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gridview click event that uses object data

I have a class (let's call it Object) that contains an ID and some other data. I want to display the IDs in a gridview. When the user clicks on an ID in the gridview table, I want the ability to add code that accesses the object of the ID and display the Object's details (it's ID and other stored data).
So far I've been able to store the data in a tabletable and set it as the gridview source, but I haven't been able to extend the click event feature.
Any ideas on how to implement this in C#?

The object used to load into the GridView is gone as soon as the page unloads. The contents are retained in viewstate, but the object is not there. What you need to do is query the data again using the selected ID. Or link the Grid to a DetailsView, which will query the data, as #Wahtever suggested in the comments.

Update a data row inside an asp.net Data Grid View

I think it would be easier for you to understand my problem if I explain the scenario a bit.
What I am doing is developing a system to a doctor using asp.net c#. For the creation of the prescription, I add a check box list for the list of medicines and submit button below it. When the submit button clicked selected check box list items added to the sql server database and show a data grid with the selected medicines in the same page.
In the data grid there are two columns for medicine name and dosage.Medicine name is taken from the database.I need to give the user the ability to enter the dosage through that grid view. I need to use update command because the record is already there in the sql server.But empty value in the dosage column.I tried to use update command in the data source control. But I can't figure out how to give the WHERE clause because I can't specify the database row which the updating record relate to.
I would be glad to hear some help from you. All the comments are welcome.

You need to set a parameter(s), please check this example to understand how it works. I guess, that you've added in the database some column that is unique identifier.. some autoincrement int or guid.

dropdownlist selectedvalue

I've used a webservice to create a dropdownlist of countries and I'm trying to add the dropdownlist selection to the sql database, but when I do that by using ddlCountry.SelectedValue in my insert statement, only the first value in the dropdownlist is showing up in the table. Should I use onselectedindexchanged to somehow store the value? What code should I be using?

Try using ddlCountry.SelectedItem.Value instead.

You need to make sure you're not repopulating your dropdown from the web service on a postback. That will cancel out your selection.

If you are firing some sort of save function on button click's even then you can go ahead with ddl.SelectedItem.Text (if you wan't to store the text in your table) if you want to store the value part of the country list then go ahead with ddl.SelectedItem.Value
SelectedIndexChanged should be only used if you want to perform some action at the time when user selects an item in the drop down

Editable GridView Distinct Drop Down LIsts

I have a simple app I am messing around with its a basic Master/Details layout.
The details panel is actually a tab panel and on one of the tab panels it has a GridView. Within that grid view it shows the "current" in database information with all cells as read only.
alt text http://lh4.ggpht.com/_JU1W2P96pD4/TAeonNNYXgI/AAAAAAAAAq0/Y_-Kse7VObE/ExampleA.jpg
I then have an add button that inserts a row into the GriView and allows the user to enter some information. The first item in my GridView is a DropDownList, which is populated from an ObjectDataSource. This drop down is basically my unique index and there can only be one selected value per GridView.
alt text http://lh3.ggpht.com/_JU1W2P96pD4/TAeonIF3DdI/AAAAAAAAAq4/JhfOTsHgsf8/ExampleWithDropDown.png
What is the best way to remove the values from the list that are already in the GridView? Do I just need to remove the data source and add a OnDataBinding method that iterates through the grid view and generates a valid list of values?
I can't use a service method because if the user adds two rows they would have the option to insert duplicates description types.
Just want to make sure there is not a better way to do this.

Keep the object datasource, which I am assuming is an IEnumerable object, in a Session variable. When someone selects a certain value remove that value from the list in the session variable. Whenever they activate the form where the drop down list is displayed simply rebind the control to the list in the session variable. It will be easier than looping through the grid every time the user adds an entry.

Adding rows to a table based on user input (ASP.NEt)

I have a TextBox entry field where the user will enter a integer value. And then there is a "Create" button, which when clicked upon must generate a Table with 2 columns :
"Name" and "Email" being the column headers.
I want each row to have a textbox in each of these columns.
All of this has to happen after the button is clicked. I have discovered that if you dynamically add a control in ASP.NET(I am using C#) then the controls are lost during postback. And I don't know how to prevent that from happening.
Can somebody please give me some ideas regarding how to go about adding rows dynamically to a table (I tried using the asp.net Server side table control but ran into the "lost-during-postback" problem - can I try with something else like a gridview ? but afaik a GV will not work without data bound to it )
Point to note is that my table has textboxes for user entry and it is not for showing data ..rather it is for accepting data from the user which will be later used to persist details to the database.

Dynamic Controls
That's involved. Here's an interesting article on the issue of dynamic controls.
I think normally if you create dynamic controls then you're responsible for recreating them on postback; however the article contains a way to use the Init event if it's copacetic with your app.
Edit:
or Regular ASP.NET Controls
You can use data bound ASP.NET controls like: DataList, Repeater, GridView, etc. (You can put text boxes and all other kinds of controls into them for repeating in each row - or "item") and bind values to it. If you need to perform some processing on the user input first, then generate an internal Array, List, Dictionary, DataTable etc. (your choice) and bind that data as a data source to the ASP.NET control of choice.
aspnetControl.DataSource = myDataTable;
aspnetControl.DataBind();
or
aspnetControl.DataSourceId = "name_of_control";
There are various ways to assign a data source.
This way you won't run into the same problems as with dynamic control creation; however there is a lot to learn to facilitate this way too.