Como compartilhar dados associados entre formulários usando o componente BindingSource

Você pode facilmente compartilhar dados entre formulários usando o BindingSource componente. Por exemplo, talvez você queira exibir um formulário de somente leitura que resume os dados de origem de dados e outro formulário editável que contém informações detalhadas sobre o item atualmente selecionado na fonte de dados. Este exemplo demonstra esse cenário.

Exemplo

O exemplo de código a seguir demonstra como compartilhar um BindingSource e seus dados vinculados entre formulários. Neste exemplo, o compartilhado BindingSource é passado para o construtor do formulário filho. O formulário filho permite que o usuário edite os dados para o atualmente item selecionado no formulário principal.

Observação

O BindingComplete evento para o BindingSource componente é manipulado no exemplo para garantir que os dois formulários permaneçam sincronizados. Para obter mais informações sobre o motivo de isso ser feito, consulte Como assegurar que vários controles associados à mesma fonte de dados permaneçam sincronizados.

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Data;

namespace BindingSourceMultipleForms
{
    public class MainForm : Form
    {
        public MainForm()
        {
            this.Load += new EventHandler(MainForm_Load);
        }

        private BindingSource bindingSource1;
        private Button button1;

        private void MainForm_Load(object sender, EventArgs e)
        {
            InitializeData();
        }

        private void InitializeData()
        {
            bindingSource1 = new System.Windows.Forms.BindingSource();

            // Handle the BindingComplete event to ensure the two forms
            // remain synchronized.
            bindingSource1.BindingComplete +=
                new BindingCompleteEventHandler(bindingSource1_BindingComplete);
            ClientSize = new System.Drawing.Size(292, 266);
            DataSet dataset1 = new DataSet();

            // Some xml data to populate the DataSet with.
            string musicXml =
                "<?xml version='1.0' encoding='UTF-8'?>" +
                "<music>" +
                 "<recording><artist>Dave Matthews</artist>" +
                 "<cd>Under the Table and Dreaming</cd>" +
                 "<releaseDate>1994</releaseDate><rating>3.5</rating></recording>" +
                 "<recording><artist>Coldplay</artist><cd>X&amp;Y</cd>" +
                 "<releaseDate>2005</releaseDate><rating>4</rating></recording>" +
                 "<recording><artist>Dave Matthews</artist>" +
                 "<cd>Live at Red Rocks</cd>" +
                 "<releaseDate>1997</releaseDate><rating>4</rating></recording>" +
                 "<recording><artist>U2</artist>" +
                 "<cd>Joshua Tree</cd><releaseDate>1987</releaseDate>" +
                 "<rating>5</rating></recording>" +
                 "<recording><artist>U2</artist>" +
                 "<cd>How to Dismantle an Atomic Bomb</cd>" +
                 "<releaseDate>2004</releaseDate><rating>4.5</rating></recording>" +
                 "<recording><artist>Natalie Merchant</artist>" +
                 "<cd>Tigerlily</cd><releaseDate>1995</releaseDate>" +
                 "<rating>3.5</rating></recording>" +
                 "</music>";

            // Read the xml.
            System.IO.StringReader reader = new System.IO.StringReader(musicXml);
            dataset1.ReadXml(reader);

            // Get a DataView of the table contained in the dataset.
            DataTableCollection tables = dataset1.Tables;
            DataView view1 = new DataView(tables[0]);

            // Create a DataGridView control and add it to the form.
            DataGridView datagridview1 = new DataGridView();
            datagridview1.ReadOnly = true;
            datagridview1.AutoGenerateColumns = true;
            datagridview1.Width = 300;
            this.Controls.Add(datagridview1);
            bindingSource1.DataSource = view1;
            datagridview1.DataSource = bindingSource1;
            datagridview1.Columns.Remove("artist");
            datagridview1.Columns.Remove("releaseDate");

            // Create and add a button to the form.
            button1 = new Button();
            button1.AutoSize = true;
            button1.Text = "Show/Edit Details";
            this.Controls.Add(button1);
            button1.Location = new Point(50, 200);
            button1.Click += new EventHandler(button1_Click);
        }

        // Handle the BindingComplete event to ensure the two forms
        // remain synchronized.
        private void bindingSource1_BindingComplete(object sender, BindingCompleteEventArgs e)
        {
            if (e.BindingCompleteContext == BindingCompleteContext.DataSourceUpdate
                && e.Exception == null)
                e.Binding.BindingManagerBase.EndCurrentEdit();
        }

        // The detailed form will be shown when the button is clicked.
        private void button1_Click(object sender, EventArgs e)
        {
            DetailForm detailForm = new DetailForm(bindingSource1);
            detailForm.Show();
        }

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.Run(new MainForm());
        }
    }

    // The detail form class.
    public class DetailForm : Form
    {
        private BindingSource formDataSource;

        // The constructor takes a BindingSource object.
        public DetailForm(BindingSource dataSource)
        {
            formDataSource = dataSource;
            this.ClientSize = new Size(240, 200);
            TextBox textBox1 = new TextBox();
            this.Text = "Selection Details";
            textBox1.Width = 220;
            TextBox textBox2 = new TextBox();
            TextBox textBox3 = new TextBox();
            TextBox textBox4 = new TextBox();
            textBox4.Width = 30;
            textBox3.Width = 50;

            // Associate each text box with a column from the data source.
            textBox1.DataBindings.Add("Text", formDataSource, "cd", true, DataSourceUpdateMode.OnPropertyChanged);

            textBox2.DataBindings.Add("Text", formDataSource, "artist", true);
            textBox3.DataBindings.Add("Text", formDataSource, "releaseDate", true);
            textBox4.DataBindings.Add("Text", formDataSource, "rating", true);
            textBox1.Location = new Point(10, 10);
            textBox2.Location = new Point(10, 40);
            textBox3.Location = new Point(10, 80);
            textBox4.Location = new Point(10, 120);
            this.Controls.AddRange(new Control[] { textBox1, textBox2, textBox3, textBox4 });
        }
    }
}

