Bind objects as data sources in Visual Studio

Applies to: Visual Studio Visual Studio for Mac

Visual Studio provides design-time tools for working with custom objects as the data source in your application. When you want to store data from a database in an object that you bind to UI controls, the recommended approach is to use Entity Framework to generate the class or classes. Entity Framework auto-generates all the boilerplate change-tracking code, which means that any changes to the local objects are automatically persisted to the database when you call AcceptChanges on the DbSet object. For more information, see Entity Framework Documentation.

Object requirements

The only requirement for custom objects to work with the data design tools in Visual Studio is that the object needs at least one public property.

Generally, custom objects do not require any specific interfaces, constructors, or attributes to act as a data source for an application. However, if you want to drag the object from the Data Sources window to a design surface to create a data-bound control, and if the object implements the ITypedList or IListSource interface, the object must have a default constructor. Otherwise, Visual Studio cannot instantiate the data source object, and it displays an error when you drag the item to the design surface.

Examples of using custom objects as data sources

While there are countless ways to implement your application logic when working with objects as a data source, for SQL databases there are a few standard operations that can be simplified by using the Visual Studio-generated TableAdapter objects. This page explains how to implement these standard processes using TableAdapters. It is not intended as a guide for creating your custom objects. For example, you will typically perform the following standard operations regardless of the specific implementation of your objects, or application's logic:

• Loading data into objects (typically from a database).

• Creating a typed collection of objects.

• Adding objects to and removing objects from a collection.

• Displaying the object data to users on a form.

• Changing/editing the data in an object.

• Saving data from objects back to the database.

Load data into objects

For this example, you load data into your objects by using TableAdapters. By default, TableAdapters are created with two kinds of methods that fetch data from a database and populate data tables.

• The TableAdapter.Fill method fills an existing data table with the data returned.

• The TableAdapter.GetData method returns a new data table populated with data.

The easiest way to load your custom objects with data is to call the TableAdapter.GetData method, loop through the collection of rows in the returned data table, and populate each object with the values in each row. You can create a GetData method that returns a populated data table for any query added to a TableAdapter.

The following example shows how to loop through the rows in a data table, and populate an object with data:

private void LoadCustomers()
{
    NorthwindDataSet.CustomersDataTable customerData = 
        customersTableAdapter1.GetTop5Customers();
    
    foreach (NorthwindDataSet.CustomersRow customerRow in customerData)
    {
        Customer currentCustomer = new Customer();
        currentCustomer.CustomerID = customerRow.CustomerID;
        currentCustomer.CompanyName = customerRow.CompanyName;

        if (customerRow.IsAddressNull() == false)
        {
            currentCustomer.Address = customerRow.Address;
        }

        if (customerRow.IsCityNull() == false)
        {
            currentCustomer.City = customerRow.City;
        }

        if (customerRow.IsContactNameNull() == false)
        {
            currentCustomer.ContactName = customerRow.ContactName;
        }

        if (customerRow.IsContactTitleNull() == false)
        {
            currentCustomer.ContactTitle = customerRow.ContactTitle;
        }

        if (customerRow.IsCountryNull() == false)
        {
            currentCustomer.Country = customerRow.Country;
        }

        if (customerRow.IsFaxNull() == false)
        {
            currentCustomer.Fax = customerRow.Fax;
        }

        if (customerRow.IsPhoneNull() == false)
        {
            currentCustomer.Phone = customerRow.Phone;
        }

        if (customerRow.IsPostalCodeNull() == false)
        {
            currentCustomer.PostalCode = customerRow.PostalCode;
        }

        if (customerRow.IsRegionNull() == false)
        {
            currentCustomer.Region = customerRow.Region;
        }

        LoadOrders(currentCustomer);
        customerBindingSource.Add(currentCustomer);
    }
}

Private Sub LoadCustomers()
    Dim customerData As NorthwindDataSet.CustomersDataTable =
        CustomersTableAdapter1.GetTop5Customers()

    Dim customerRow As NorthwindDataSet.CustomersRow

    For Each customerRow In customerData
        Dim currentCustomer As New Customer()
        With currentCustomer

            .CustomerID = customerRow.CustomerID
            .CompanyName = customerRow.CompanyName

            If Not customerRow.IsAddressNull Then
                .Address = customerRow.Address
            End If

            If Not customerRow.IsCityNull Then
                .City = customerRow.City
            End If

            If Not customerRow.IsContactNameNull Then
                .ContactName = customerRow.ContactName
            End If

            If Not customerRow.IsContactTitleNull Then
                .ContactTitle = customerRow.ContactTitle
            End If

            If Not customerRow.IsCountryNull Then
                .Country = customerRow.Country
            End If

            If Not customerRow.IsFaxNull Then
                .Fax = customerRow.Fax
            End If

            If Not customerRow.IsPhoneNull Then
                .Phone = customerRow.Phone
            End If

            If Not customerRow.IsPostalCodeNull Then
                .PostalCode = customerRow.PostalCode
            End If

            If Not customerRow.Is_RegionNull Then
                .Region = customerRow._Region
            End If

        End With

        LoadOrders(currentCustomer)
        CustomerBindingSource.Add(currentCustomer)
    Next
End Sub

Create a typed collection of objects

You can create collection classes for your objects, or use the typed collections that are automatically provided by the BindingSource component.

