How to update database without using SqlDataSource

[AnagJohari]

If I want to access the method in which we define update query, how can I access that method on aspx page & update the data in a grid view without direct use of an query on aspx page under sql data source?

[Frinavale]

What you would have to do is implement a method that handles the GridView.RowUpd ating Event. In this method you will have to retrieve the data from the row that is updating and use this data to update your database.

I'm not sure what you're stuck on so if you provide more information I can give you more help on the topic.

-Frinny

[AnagJohari]

@Frinavale
sorry frinny for my titile i use......
Actually I made a data acces layer class, buiness logic layer class & presentation layer(.aspx page). Now I want to update the data in a grid view.
In most of the books generally direct update query is written on aspx page under sql data source using update commnad property & do updation in grid view.
Here is the code

<asp:SqlDataSource ID="datasource1" ProviderName="System.Data.SqlClient"  runat="server" ConnectionString="<%$ConnectionStrings:ConnectionString%>" SelectCommand="Select * From ManageClient" 
 UpdateCommand="Update ManageClient Set ClientName=@ClientName,Address=@Address,MobileNo=@MobileNo,Image=@Image Where ClientId=@ClientId"></asp:SqlDataSource>
 

Connect it to the grid view.

Now i do not want to use update command or connection string in sql data source.
This thing I have done in data acces layer class where I make a method of an update.
I want to use this method so I can do an update in grid view directly.

[Frinavale]

I've never actually used the SqlDataSource before. I like to be in more control of my database connections.

Anyways, it's not that hard to do. Delete your SqlDataSource.. .you don't need it. You don't need to use a SqlDataSource at all. GridViews can bind to DataTables, DataViews, Arrays of Objects ...and more.

So, you need to populate the object that you are going to use as your data source at some point in your page life cycle. You could do this in your Page Load event if you want to.

You could cache the object that you are going to use as a data source too. This way you don't have to repopulate the data source every page postback. This saves time but it depends on how long you can tolerate "old data" being displayed.

Anyways, once you've populated your data source (or retrieved it from cache) you set the GridView.DataSo urce property to the object you are using...then call the GridView.DataBi nd method to bind the GridView to the data source. I do this in the Page PreRender event for a bunch of reasons....for example if you bind in the Page Load event every page request you will have problems with getting the values that the user entered while editing (because these values will be over written with the data that you've bound to).

In your GridViews OnRowUpdating event you will call your data access layer's methods to do the updating....

That's pretty much it.

-Frinny

[AnagJohari]

@Frinavale
You said that we have to bind object with grid view at page.prerender . I think if we do the same thing on page load event it work because value is set when row updating event is fired. When this event fired it saves the values at their view state & this view state is sent to the client. That is the concept of page life cycle. Am I right?

[Frinavale]

Not quite right.
What happens is that the ViewState for the GridView is loaded just before the Page Load event. This means that all of the data that the user provided for the row that they are updating is loaded into the ASP.NET controls used to access the data in your C#/VB.NET code.

If you do a DataBind in the Page Load event then all of this data is lost!
Edit: if you do a DataBind in the Page Load event every page request all of your data will be lost

It's the most common problem that people have with GridViews that I've noticed.

If you don't need to get data from the user, than yes you can do the DataBind in the Page Load event. But if you need to get data from the user for updating purposes then, no, you should do it in the Page PreRender event instead.

-Frinny

[AnagJohari]

@Frinavale
The event is fired between load view state & save view state when the event is fired it set the values in textbox or whatever server control we used. After that it saves the values in view state. Then there is no matter of data loss if you load the page again but I have to bind data in a grid view through view state on page load no chance of data loss.

[Frinavale]

You are mistaken.

Events are created when the ViewState is loaded. Methods that handle events occur after the Page Load event.

This is the basic outline of what happens in the ASP.NET Life Cycle:

• Page Init (before ViewState is loaded)
• Page Load (after ViewState is loaded)
• Event handling code is executed
• Page PreRender (occurs Just before the page is rendered as HTML)

Please review the ASP.NET Page Life Cycle for a more detailed explination.

If you perform a GridView.DataBi nd in the Page Load event (without checking if it's postback) then you will not be able to retrieve user input in the GridView.RowEdi ting event.

-Frinny

[AnagJohari]

@Frinavale
Can you tell me when the data is saved in a view state & that data is loss from the view state next time when it load the view state?

[Frinavale]

The ViewState is stored some time in between the Page PreRender event and the SaveStateComple te event (heading towards the Render stage).

All of this is covered in the article I sent you a link to :)

I'm not sure what you mean by:

AnagJohari: that data is loss from the view state

Maybe you're talking about data loss that happens if you don't call the DataBind method??