We Keep Coding

Value of HiddenField Duplicated when called from Nested Gridvew Row Editing

Problem: I'm trying to get a value from a HiddenField object and set it to a string. A value of "foo" is being returned as "foo, foo".
Details:
I have a Nested Gridview, and I'm trying to make the child Gridview editable. I have a method GetChildQuery(string id) which form the sql query to get the data for the Child Gridview, and I have the id bound to a HiddenField object in the HTML as so:
<asp:Gridview ID="gvChild" runat="server" AutoGenerateColumns="false" OnRowEditing = "gvChild_RowEditing">
<Columns>
<asp:TemplateField HeaderText="Name">
<ItemTemplate>
<asp:Label runat="server" ID="lblNameChild" Text='<% Eval("Name")%>'></asp:Label>
<asp:HiddenField runat="server" ID="hidIDChild" Value ='<%# Bind("ItemID") %>' />
</ItemTemplate>
<EditItemTemplate>
<asp:Label runat="server" ID="lblNameChildEdit" Text='<% Eval("Name")%>'></asp:Label>
<asp:HiddenField runat="server" ID="hidIDChildEdit" Value ='<%# Bind("ItemID") %>' />
</EditItemTemplate>
</asp:TemplateField>
and I try to access it in the OnRowEditing method like:
protected void gvhild_RowEditing(object sender, GridViewEditEventArgs e) {
Gridview child = sender as Gridview;
string itemID = (child.Rows[e.NewEditIndex].FindControl("hidIDChild") as HiddenField).Value.ToString();
string sql = GetChildQuery(itemID);
child.EditIndex = e.NewEditIndex;
child.DataSource = GetData(sql);
child.DataBind();
}
The id is used in the WHERE clause of my SQL query, and therefore the output is incorrect if the value of the id is incorrect. I don't know I this problem is occurring because of how I bind data to the HiddenField or how I'm calling it from the RowEditing method, or something I'm completely overlooking.
Ref: To make the Nested Gridview, I mainly followed https://www.aspsnippets.com/Articles/Nested-GridView-Example-in-ASPNet-using-C-and-VBNet.aspx and https://www.aspforums.net/Threads/133072/Edit-Update-Delete-in-Nested-Child-GridView-in-ASPNet/ which has the general format for my GetData method as well.
EDIT: Problem subverted by replacing the string itemID instantiation to
string itemID= ((child.Rows[e.NewEditIndex].FindControl("hidIDChild") as HiddenField).Value.Split(','))[0].ToString();
essentially splitting the duplication, accessing the first element, converting that to a string, and setting that equal to y string itemID.
However while this subverts the problem, I would still appreciate anyone's feedback as to why the problem is occurring in the first place. Thanks!

You should look at your rendered html.
When dealing with one gridview there is only ever one row open for editing at a time. And within a row's TemplateField the ItemTemplate and EditTemplate are mutually exclusive, that is to say that, when rendered, you will see only one or the other.
Likewise in the code behind, you will only have access to either the ItemTemplate row or the EditTemplate row depending on which event you process on postback.
The same rules apply to a nested/child Gridview.
So for the case you describe, I assume you are trying to use some ID from the parent to build a query to populate the child. If so I do not believe you need any hidden fields at all. This ID fieldname from the parents query should be set in the DataKeyNames property of the parent gridview.
You should then be able to pass the value to the procedure you are building for the child as
protected void gvhild_RowEditing(object sender, GridViewEditEventArgs e) {
string sql = GetChildQuery(gvParent.SelectedDataKey.Value);
child.DataSource = GetData(sql);
child.DataBind();
// Given that you have just populated the child I do not think the
// following is accurate, but that's for you to decide
child.SetEditRow(e.NewEditIndex);
}
Hope this helps.

