Telerik RadGrid GridDataItem - how to determine if column exists? - asp.net

I'm using a base class to modify the behavior of any Telerik RadGrid that appears on my ASP.Net pages. In the base class, I want to perform certain operations (set Css, tool tips, etc) on many common columns, but not every common column exists in every grid.
In the ItemDataBound event I'm getting an instance to the GridDataItem and in turn I want to get a reference to one or more of the contained cells of the GridDataItem:
var cell = gridDataItem["ColumnUniqueName"]
Problem is that this throws a GridException if the named column doesn't exist:
Cannot find a cell bound to column name 'ColumnUniqueName'
Is there a way to test for existence of a column by name before referencing it or am I
stuck using try catch?

Will sent me on the right path:
var tableView = gridDataItem.OwnerTableView;
var gridColumn = tableView.Columns.FindByUniqueNameSafe(uniqueName);
if (gridColumn != null)
{
var cell = gridDataItem[gridColumn];
...

Try using the RenderColumns collection:
protected void rgGrid_ItemDataBound(object sender, GridItemEventArgs e)
{
if (e.Item is GridDataItem)
{
bool found = (from d in rgGrid.MasterTableView.RenderColumns select d).Any(d => d.UniqueName == "ColumnUniqueName");
}
}

Related

DevExpress XtraGrid - Change/disable a cell in column2 when column1 changes

I have 2 columns I'm working with in an XtraGrid. When Column1's value changes, I'd like to perform some logic and possibly change the value of Column2 and disable Column2 as well. You can see my code below, but I have 3 problems:
My CustomRowCellEdit function seems to run non-stop in the background.
The SetRowValue on Column2 doesn't seem to really happen unless I click away from the row; I need the change to happen as soon as Column1 is changed.
How can I disable within my IF block?
I've added the following Event to a Grid:
this._myGridView.CustomRowCellEdit +=
new DevExpress.XtraGrid.Views.Grid.CustomRowCellEditEventHandler(
this.myGridView_CustomRowCellEdit);
Here is the Event:
private void myGridView_CustomRowCellEdit(object sender, CustomRowCellEditEventArgs e)
{
if (e.Column.FieldName == "Column1" && e.RowHandle >= 0)
{
GridView gv = sender as GridView;
string value1 = gv.GetRowCellValue(e.RowHandle, gv.Columns["Column1"]).ToString();
if (value1 == "something")
{
gv.SetRowCellValue(e.RowHandle, gv.Columns["Column2"], someOtherValue);
// I'd like to disable Column2 in this IF logic.
}
}
}
In the DevX docs, there is a note about the CustomRowCellEdit event that says
Due to the XtraGrid control's infrastructure, the CustomRowCellEdit event fires frequently - each time a cell is refreshed. Therefore, do not implement complex logic for your CustomRowCellEdit event handler...
Given your stated requirements, my approach would be to use the CellValueChanged event instead of CustomRowCellEdit. Your handler could then say something like
private void myGridView_CellValueChanged(object sender, CellValueChangedEventArgs e) {
if (e.Column.FieldName != "Column1") return;
GridView gv = sender as GridView;
if (e.Value == "something") {
gv.SetRowCellValue(e.RowHandle, gv.Columns["Column2"], someOtherValue);
}
}
To make an individual cell non-editable at runtime, see this topic on the DevExpress support site.
how to set readyonly for rows at runtime using Devxpress Grid Contorl.
Essentially what you need to do is handle the grid view's ShowingEditor event, and using the FocusedRowHandle and FocusedColumn properties, decide whether or not to allow editing for the current cell. To disable editing, set the Cancel property of the CancelEventArgs to true.
Hope this helps.

Two way binding with custom expression?

I am using a gridview in my asp.net project to view and modify some records from the database. The database has two columns: start_date and end_date. When a new record is created these columns contains null, but they can be modified later using the gridview update command.
In gridview I have two template fields (having names start_date and end_date) in which I have placed two calendar controls. Upon clicking an update link of gridview it always returns an error because of the null value binding to the calendar. I have used this helper function to solve it:
protected DateTime ReplaceNull(Object param)
{
if (param.Equals(DBNull.Value))
{
return DateTime.Now;
}
else
{
return Convert.ToDateTime(param);
}
}
and used these two custom expressions in calendar control's SelectedDate:
ReplaceNull(Eval("start_date"))
ReplaceNull(Eval("end_date"))
The problem is that two-way data binding the calendars upon selecting a date does not update the database table. Are there any workarounds? Or alternatively, a better solution would be appreciated.
I don't know why you let them null when insert a new record , but many ways you can solve this problem i think .
one of them : in the RowDataBound event of the Gridview
protected void gv_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
if (e.Row.Cells[1] == null) //the index of the start_date
{
e.Row.Cells[1].Text = DateTime.Now.ToString(); // in your case you will make the selected date of the calender(through casting to calender) with the value you need.
}
}
}
Or: you can catch the exception , you meet in your Update button through
try and catch block.

