textbox with the state. How can
I bind this level?

Thank you,
Vanessa

 

[Vanessa]

Hi Marc!

Please forget the last question, I already did it and it is working well.

I just have a doubt: how can I clear the combos and textboxes when I click
on the last row? Or, if I apply a filter on the datagridview and there will
be no rows on it?

Thank you!
Vanessa