When you're creating a custom collection class for objects, we suggest that you inherit from BindingList<T>. This generic class provides functionality to administer your collection, as well as the ability to raise events that send notifications to the data-binding infrastructure in Windows Forms.

The automatically generated collection in the BindingSource uses a BindingList<T> for its typed collection. If your application does not require additional functionality, you can maintain your collection within the BindingSource. For more information, see the List property of the BindingSource class.

The following code shows how to create the class for a strongly-typed collection of Order objects:

/// <summary>
/// A collection of Orders
/// </summary>
public class Orders: System.ComponentModel.BindingList<Order>
{
    // Add any additional functionality required by your collection.
}

''' <summary>
''' A collection of Orders
''' </summary>
Public Class Orders
    Inherits System.ComponentModel.BindingList(Of Order)

    ' Add any additional functionality required by your collection.

End Class

Add objects to a collection

You add objects to a collection by calling the Add method of your custom collection class or of the BindingSource.

The following code shows how to add objects to the typed collection in a BindingSource:

Customer currentCustomer = new Customer();
customerBindingSource.Add(currentCustomer);

Dim currentCustomer As New Customer()
CustomerBindingSource.Add(currentCustomer)

The following code shows how to add objects to a typed collection that inherits from BindingList<T>:

Order currentOrder = new Order();
currentCustomer.Orders.Add(currentOrder);

Dim currentOrder As New Order()
currentCustomer.Orders.Add(currentOrder)

Remove objects from a collection

You remove objects from a collection by calling the Remove or RemoveAt method of your custom collection class or of BindingSource.

The following code shows how to locate and remove objects from the typed collection in a BindingSource with the RemoveAt method:

int customerIndex = customerBindingSource.Find("CustomerID", "ALFKI");
customerBindingSource.RemoveAt(customerIndex);

Dim customerIndex As Integer = CustomerBindingSource.Find("CustomerID", "ALFKI")
CustomerBindingSource.RemoveAt(customerIndex)

Display object data to users

To display the data in objects to users, create an object data source using the Data Source Configuration wizard, and then drag the entire object or individual properties onto your form from the Data Sources window.

Modify the data in objects

To edit data in custom objects that are data-bound to Windows Forms controls, simply edit the data in the bound control (or directly in the object's properties). Data-binding architecture updates the data in the object.

If your application requires the tracking of changes and the rolling back of proposed changes to their original values, then you must implement this functionality in your object model. For examples of how data tables keep track of proposed changes, see DataRowState, HasChanges, and GetChanges.

Save data in objects back to the database

Save data back to the database by passing the values from your object to the TableAdapter's DBDirect methods.

Visual Studio creates DBDirect methods that can be executed directly against the database. These methods do not require DataSet or DataTable objects.

To save data from a collection of objects, loop through the collection of objects (for example, using a for-next loop). Send the values for each object to the database by using the TableAdapter's DBDirect methods.

The following example shows how to use the TableAdapter.Insert DBDirect method to add a new customer directly into the database:

private void AddNewCustomers(Customer currentCustomer)
{
    customersTableAdapter.Insert( 
        currentCustomer.CustomerID, 
        currentCustomer.CompanyName, 
        currentCustomer.ContactName, 
        currentCustomer.ContactTitle, 
        currentCustomer.Address, 
        currentCustomer.City, 
        currentCustomer.Region, 
        currentCustomer.PostalCode, 
        currentCustomer.Country, 
        currentCustomer.Phone, 
        currentCustomer.Fax);
}

Private Sub AddNewCustomer(ByVal currentCustomer As Customer)

    CustomersTableAdapter.Insert(
        currentCustomer.CustomerID,
        currentCustomer.CompanyName,
        currentCustomer.ContactName,
        currentCustomer.ContactTitle,
        currentCustomer.Address,
        currentCustomer.City,
        currentCustomer.Region,
        currentCustomer.PostalCode,
        currentCustomer.Country,
        currentCustomer.Phone,
        currentCustomer.Fax)
End Sub

See also

• Bind controls to data in Visual Studio