如何同步Database和DataGridView

Question

I have been trying to synchronize a database trough a DataGridView . So far I have created a data model class. This class contains multiple Properties that match the database. They are mapped using the [Table] and [Column] attributes from the System.Data.Linq.Mapping namespace.

Ok. So I bound the DataGridView using the DataSource -Property to a DataContext connecting to the Database (MSSQL). This Logic is implemented in a singleton class, so I can assure there is a single instance of this DataContext .

 this.m_context = new DataContext(conn);
 this.m_VisitorTable = m_context.GetTable<Visitor>();

Well, if I bind the table to my DataGridView.DataSource I can see all my entries from the database loaded and shown correctly. Then if I change something I found myself confronted with the synchronization problem. The changed cell did not change on the database side.

To save the changes I implemented this method:

public void SaveChanges()
{
    try
    {
       // I have no idea what I'm doing here.
       VisitorLogic.Instance.m_VisitorTable.Context.SubmitChanges(System.Data.Linq.ConflictMode.Con
       // I'm also trying to see if changes were made so I can save them before closing.
       this.m_bChangesMade = false;
    }
    catch (Exception ex)
    {
        MessageBox.Show("Failed to save.", "Error");
    }
 }

Is there a way to make the whole synchronizing to the database happen automatically? Like autocommit on change. I guess I will have to change something on the model Class. Right now, it does not implement any interfaces nor inherit anything.

This is the class declaration:

[Table(Name = "tblVisitor")]
public class Visitor

Further on, I have not found a way to update my DataGridView "correctly". This is how I make it now, but it seems it's not always working. Is there a better way to do this?

// Retrieve the new data from the database
VisitorLogic.Instance.m_VisitorTable.Context.Refresh(System.Data.Linq.RefreshMode.OverwriteCurrentValues, VisitorLogic.Instance.m_VisitorTable);


// Set the DataSource to 'null'
this.dataGridView.DataSource = null;

// Refresh (?!)
this.dataGridView.Refresh();

// Bind the new DataSource, hoping it will show the new data.
this.dataGridView.DataSource = VisitorLogic.Instance.m_VisitorTable;
this.m_bChangesMade = false;

Thanks for your help!

Answer 1

You need to use the BindingSource object. This will keep your DataTable synchronized with the DataGridView.

So set the DataSource of the BindingSource to the table, then set the DataSource of the DataGridView to the BindingSource.

Example:

// DataGridView
DataGridView dg = new DataGridView();

// BindingSource (used for synchronizing table and grid)
BindingSource bs = new BindingSource();

// Set DataSource of BindingSource to table
bs.DataSource = table;

// Set grid DataSource
dg.DataSource = bs;

To update the underlying database you would usually call

bindingsource.EndEdit();
dataAdapter.Update(dataTable);

Here's a tutorial and a bit more in-depth info about the binding source object:

Saving Data from Application to Database (msdn):

Data Binding using LINQ to SQL in C#