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gridview update (find control)

Posted on 2008-11-03
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Last Modified: 2013-12-17
I have place an edit/update button on my gridview and I am using the following code to pickup any changes upon editting/updating.

Location_Type = ((TextBox)user_records.Rows[e.RowIndex].FindControl("LocationTypetb")).Text;

The problem is  the code does not read the changes made to the content of the gridview, rather it returns the gridview orginal values.

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Question by:Mr_Shaw
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Expert Comment

by:Juan_Barrera
Comment Utility
Hi,
You should place you code in the gridview's RowEditing or RowUpdating event handlers, which have an e parameter of type GridViewEditEventArgs or GridViewUpdateEventArgs, respectively.
Acessing e properties will give you the old and new values.
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Author Comment

by:Mr_Shaw
Comment Utility
at the moment it is located in GridViewUpdate
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Expert Comment

by:moseack
Comment Utility
You seem to be using a valid approach, but remember that if you are doing a data re-bind then you new values are overwritten with the old values.
Make sure you have the if(IsPostback) clause.

if (!IsPostback)

{

  // Do the Databind dance...

}

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Expert Comment

by:Juan_Barrera
Comment Utility
Sorry, but there is no such event handler in a grid view. Can you please recheck?
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Author Comment

by:Mr_Shaw
Comment Utility
ok I have changed my code to this

    protected void edit_record_updating(object sender, GridViewUpdateEventArgs e)
    {

        update_records_method.Record_ID = ((TextBox)user_records.Rows[e.RowIndex].FindControl("RecordIDtb")).Text.ToString();
        update_records_method.Logon_Name = WindowsIdentity.GetCurrent().Name.ToString();
        update_records_method.Record_Class = ((TextBox)user_records.Rows[e.RowIndex].FindControl("RecordClasstb")).Text.ToString();

  if (!Page.IsPostBack)
        {
         BindData();   // Do the Databind dance...
        }

}

Is this correct
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Expert Comment

by:moseack
Comment Utility
Not excatly, what I ment.
You need to do this ONLY If you already have Data Binding in any of the previous Event handlers (Page_Init or Page_Load), similar to:

protected void Page_Load(object sender, EventArgs e)

{

  if (!Page.IsPostBack)

  {

    BindData();   // Do the Databind dance...

  }

}

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Expert Comment

by:Juan_Barrera
Comment Utility
If all these TextBoxes are part of the row you are updating, you should get the new values from the e parameter of the method (the e.NewValues collection). There is no need to find the controls.
Just have a look at what's returned by "e", and you'll see what I mean.
Also, there is no need to call BindData there.
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Author Comment

by:Mr_Shaw
Comment Utility
Ok, what i have done is put

if i use e.NewValues  how do i distinguish between the many textboxes in gridview edit.
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Expert Comment

by:Juan_Barrera
Comment Utility
Have a look at this link, it might be useful: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridviewupdateeventargs.newvalues.aspx
But, in short, you can get them by index or by key, for example, :
update_records_method.Record_ID = e.NewValues(index_of_the_column_containing_the_record_id).ToString
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Author Comment

by:Mr_Shaw
Comment Utility
I used the following code

string test = e.NewValues[3].ToString();

i got the following error.

Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

I also used the approach stated in the link ; foreach (DictionaryEntry.........I put a break point on the foreach loop, but the code just skipped through this section.
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Expert Comment

by:Juan_Barrera
Comment Utility
Mmm..so what's the lenght of the NewValues collection (e.NewValues.Count)?
If it's 0, then there is something wrong with the update logic. How are you dataBinding the grid? If you try your code in the GridViewUpdated event, is the e.NewValue collection empty  as well?
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Author Comment

by:Mr_Shaw
Comment Utility
Ahhhhhhhhhhhhhh e.NewValues.Count was equal to 0.

