Do need to databind in gridview? - vb.net

Question

If dt_grid.Rows.Count > 0 Then
dt_grid.DataSource = dt_grid
Else
MessageBox.Show("Not Found Data")
End If
I know that if get datatable in gridview.datasource,ever write gridview.Databind.But I found coding of my friend. He write only get datatable in gridview.datasource but no write gridview.dataBind. Therefore, his coding is not error. Why? Don't need to dataBind?

Answer 1

Are you sure your friend is not using the DataSourceID property?
Here is the difference from MSDN:
When the DataSourceID property is set (instead of the DataSource property), the data-bound control automatically binds to the data source control at run time.
Please take a look at this article and this one.
Hope it helped.
I took the time to do a small example to demonstrate that you need to call DataBind() on a normal asp.net gridview in order to render its data.
If your friend is not calling this, I am guessing that he is binding the grid to a data source in the .aspx code (to a SQLDatasource, on even an ObjectDataSource) and he is modifying that datasource in the code.
Please take a look at the following example:
The default.aspx page:
<%# Page Title="Home Page" Language="C#" AutoEventWireup="true"
CodeBehind="Default.aspx.cs" Inherits="GridViewDemo._Default" %>
<form id="form1" runat="server">
<asp:gridview id="GridView1" runat="server">
<Columns>
<asp:BoundField DataField="ID" />
<asp:BoundField DataField="Name" />
</Columns>
</asp:gridview>
</form>
The codebehind for the page: (it is in C# but I think it is relevant to VB as well)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace GridViewDemo
{
public partial class _Default : System.Web.UI.Page
{
public class Entity
{
public int ID { get; set; }
public string Name { get; set; }
}
protected void Page_Load(object sender, EventArgs e)
{
List<Entity> source = new List<Entity>() { new Entity() { ID = 1, Name = "First" }, new Entity() { ID = 2, Name = "Second" } };
GridView1.DataSource = source;
GridView1.DataBind();
// if you comment this line and run, the gridview is not rendered
}
}
}
Let me know if this answered your question.