GridView.Databind() not working with object list

Question

The problem I have is this: I have one GridView with a list objects as its data source, it binds with no problem. I have a DropDownList which have the event SelectedIndexChanged, and with this event, I add a new object to the list, after added I want to do a GridView1.Databind() so the new object appears in the GridView.

But this does not work, after I do GridView1.Databind() the data from the GridView gets lost. It even shows the EmptyDataText, but if I refresh the page, everything appears. Also, the DropDownList uses an object list as DataSource and was supposed to use DropDownList1.Databind() but it doesn't work too. It has the same data after the DataBinding, what I did to correct at least the DropDownList was to set the DropDownList again manually.DataTextField = object.attribute1 and DropDownList.DataValueField = object.attribute2. But with the GridView I'm stuck, can someone explain how the method DataBind works with a list of objects?

To the list of objects, and it has no problem, it display all the data correctly the only problem is trying to refresh it — Thiago Ruiz
– Thiago Ruiz, Commented Sep 18, 2012 at 18:06

alexm · Accepted Answer · 2012-09-18 18:17:31Z

1

To refresh a asp:GridView bound to a list set gridView.DataSource property first.

 gridView.DataSource = mylist;
 gridView.DataBind();

For non-database data it means that list itself must be preserved either in session variable or ViewState.

answered Sep 18, 2012 at 18:17

alexm

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3 Comments

Thiago Ruiz Over a year ago

everytime I need to do gridView.Databind() I need to do this? I've did this in the PageLoad() already. Before using this list my system used MySqlDataSource, but now we are using ADO.net for security reasons and with MySqlDataSource you only needed to associate the DataSource of the GridView once. By the way, thanks for the answer with this it works.

alexm Over a year ago

I bet with MySqlDataSource you were using DataSourceID property. Which is, indeed, has to be assigned only once. DataSource, on the other hand is not persistable, each post back sets it back to null

Thiago Ruiz Over a year ago

That's it, thank you for the answer, just created a method called GridView2Databind() wich contain this two lines, since my code to create the object list come from a class e to call it I need to use GridView2.DataSource = emit_bo.GetEmitenteTipo(Convert.ToInt32(GridView1.SelectedValue)); I would be not easy to write all this everytime I need to do a Databind. Note that the code is a little complex because of one gridview depends on the other, didn't posted anything related to it because thought it would get harder to undestand.

Relevant · Accepted Answer · 2012-09-18 18:00:39Z

0

I remember having this issue a long time ago. I'm guessing the issue is that you don't have the GridView in an UpdatePanel.

If this is the case, the GridView won't refresh and show the changes right away. There's some trickiness about the dropdown placement (I think it has to be in the panel, as well), but I'm sure you can figure it out with some quick searches on UpdatePanel.

answered Sep 18, 2012 at 18:00

Relevant

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1 Comment

Thiago Ruiz Over a year ago

Thanks for the recomendation, didn't knew about this update panel, very useful, but didn't fixed it

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