I am binding the grid using

        user_records.DataSource = users;
        user_records.DataBind();
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Expert Comment

by:Juan_Barrera
Comment Utility
And if you try your code in the GridViewUpdated event, is the e.NewValue collection empty as well?
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Author Comment

by:Mr_Shaw
Comment Utility
i put the code in GridViewUpdated and applied a break point. However, the code did not pass through the GridViewUpdated event.
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Expert Comment

by:Juan_Barrera
Comment Utility
but did you set GridViewUpdated as a handler? , like:
 

<asp:GridView ID="GridView1" runat="server" OnRowUpdated="GridViewUpdated" moreProperties......>

        </asp:GridView>

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Author Comment

by:Mr_Shaw
Comment Utility
I have set all the handlers


        <asp:GridView ID="user_records" runat="server" 

            onprerender="edit_record_PreRender" 

            onrowcancelingedit="edit_record_RowCancelingEdit" 

            onrowdeleted="edit_record_RowDeleted" onrowdeleting="edit_record_RowDeleting" 

            onrowediting="edit_record"  

            onrowupdating="edit_record_updating" 

            OnRowUpdated="edit_record_updated"

            onselectedindexchanged="edit_record_SelectedIndexChanged" 

            onselectedindexchanging="edit_record_SelectedIndexChanging" 

            onsorted="edit_record_Sorted" onsorting="edit_record_Sorting" 

            onrowdatabound="edit_record_RowDataBound">

            <Columns>

                <asp:CommandField ShowEditButton="True" />

                <asp:CommandField ShowDeleteButton="True" />

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Expert Comment

by:Juan_Barrera
Comment Utility
Can you please then post you markup and the code-behind for the edit / update events?
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Author Comment

by:Mr_Shaw
Comment Utility
here is my code
    protected void edit_record(object sender, GridViewEditEventArgs e)

    {
 

        user_records.EditIndex = e.NewEditIndex;

        BindData(); 

        

    }
 
 

    protected void edit_record_updated(object sender, GridViewUpdatedEventArgs e)

    {

        Response.Write(e.NewValues.Count.ToString() + " updated");

     }

    protected void edit_record_updating(object sender, GridViewUpdateEventArgs e)

    {
 

       Response.Write( e.NewValues.Count.ToString() + " update");
 
 

    }

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Expert Comment

by:Juan_Barrera
Comment Utility
But, if that worked, is going to give you the number of cells updated, is that what you want?

I'm now a bit confused about how this relates with the original question. If there is anything you can provide us to clarify, it would be appreciated.
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Author Comment

by:Mr_Shaw
Comment Utility
It does not work. When I update the values in the gridview, the updated values are not picked up by the code.

I have used break point to test my code and the same thing happens every time, the code just does not recognise that I have changed a value.
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Expert Comment

by:Juan_Barrera
Comment Utility
All right, so: How are you binding the grid? I can't see it in the markup you posted. Is it in code behind? Can you please post it?

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Author Comment

by:Mr_Shaw
Comment Utility
in page load i use the following      


      user_records.DataSource = users;
            user_records.DataBind();


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Expert Comment

by:Juan_Barrera
Comment Utility
do you check for post back?

if (!IsPostback)
{
            user_records.DataSource = users;
            user_records.DataBind();
}
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Author Comment

by:Mr_Shaw
Comment Utility
I chanegd my code to read

if (!Page.IsPostBack)
            {
                user_records.DataSource = users;
                user_records.DataBind();
            }

now i can't get rid of the update button.
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Accepted Solution

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Juan_Barrera earned 500 total points
Comment Utility
Sorry, but I mean to say that you should bind the gridview upon every post-back.
As you are not using DataSourceID, you should create code to do this.

I'll leave you to find out how to do this, it's just a matter of going through the MSDN documentation.

Anyway, now you know in what events and in what parameter you'll find you old / new values.
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Author Comment

by:Mr_Shaw
Comment Utility
I am still in the same situtaion as before. I know what events do what.

I don't understand why i need to give a datasourceID
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Author Comment

by:Mr_Shaw
Comment Utility
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Author Closing Comment

by:Mr_Shaw
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