Loading Gridview

I have a gridview that is populated from the code behind, and has about 300 rows. When I try to access the page containing it, everything loads, and then about 5 seconds later, the program quits and this error message appears:
If I press continue, the application stops running. However, when I look at the page, all of the data has loaded into the gridview (but of course my links, etc, don't work because the session has stopped running).
If I put less data in the table that populates the gridview, I do not get an error (it works with about 30 rows--I'm not sure the exact point where it becomes too much data). Anyway, since it is the exact same code but just less data, I know that I don't actually have an infinite loop or infinite recursion like the message suggests.
Here is the html for the gridview:
<div id="dvGrid" class="gridTable">
<asp:GridView runat="server" ID="GridView1" OnRowDataBound="GridView1_RowDataBound">
<Columns>
<asp:BoundField DataField="Edit" HtmlEncode="false" HeaderText="" HeaderStyle-Wrap="false" SortExpression="Edit" />
</Columns>
</asp:GridView>
</div>
Here is where it is populated in the code behind (this is in the Page_Load method):
DataTable dt = OpenWeather10Day.DBQueries.GetHistoricalData(_Zip);
dt.Columns["Date"].SetOrdinal(0);
GridView1.DataSource = dt;
_LinkColIndex = dt.Columns["Edit"].Ordinal;
_CommentsColIndex = dt.Columns["Comments"].Ordinal;
GridView1.DataSource = dt.DefaultView;
GridView1.DataBind();
And here is the OnRowDataBound function:
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{//remove double edit column and add a div in comments column to make it the correct size
TableCell cell = e.Row.Cells[0];
e.Row.Cells.RemoveAt(0);
e.Row.Cells.RemoveAt(_LinkColIndex);
e.Row.Cells.Add(cell);
if (e.Row.RowType == DataControlRowType.DataRow) {
TableCell commentsCell = e.Row.Cells[_CommentsColIndex];
HtmlGenericControl div = new HtmlGenericControl("DIV");
div.Attributes.Add("class", "innerDiv");
div.InnerHtml = commentsCell.Text;
commentsCell.Text = string.Empty;
commentsCell.Controls.Add(div);
}
}
I have discovered that the error is with my "edit" column. If I delete the edit column from the table and get rid of all of the code related to it, all 300 rows load with no problem and the page is still active. The problem is that the edit column is critical to my page, so that is not a possible solution.
I've looked into pagination on scroll, but I can't find an example/demo that does exactly what I need or is simple enough for me to follow (I'm pretty much a complete beginner). I also don't think that it should be necessary to implement pagination; it's okay if the page takes a few seconds to load. My real problem/question is with the stack overflow that causes the session to quit. I have no idea what it is about the edit column that is causing this to occur, but somehow I need to fix this so that accessing this page doesn't quit the entire session. I am willing to add pagination on scroll if it is the only option, but like I said, I haven't been able to figure it out yet. I'm also not sure that it would fix the problem. I'm happy to post any other code, etc, if it'd be at all helpful!

Can you explain what is in your Edit column? Is it a Url, preformatted HTML? What will it do?
You are seeing 2 Edit columns because you have one added in your GridView, then you are adding a second one when you bind your data. Use the AutoGenerateColumns property to prevent this, then add in your other columns.
Example
<asp:GridView runat="server" ID="GridView1"
AutoGenerateColumns="false">
<Columns>
<asp:BoundField DataField="Edit" HeaderText="Edit" />
<asp:BoundField DataField="Date" HeaderText="Date" />
<asp:TemplateField HeaderText="Comments">
<ItemTemplate>
<div class="innerDiv">
<%# Eval("Comments") %>
</div>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
You can use a TemplateField to put in the HTML in to your Comments column and get rid of
OnRowDataBound="GridView1_RowDataBound"

Show images in GridView (loaded from URLs stored in SQL database)

I'm very new to ASP.NET and C# and I would need a help here.
My task:
I would like to show images in Grid View from particular URLS. I'm keeping those URLs in my SQL database, but they are NOT complete. What I mean by this:
URL in my database looks like this: "somefolder/imagename.jpg" (without quotes). I would like to concatinate URL from database with my starting url, for example: "www.mypage.com/somefolder/imagename.jpg" and everything show in GridView.
How to start with this particular task? Any help really appriciated.

You can use the ImageField and use the format string attribute to format how the url is formed in relation to the value in the database. The {0} is placeholder for the value coming from the database and will be substituted when the gridview is generated
<asp:GridView runat="server" ID="xxx" AutoGenerateColumns="false">
<Columns>
<asp:ImageField DataImageUrlFormatString="http://mysite/{0}" DataImageUrlField="url">
</asp:ImageField>
</Columns>
</asp:GridView>

What data viewing control will I need to use?

I am new to asp.net and even though I have been successfully developing some decent pages
that access backend SQL server using C# code behind, I have run into a problem that I need
some nudge in the right direction on.
I need to be able to display records from a SQL datasource (could be displayed using SQLDataSource method
OR using a dataReader OR using a gridview data fill) onto a page but I need other information displayed above
and below the returned record. Its best if I show an example:
<horizontal seperator line>
Customer ID
Customer Name
Customer Address
City, ST
COLUMNS FOR THE RETURNED RECORD DATA
THE ACTUAL RECORD DATA
OTHER DYNAMICALLY CALCULATED DATA BELOW THE RECORDS
<horizontal seperator line>
And this repeats for every record that is returned
For the life of me, I can't find determine what view, template, or even best data binder or
data source control it is that I need to use to make this happen.
Thanks for anyone's assistance in advance.
dell

