[WPF]DataGrid のセルに存在するコントロールを取得する

gistfile1.cs

using System.Windows.Controls.Primitives;

this.dataGrid.Items.ForEach<DataGridRowViewModel>(viewModel =>
{
    var dataGridRow = this.dataGrid.ItemContainerGenerator.ContainerFromItem(viewModel) as DataGridRow;
    var cellsPresenter = dataGridRow.FindVisualChild<DataGridCellsPresenter>();
    var cell = cellsPresenter.ItemContainerGenerator.ContainerFromItem(viewModel) as DataGridCell;
    var presenter = cell.Content as ContentPresenter;
    var dbOutputValueTextBox = presenter.ContentTemplate.FindName("valueTextBox", presenter) as TextBox;
    viewModel.Value = valueTextBox.Text;
});