Walkthrough: Passing Data Between Windows Forms

Artigo
04/28/2015

This walkthrough provides step-by-step instructions for passing data from one form to another. Using the customers and orders tables from Northwind one form will allow users to select a customer and a second form will display the selected customer's orders. This walkthrough shows how to create a method on one form that receives data from the first form.

Note

This walkthrough demonstrates only one way to pass data between forms. There are other options for passing data to a form, including these approaches: you can create a second constructor to receive data, or you can create a public property that can be set with data from the first form.

Tasks illustrated in this walkthrough include:

Creating a new Windows Application project.
Creating and configuring a dataset with the Data Source Configuration Wizard.
Selecting the control to be created on the form when dragging items from the Data Sources window. For more information, see How to: Set the Control to be Created when Dragging from the Data Sources Window.
Creating a data-bound control by dragging items from the Data Sources window onto a form.
Creating a second form with a grid to display data.
Creating a TableAdapter query to fetch orders for a specific customer.
Passing data between forms.

Prerequisites

In order to complete this walkthrough, you need:

Access to the Northwind sample database. For more information, see How to: Install Sample Databases.

Creating the Windows Application

To create the new Windows project

From the File menu, create a new project.
Name the project PassingDataBetweenForms.
Select Windows Forms Application and click OK. For more information, see Developing Client Applications with the .NET Framework.

The PassingDataBetweenForms project is created and added to Solution Explorer.

Creating the Data Source

To create the Data Source

On the Data menu, click Show Data Sources.
In the Data Sources window, select Add New Data Source to start the Data Source Configuration Wizard.
Select Database on the Choose a Data Source Type page, and then click Next.
On the Choose a database model page, verify that Dataset is specified, and then click Next.
On the Choose your Data Connection page, do one of the following:
- If a data connection to the Northwind sample database is available in the drop-down list, select it.
  
  -or-
- Select New Connection to launch the Add/Modify Connection dialog box.
If your database requires a password and if the option to include sensitive data is enabled, select the option and then click Next.
Click Next on the Save connection string to the Application Configuration file page.
Expand the Tables node on the Choose your Database Objects page.
Select the Customers and Orders tables, and then click Finish.

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

Creating the First Form (Form1)

You can create a data-bound grid (a DataGridView control) by dragging the Customers node from the Data Sources window onto the form.

To create a data-bound grid on the form

Drag the main Customers node from the Data Sources window onto Form1.

A DataGridView and a tool strip (BindingNavigator) for navigating records appear on Form1. A NorthwindDataSet, CustomersTableAdapter, BindingSource, and BindingNavigator appear in the component tray.

Creating the Second Form (Form2)

To create a second form to pass the data to

From the Project menu, choose Add Windows Form.
Leave the default name of Form2 and click Add.
Drag the main Orders node from the Data Sources window onto Form2.

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

The OrdersBindingNavigator disappears from Form2.

Adding a TableAdapter Query to Form2 to Load Orders for the Selected Customer on Form1

To create a TableAdapter Query

Double-click the NorthwindDataSet.xsd file in Solution Explorer.
Right-click the OrdersTableAdapter and select Add Query.
Leave the default option of Use SQL statements, and then click Next.
Leave the default option of SELECT which returns rows, and then click Next.
Add a WHERE clause to the query to return Orders based on the CustomerID. The query should be similar to the following:
```
SELECT OrderID, CustomerID, EmployeeID, OrderDate, RequiredDate, ShippedDate, ShipVia, Freight, ShipName, ShipAddress, ShipCity, ShipRegion, ShipPostalCode, ShipCountry
FROM Orders 
WHERE CustomerID = @CustomerID
```
Note

Verify the correct parameter syntax for your database. For example, in Microsoft Access, the WHERE clause would look like: WHERE CustomerID = ?.
Click Next.
For the Fill a DataTableMethod Name, type FillByCustomerID.
Clear the Return a DataTable option, and then click Next.
Click Finish.

Creating a Method on Form2 to Pass Data To

To create a method to pass data to

Right-click Form2 and select View Code to open Form2 in the Code Editor.

Add the following code to Form2 after the Form2_Load method:

Friend Sub LoadOrders(ByVal CustomerID As String)
    OrdersTableAdapter.FillByCustomerID(NorthwindDataSet.Orders, CustomerID)
End Sub

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

Creating a Method on Form1 to Pass Data and Display Form2

To create a method to pass data to Form2

In Form1, right-click the Customer data grid, and then click Properties.
In the Properties window, click Events.
Double-click the CellDoubleClick event.

The code editor appears.

Update the method definition to match the following sample:

Private Sub CustomersDataGridView_DoubleClick() Handles CustomersDataGridView.DoubleClick

    Dim SelectedRowView As Data.DataRowView
    Dim SelectedRow As NorthwindDataSet.CustomersRow

    SelectedRowView = CType(CustomersBindingSource.Current, System.Data.DataRowView)
    SelectedRow = CType(SelectedRowView.Row, NorthwindDataSet.CustomersRow)

    Dim OrdersForm As New Form2
    OrdersForm.LoadOrders(SelectedRow.CustomerID)
    OrdersForm.Show()
End Sub

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 the Application

To run the application

Press F5 to run the application.
Double-click a customer record in Form1 to open Form2 with that customer's orders.

Next Steps

Depending on your application requirements, there are several steps you may want to perform after passing data between forms. Some enhancements you could make to this walkthrough include:

Editing the dataset, to add or remove database objects. For more information, see How to: Edit a Dataset.
Adding functionality to save data back to the database. For more information, see How to: Save Dataset Changes to a Database.

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