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Pass data between forms

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Datasets and related classes are legacy .NET Framework technologies from the early 2000s that enable applications to work with data in memory while the applications are disconnected from the database. The technologies are especially useful for applications that enable users to modify data and persist the changes back to the database. Although datasets have proven to be a very successful technology, we recommend that new .NET applications use Entity Framework Core. Entity Framework provides a more natural way to work with tabular data as object models, and it has a simpler programming interface.

This tutorial provides step-by-step instructions for passing data from one form to another. By using the Customers and Orders tables from the Northwind sample database, one form allows users to select a customer, and a second form displays the selected customer's orders. This tutorial shows how to create a method on the second form that receives data from the first form.

In this tutorial, you complete the following tasks:

  • Create a new Windows Forms App (.NET Framework) project.
  • Create and configure a dataset by using the Data Source Configuration Wizard.
  • Select the control to create on the form when you drag items from the Data Sources window. For more information, see Set the control to be created when dragging from the Data Sources window.
  • Create a data-bound control by dragging items from the Data Sources window onto a form.
  • Create a second form with a grid that displays data.
  • Create a TableAdapter query to fetch orders for a specific customer.
  • Pass data between forms.

Note

This tutorial demonstrates only one way to pass data between forms. There are other options for passing data to a form, such as creating a second constructor to receive data, or creating a public property that can be set with data from the first form.

Prerequisites

  • The .NET desktop development and Data storage and processing workloads installed in Visual Studio. To install them, open Visual Studio Installer and choose Modify, or More > Modify, next to the version of Visual Studio you want to use. For more information, see Modify Visual Studio.

  • SQL Server Express 2019 LocalDB installed either from the SQL Server downloads page, or through the Visual Studio Installer as part of the Data storage and processing workload.

  • The Northwind sample database, created by following these steps:

    1. In Visual Studio, open the SQL Server Object Explorer window by selecting it from the View menu. SQL Server Object Explorer is installed as part of the Data storage and processing workload.

    2. Expand the SQL Server node, right-click your LocalDB instance, and select New Query to open a query editor window.

    3. Copy the Northwind Transact-SQL script to your clipboard. This T-SQL script creates the Northwind database and populates it with data.

    4. Paste the T-SQL script into the query editor, and then select Execute at the top of the window to create the Northwind database.

Create the Windows Forms app project

  1. In Visual Studio, on the File menu, select New > Project.

  2. Select either C# or Visual Basic from the All languages dropdown list, Windows from the All platforms dropdown list, and Desktop from the All project types list.

  3. Select Windows Forms App (.NET Framework) from the project templates list, and then select Next.

  4. Name the project PassingDataBetweenForms, select Next, and then select Create.

The PassingDataBetweenForms project is created and added to Solution Explorer. The designer view of Form1 appears in the editor.

Create the data source

  1. Open the Data Sources window by selecting Project > Add New Data Source on the Visual Studio menu.

  2. In the Data Sources window, select Add New Data Source to start the Data Source Configuration wizard.

  3. On the Choose a Data Source Type page, select Database, and then select Next.

  4. On the Choose a Database Model page, verify that Dataset is specified and select Next.

  5. On the Choose Your Data Connection page, if a data connection to the Northwind sample database is already available, select it, and proceed to the Choose your Database Objects step. Otherwise, select New Connection.

  6. On the Choose Data Source screen, select Microsoft SQL Server Database File, and then select Continue.

  7. On the Add Connection screen, select Browse, browse to and select the northwnd.mdf file, and select Open.

  8. Either select Windows Authentication, or select SQL Server Authentication and supply a user name and password to access the database.

  9. Select Test Connection to test the connection. When the connection succeeds, select OK.

  10. On the Choose Your Data Connection page, confirm that the database file appears and select Next.

  11. Select No to the popup question Would you like to copy the file to your project and modify the connection?

  12. On the Save the Connection String to the Application Configuration file page, select Yes. Name the connection NorthwindConnectionString, and then select Next.

  13. On the Choose your Database Objects page, expand the Tables node, select the Customers and Orders tables, name the dataset NorthwindDataSet, and then select Finish.

The NorthwindDataSet is added to your project, and the Customers and Orders tables appear in the Data Sources window.

Populate the first form

Create the second form

Create a second form to pass data to.

  1. From the Project menu, choose Add Form (Windows Forms).

  2. Leave the default name of Form2, and select Add.

  3. Drag the main Orders node from the Data Sources window onto Form2.

    A DataGridView and a BindingNavigator tool strip for navigating records appear on Form2. A NorthwindDataSet, CustomersTableAdapter, BindingSource, and BindingNavigator appear in the component tray.

  4. Delete the OrdersBindingNavigator from the component tray. The BindingNavigator disappears from Form2.

Add a TableAdapter query

Add a TableAdapter query to Form2 that loads orders for the customer selected on Form1.

  1. Double-click the NorthwindDataSet.xsd file in Solution Explorer.

  2. Right-click OrdersTableAdapter in the Orders table, and select Add > Query.

  3. Leave the default option of Use SQL statements and select Next.

  4. Leave the default option of SELECT which returns rows and select Next.

  5. In What data should the table load, to return Orders based on the CustomerID, add a WHERE clause to the end of the query. The final query should look similar to the following code:

    SELECT OrderID, CustomerID, OrderDate, RequiredDate, ShippedDate, ShipVia, Freight, ShipName, ShipAddress, ShipCity, ShipRegion, ShipPostalCode, ShipCountry
FROM Orders
WHERE CustomerID = @CustomerID

    Note

    Use the correct parameter syntax for your database. For example, in Microsoft Access, the WHERE clause would look like WHERE CustomerID = ?.

  6. Select Next.

  7. On the Choose Methods to Generate screen, select Fill a DataTable and enter FillByCustomerID.

  8. Deselect the Return a DataTable option, and then select Finish.

Create a method on Form2 to pass data to

  1. Right-click in Form2 and select View Code to open the Form2 code in the editor.

  2. In the Form2 code, remove the contents of the Form2_Load method, and add the following code after the Form2_Load method:

internal void LoadOrders(String CustomerID)
{
    ordersTableAdapter.FillByCustomerID(northwindDataSet.Orders, CustomerID);
}

Create a method on Form1 to pass data and display Form2

  1. In the Designer view of Form1, right-click the Customer data grid, and then select Properties.

  2. In the Properties window, select the Events icon in the top toolbar.

  3. Double-click the DoubleClick event to open the code editor.

  4. In the code editor, update the method definition to match the following sample:

private void customersDataGridView_DoubleClick(object sender, EventArgs e)
{
    System.Data.DataRowView SelectedRowView;
    NorthwindDataSet.CustomersRow SelectedRow;

    SelectedRowView = (System.Data.DataRowView)customersBindingSource.Current;
    SelectedRow = (NorthwindDataSet.CustomersRow)SelectedRowView.Row;

    Form2 OrdersForm = new Form2();
    OrdersForm.LoadOrders(SelectedRow.CustomerID);
    OrdersForm.Show();
}

Run and test the app

  1. Press F5 to run the application.

  2. In the application, double-click a customer record in Form1 to open Form2 with that customer's orders.

Next steps

Depending on your application requirements, you can do several steps after passing data between forms. Some enhancements you could make to this tutorial include:

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