Basic C/R/U/D example with Entity Framework?

[Paul]

I'm trying to implement a basic CRUD form using the GridView. I am using EF to populate the grid. I need to set some default values and found this link which shows using the DefaultValuesNeeded event. When I attempt to use this I get a NullReferenceException. 

I'm obviously missing something here, but I'm not sure what.

Are there any examples that show:

• Binding to records retrieved from EF
• Setting default values when adding new records
• Where to hook in saving changes when a record is added/updated/deleted 
• Displaying validation errors

Here's my currently working code for viewing the records:

var context = new FlockWatchEntities();
var forecast = context.ForecastMSTs.Where(i => i.Type == "F").OrderBy(i => i.chrDesc);
grdForecast.DataSource = forecast;

And this is what the code in the DefaultValuesNeeded event looks like:

private void grdForecast_DefaultValuesNeeded(object sender, Telerik.WinControls.UI.GridViewRowEventArgs e)
{
       e.Row.Cells["dtmEntered"].Value = DateTime.Now;
       e.Row.Cells["chrEnteredBy"].Value = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
}

[Julian Benkov]

Hi Paul,

You can use the user events of RadGridView control to implement this functionality. Currently, we not have an example in the context of EF. Here is a sample example of RadGridView implementing autosave functionality using these events:

using System;
using System.Data;
using System.Windows.Forms;
using System.Collections.Generic;
using System.ComponentModel;

namespace Lab
{
    public partial class AutoSavingDataForm : Form
    {
        private List<DataRowView> lastRemovedRows = new List<DataRowView>();

        public AutoSavingDataForm()
        {
            InitializeComponent();

            this.radGridView1.UserAddedRow += new Telerik.WinControls.UI.GridViewRowEventHandler(radGridView1_UserAddedRow);
            this.radGridView1.UserDeletingRow += new Telerik.WinControls.UI.GridViewRowCancelEventHandler(radGridView1_UserDeletingRow);
            this.radGridView1.UserDeletedRow += new Telerik.WinControls.UI.GridViewRowEventHandler(radGridView1_UserDeletedRow);
            this.radGridView1.CurrentRowChanged += new Telerik.WinControls.UI.CurrentRowChangedEventHandler(radGridView1_CurrentRowChanged);
            this.radGridView1.CellValueChanged += new Telerik.WinControls.UI.GridViewCellEventHandler(radGridView1_CellValueChanged);
            this.radGridView1.CellValidating += new Telerik.WinControls.UI.CellValidatingEventHandler(radGridView1_CellValidating);

            this.radGridView1.RowsChanged += new Telerik.WinControls.UI.GridViewCollectionChangedEventHandler(radGridView1_RowsChanged);
        }

        void radGridView1_CellValidating(object sender, Telerik.WinControls.UI.CellValidatingEventArgs e)
        {

        }

        private void Form18_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'adventureWorksDataSet.Contact' table. You can move, or remove it, as needed.
            this.contactTableAdapter.FillBy(this.adventureWorksDataSet.Contact, null);
        }

        void radGridView1_RowsChanged(object sender, Telerik.WinControls.UI.GridViewCollectionChangedEventArgs e)
        {
            if (e.Action == Telerik.WinControls.Data.NotifyCollectionChangedAction.Add)
            {
                //your logic here...
            }
        }

        void radGridView1_CellValueChanged(object sender, Telerik.WinControls.UI.GridViewCellEventArgs e)
        {
            IEditableObject editbaleObject = e.Row.DataBoundItem as IEditableObject;
            if (editbaleObject != null)
            {
                editbaleObject.EndEdit();
            }

            //update data
            DataRowView dataRowView = e.Row.DataBoundItem as DataRowView;
            if (dataRowView != null)
            {
                this.contactTableAdapter.Update(dataRowView.Row);
            }
        }

        void radGridView1_UserDeletingRow(object sender, Telerik.WinControls.UI.GridViewRowCancelEventArgs e)
        {
            for (int i = 0; i < e.Rows.Length; i++)
            {
                DataRowView dataRowView = e.Rows[i].DataBoundItem as DataRowView;
                if (dataRowView != null)
                {
                    this.lastRemovedRows.Add(dataRowView);
                }
            }
        }

        void radGridView1_CurrentRowChanged(object sender, Telerik.WinControls.UI.CurrentRowChangedEventArgs e)
        {
            if (e.OldRow == null)
            {
                return;
            }

            DataRowView dataRowView = e.OldRow.DataBoundItem as DataRowView;
            if (dataRowView != null)
            {
                DataRow dataRow = dataRowView.Row;
                if ( dataRow.RowState == DataRowState.Modified)
                {
                    this.contactTableAdapter.Update(dataRow);
                }
            }
        }

        void radGridView1_UserDeletedRow(object sender, Telerik.WinControls.UI.GridViewRowEventArgs e)
        {
            DataRow[] rows = new DataRow[this.lastRemovedRows.Count];

            for (int i = 0; i < this.lastRemovedRows.Count; i++)
            {
                rows[i] = this.lastRemovedRows[i].Row;
            }

            this.contactTableAdapter.Update(rows);
            this.lastRemovedRows.Clear();
        }

        void radGridView1_UserAddedRow(object sender, Telerik.WinControls.UI.GridViewRowEventArgs e)
        {
            DataRow[] rows = new DataRow[e.Rows.Length];
            for (int i = 0; i < e.Rows.Length; i++)
            {
                DataRowView dataRowView = e.Rows[i].DataBoundItem as DataRowView;
                if (dataRowView != null)
                {
                    rows[i] = this.lastRemovedRows[i].Row;
                }
            }

            this.contactTableAdapter.Update(rows);
        }

    }
}

I hope this helps. Regards,
Julian Benkov
the Telerik team

[Bob]

This is exactly what I am looking for...except in EF.

Any chance somene can provide an example on performing these CRUD Operations using EF?
Thanks
Bob

[Julian Benkov]

Hello Bob,

Please view the answer in your previous forum post.

Regards,
Julian Benkov
the Telerik team

[Peter]

The link in the last reply is broken: "Please view the answer in your previous forum post."

Can I also please have some Entity Framework CRUD examples using Telerik Controls? I don't want to use the auto-binding directly to the EDMX, I want to have a layered architecture.

[Julian Benkov]

Hi Peter,

You can use the Local property of your DbContext EntityFramework object to support this functionality. Please review the attached example for details. Soon our documentation will be updated with an article regarding this subject.

Thank you for your time and cooperation.

Regards,
Julian Benkov
the Telerik team