如何在 WPF 中刷新/重新加载数据网格？

Question

I want to implement a datagrid, which will be filled every 5min.

But, first code: XAML:

    <Window.Resources>
    <ObjectDataProvider x:Key="_employeeProvider" ObjectType="{x:Type Brw1:EmployeeDataProvider}" />
    <ObjectDataProvider x:Key="_employeeFactory" ObjectInstance="{StaticResource _employeeProvider}" MethodName="GetEmployees" />
</Window.Resources>

<Grid DataContext="{Binding Source={StaticResource _employeeFactory}}">
    <DataGrid Name="_employeeDataGrid" DockPanel.Dock="Top" Margin="12,57,12,0" VerticalAlignment="Top" ItemsSource="{Binding}" AutoGenerateColumns="True">
    </DataGrid>
</Grid>

C#:

    public class EmployeeDataProvider
{
    public ObservableEmployee GetEmployees()
    {
        // This is only example
        // In my project right here I will get data from database, put into the list, and fill datagrid with it. 
        List<UIEmployee> list = new List<UIEmployee>
                {
                    new UIEmployee { Id = 1, FirstName = "Prajeesh2", LastName = "Prathap", Occupation = "Engineer", DateOfJoining=new DateTime(2005, 8, 1), IsContracter = false, AddressInfo = null },
                    new UIEmployee { Id = 2, FirstName = "Rahul2", LastName = "Bose", Occupation = "Student", DateOfJoining=new DateTime(2009, 5, 4), IsContracter = true, AddressInfo = null },
                    new UIEmployee { Id = 3, FirstName = "Steve2", LastName = "Roberts", Occupation = "Manager", DateOfJoining=new DateTime(1994, 8, 23), IsContracter = false, AddressInfo = null },
                    new UIEmployee { Id = 4, FirstName = "Micheal2", LastName = "Clarke", Occupation = "Engineer", DateOfJoining=new DateTime(2003, 1, 14), IsContracter = true, AddressInfo = null },
                    new UIEmployee { Id = 5, FirstName = "Rachel2", LastName = "Green", Occupation = "Professional", DateOfJoining=new DateTime(2006, 3, 8), IsContracter = true, AddressInfo = null }
                };

        ObservableEmployee employeeCollection = new ObservableEmployee(list);
        return employeeCollection;
    }
}

It is very simple. Datagrid use GetEmployees() method to get data.

What I try to do, is to run GetEmployess every 5min..

PS. _employeeDataGrid.Items.Refresh(); - doesn't work.

UPDATE:

Missing classes:

    public class ObservableEmployee : ObservableCollection<UIEmployee>
{
    public ObservableEmployee(IEnumerable<UIEmployee> employees) : base(employees) { }
}

public class UIEmployee// : INotifyPropertyChanged
{
    private int m_Id;
    public int Id
    {
        get { return m_Id; }
        set
        {
            m_Id = value;
        }
    }

    private string m_FirstName;
    public string FirstName
    {
        get { return m_FirstName; }
        set
        {
            m_FirstName = value;
        }
    }

    private string m_LastName;
    public string LastName
    {
        get { return m_LastName; }
        set
        {
            m_LastName = value;
        }
    }

    private string m_Occupation;
    public string Occupation
    {
        get { return m_Occupation; }
        set
        {
            m_Occupation = value;
        }
    }

    private DateTime m_DateOfJoining;
    public DateTime DateOfJoining
    {
        get { return m_DateOfJoining; }
        set
        {
            m_DateOfJoining = value;
        }
    }

    private bool m_IsContracter;
    public bool IsContracter
    {
        get { return m_IsContracter; }
        set
        {
            m_IsContracter = value;
        }
    }

}

UPDATE2: I need something, that will reload datagrid, so datagrid will have to use GetEmployees method again.

UPDATE3:

public class TaskDataProvider
{
    static ObservableEmployee list = new ObservableEmployee();
    static DataRepository dr = new DataRepository();

    public static ObservableEmployee GetEmployees()
    {
        UpdateMyList();
        return list;
    }

    public static void UpdateMyList() 
    {
        ObservableTask newList = new ObservableTask(dr.GetTasks());

        list.Clear();
        foreach (Task t in newList)
        {
            list.Add(t);
        }
    }
}

This at start works. But that, I change sth in database, and click the button which do:

TaskDataProvider.UpdateMyList();

And on break point, it's gets right data (new data) - but, datagrid is not refreshing:/

Answer 1

dataGrid1.Items.refresh();

to update the contents of DataGrid

Answer 2

Or, you could just null ItemsSource out and initialised it again:

dataGridView.ItemsSource = null;
dataGridView.ItemsSource = ItemsSourceObjects;

Answer 3

I gues this cause binding is not aware that you changed collection. I would suggest, or:

• Clear and after populate a collection previously binded to grid with a new data (the same collection, as in GetEmployees() you every time create a new one.

or

• Before assigning new collection try to assign to DataContext null or an empty collection and after actually assign a new one.

or

EDIT

 ObservableEmployee <UIEmployee> list = new ObservableEmployee <UIEmployee>(); //move list to global variables and declare it as ObservableCollection
 public ObservableEmployee GetEmployees()
    {

       //here only return an instance of list
       return list;

    }

//this method call when you want to update data on gri
public void UpdateMyList() {

     //clear list 
     list.Clear();

     //after add all data
     list.Ad(..);
     list(..); 
     .
     .

}

• Use UpdateTarget like provided in folowing example: DataBinding Refresh in WPF