Imports System.Drawing
Imports System.Windows.Forms
Imports System.Data

Public Class MainForm
    Inherits Form

    Public Sub New()
    End Sub

    Private WithEvents bindingSource1 As BindingSource
    Private WithEvents button1 As Button

    Private Sub MainForm_Load(ByVal sender As Object, ByVal e As EventArgs) _
        Handles Me.Load

        InitializeData()
    End Sub


    Private Sub InitializeData()
        bindingSource1 = New System.Windows.Forms.BindingSource()
        Dim dataset1 As New DataSet()
        ClientSize = New System.Drawing.Size(292, 266)

        ' Some xml data to populate the DataSet with.
        ' Some xml data to populate the DataSet with.
        Dim musicXml As String = "<?xml version='1.0' encoding='UTF-8'?>" & _
            "<music><recording><artist>Dave Matthews</artist>" & _
            "<cd>Under the Table and Dreaming</cd>" & _
            "<releaseDate>1994</releaseDate><rating>3.5</rating></recording>" & _
            "<recording><artist>Coldplay</artist><cd>X&amp;Y</cd>" & _
            "<releaseDate>2005</releaseDate><rating>4</rating></recording>" & _
            "<recording><artist>Dave Matthews</artist>" & _
            "<cd>Live at Red Rocks</cd>" & _
            "<releaseDate>1997</releaseDate><rating>4</rating></recording>" & _
            "<recording><artist>U2</artist>" & _
            "<cd>Joshua Tree</cd><releaseDate>1987</releaseDate>" & _
            "<rating>5</rating></recording>" & _
            "<recording><artist>U2</artist>" & _
            "<cd>How to Dismantle an Atomic Bomb</cd>" & _
            "<releaseDate>2004</releaseDate><rating>4.5</rating></recording>" & _
            "<recording><artist>Natalie Merchant</artist>" & _
            "<cd>Tigerlily</cd><releaseDate>1995</releaseDate>" & _
            "<rating>3.5</rating></recording>" & _
            "</music>"

        ' Read the xml.
        Dim reader As New System.IO.StringReader(musicXml)
        dataset1.ReadXml(reader)

        ' Get a DataView of the table contained in the dataset.
        Dim tables As DataTableCollection = dataset1.Tables
        Dim view1 As New DataView(tables(0))

        ' Create a DataGridView control and add it to the form.
        Dim datagridview1 As New DataGridView()
        datagridview1.ReadOnly = True
        datagridview1.AutoGenerateColumns = True
        datagridview1.Width = 300
        Me.Controls.Add(datagridview1)
        bindingSource1.DataSource = view1
        datagridview1.DataSource = bindingSource1
        datagridview1.Columns.Remove("artist")
        datagridview1.Columns.Remove("releaseDate")

        ' Create and add a button to the form. 
        button1 = New Button()
        button1.AutoSize = True
        button1.Text = "Show/Edit Details"
        Me.Controls.Add(button1)
        button1.Location = New Point(50, 200)

    End Sub

    ' Handle the BindingComplete event to ensure the two forms
    ' remain synchronized.
    Private Sub bindingSource1_BindingComplete(ByVal sender As Object, _
        ByVal e As BindingCompleteEventArgs) Handles bindingSource1.BindingComplete
        If e.BindingCompleteContext = BindingCompleteContext.DataSourceUpdate _
            AndAlso e.Exception Is Nothing Then
            e.Binding.BindingManagerBase.EndCurrentEdit()
        End If

    End Sub

    ' The detailed form will be shown when the button is clicked.
    Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) _
        Handles button1.Click

        Dim detailForm As New DetailForm(bindingSource1)
        detailForm.Show()
    End Sub


    <STAThread()> _
    Shared Sub Main()
        Application.EnableVisualStyles()
        Application.Run(New MainForm())

    End Sub
End Class

' The detail form class. 
Public Class DetailForm
    Inherits Form
    Private formDataSource As BindingSource

    ' The constructor takes a BindingSource object.
    Public Sub New(ByVal dataSource As BindingSource)
        formDataSource = dataSource
        Me.ClientSize = New Size(240, 200)
        Dim textBox1 As New TextBox()
        Me.Text = "Selection Details"
        textBox1.Width = 220
        Dim textBox2 As New TextBox()
        Dim textBox3 As New TextBox()
        Dim textBox4 As New TextBox()
        textBox4.Width = 30
        textBox3.Width = 50

        ' Associate each text box with a column from the data source.
        textBox1.DataBindings.Add("Text", formDataSource, "cd", _
            True, DataSourceUpdateMode.OnPropertyChanged)

        textBox2.DataBindings.Add("Text", formDataSource, "artist", True)
        textBox3.DataBindings.Add("Text", formDataSource, "releaseDate", True)
        textBox4.DataBindings.Add("Text", formDataSource, "rating", True)
        textBox1.Location = New Point(10, 10)
        textBox2.Location = New Point(10, 40)
        textBox3.Location = New Point(10, 80)
        textBox4.Location = New Point(10, 120)
        Me.Controls.AddRange(New Control() {textBox1, textBox2, textBox3, _
            textBox4})

    End Sub
End Class

Compilando o código

Este exemplo requer:

• Referências aos assemblies System, System.Windows.Forms, System.Drawing, System.Data e System.Xml.

Confira também

• Componente BindingSource
• Vinculação de dados dos Windows Forms
• Como identificar erros e exceções que ocorram na associação de dados