If a datatable or gridview won't do, you can always use a Repeater or a Listview.
In the template, you can have all the controls you want in there.
You probably need a repeater similar to this:
<asp:Repeater runat="server" ID="repeater1">
<ItemTemplate>
<hr/>
<asp:Label runat="server" ID="labelCustomerId" />
<div style="padding-left:150px">
<asp:Label runat="server" ID="labelCustomerName" />
<asp:Label runat="server" ID="labelCustomerAddress" />
<asp:Label runat="server" ID="labelCityState" />
</div>
<asp:GridView runat="server" ID="gridViewRecordData">
<!--define columns & footer calculations here -->
</asp:GridView>
<hr/>
</ItemTemplate>
</asp:Repeater>
You can use the same ItemTemplate if you chose a ListView

Repeated is the best control. but in repeater you need to write code for Paging, Sorting...etc functiontly.
If you don't want to code for paging, sorting then go for GridView.

Try a ListView control. It lets you use templates to define how records, groups of records, etc. show up. For example you could define a template for your customer contact info, then a template for your records and other data.

You can accomplish this easily with a ListView. This article has a display of product information that's a lot like your layout -- horizontal lines between repeated sections.
I also like Scott Gu's tutorial, though the data layout (catalog images) is a little different from yours. Still, there's some good screenshots, and it also demos a Linq to SQL data source, which is a popular choice.

ObjectDataSource reacts to commented-out GridView?

I came across a very strange behavior in asp.net's ObjectDataSource, the description to reproduce is somewhat long, so bear with me while I set the scene.
So, imagine a trivial ObjectDataSource/GridView combo in a User Control. The ObjectDataSource calls a method which returns a List of objects, and the GridView shows these objects in tabular form:
<div runat="server" ID="ControlWrapper">
<asp:GridView ID="GridView1" AutoGenerateColumns="true" DataSourceID="ObjDataSource1" OnRowDataBound="GridView1_RowBound" runat="server">
</asp:GridView>
</div>
<asp:ObjectDataSource ID="ObjDataSource1" runat="server" SelectMethod="GetBundle" OnSelecting="FixDataSource_Selecting" OnSelected="FixDataSource_Selected"
TypeName="West.VitalSigns.Contracts.ProdFixController">
</asp:ObjectDataSource>
This approach will work with pretty much nothing in the code-behind. But let's say that we want to create n number of GridView-s depending on the contents of the database. So we comment out the GridView in the markup...
<div runat="server" ID="ControlWrapper">
<!--
<asp:GridView ID="GridView1" AutoGenerateColumns="true" DataSourceID="ObjDataSource1" OnRowDataBound="GridView1_RowBound" runat="server">
</asp:GridView>
-->
</div>
...and add something like this to the ObjectDataSource's Selected event handler:
protected void FixDataSource_Selected(object sender, ObjectDataSourceStatusEventArgs args)
{
HashSet<string> components = new HashSet<string<()
foreach (ProdFix fix in (List<ProdFix>)args.ReturnValue)
{
if (!components.Contains(fix.Component))
{
GridView v = new GridView();
v.ID=fix.Component.Replace(" " ,"").Replace("-","");
v.AutoGenerateColumns = true;
v.DataSource = args.ReturnValue;
v.RowDataBound +=new GridViewRowEventHandler(BundleGrid_RowBound);
ControlWrapper.Controls.Add(v);
components.Add(fix.Component);
}
}
}
This code works (or at least the un-simplified version works on my machine), so you decide to remove the commented-out section from the markup (don't want that cruft hanging around, after all!)
<div runat="server" ID="ControlWrapper">
</div>
When you do this, however, the code no longer works! The ObjectDataSource won't fire, which means that the Selected event will never happen, which means you won't get your GridView-s. It looks like ObjectDataSource is reacting to commented-out markup in the aspx file?
So, is this:
A bug in ASP.NET?
A non-standard way of dynamically creating GridViews?
A WTF that I shouldn't have tried anyway?
All of the above?

Your gridview control in the markup is not hidden, even with the comments. HTML comments do not apply to server-side tags. Use server side comments instead:
<% /* %> <% */ %>
or
<%-– and -–%>

24hrs later, I noticed that this approach to getting N number of grid-views was pretty silly. Instead of using an ObjectDataSource I refactored my code to just call the GetBundle method directly from Page_Load() and create the GridViews programatically.
cdonner has the answer correct about the server-side comments. I didn't realize that there was a difference.

This should work too, since you're "disabling" the tag with it:
<!--asp:GridView ID="GridView1" AutoGenerateColumns="true" DataSourceID="ObjDataSource1" OnRowDataBound="GridView1_RowBound" runat="server">
</asp:GridView-->