Gridview cell value and array list

When I am tryng to pass the gridview cell values to an array everything is perfect but the array is empty after executing the code.
When I see through debug mode the index of selected row also is fine, i.e. when I select two rows using checkbox among 1000 the count shows exactly 2 in the array but the data is empty.
I'm not able to get the cell value from the gridview.
Any advice would be greatly appreciated.
protected void Button2008_Click(object sender, EventArgs e)
{
ArrayList checkedItems = new ArrayList();
foreach (GridViewRow row in this.GridView1.Rows)
{
if (((CheckBox)row.FindControl("cbRows")).Checked == true)
{
checkedItems.Add(row.Cells[12].Text);
}
}
Session["CheckedItems"] = checkedItems;
Response.Redirect("About.aspx", true);
}
you can use a breakpoint and check where the problem is occuring, for instance, does row.Cells[12].Text show any value ?
and you can check how your aspx page is acting after the postback.

How can I retrieve a subset of data from entity object data source and pass to another page

I am playing about just now trying to teach myself a little bit about the entity framework.
I have a Gridview data bound to a Entity Date Source using the Entity Framework. If I select certain items in that list I then wish to redirect another page and populate another gridview with just the items selected (but with more detail, different includes/navigation properties)
This is probably the most simple thing but I have spent 2 hours banging my head on the wall trying to get this to work.
Essentially I have a continue button which when clicked should identify all the UIDs (a column in the gridview) of the rows and allow me to subset to just these rows and pass them to another page to be rebound to another datagrid
Any ideas???
Well, the big picture is that you should get those IDs, pass them to the other page, and then use a query with Contains; see this question for an idea of how to use it:
How search LINQ with many parametrs in one column?
Assuming you haven't used DataKeys in your GridView, this would be my approach.
Page 1
protected void Button1_Click(object sender, EventArgs e)
{
var checkedItems = new List<int>();
foreach (GridViewRow row in GridView1.Rows)
{
var checkbox = (CheckBox)row.FindControl("CheckBox1");
if (checkbox.Checked)
{
checkedItems.Add(int.Parse(row.Cells[1].Text));
}
}
Session["checkedItems"] = checkedItems;
Response.Redirect("Page2.aspx");
}
Page 2
protected void Page_Load(object sender, EventArgs e)
{
var checkedItems = (List<int>)Session["checkedItems"];
Session["checkedItems"] = null;
foreach (var checkedItem in checkedItems)
{
Response.Write(checkedItem);
}
}
Using the IDs in the checkedItems List you can now query those from you DB and finally assign the Result to your GridView on the second page.
Instead of using Session you could pass the IDs via QueryString.

Selectively apply css to a row in a gridview

I'm looking for a way to selectively apply a CSS class to individual rows in a GridView based upon a property of the data bound item.
e.g.:
GridView's data source is a generic list of SummaryItems and SummaryItem has a property ShouldHighlight. When ShouldHighlight == true the CSS for the associated row should be set to highlighted
any ideas?
very easy
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
DataRowView drv = e.Row.DataItem as DataRowView;
if (drv["ShouldHighlight"].ToString().ToLower() == "true")
e.Row.CssClass = "highlighted";
}
}
the code above works if you use a DataTable as DataSource
change to:
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
myClass drv = (myClass)e.Row.DataItem;
if (drv.ShouldHighlight)
e.Row.CssClass = "highlighted";
}
}
just for the example above when using generics:
public class myClass
{
public Boolean ShouldHighlight
{ get; set; }
}
if you are working with Generics (List, Dictionary, etc)
keep in mind:
e.Row.dataItem
always return the entire object that you are populating the row with, so it is easy from here to manipulate the appearance of the data in the webpage.
you should use RowDataBound event that will trigger after the data is attached to the row object but not yet written the HTML code in the page, in this way you can check the ShouldHighlight value (I converted to a String cause I do not know the type, you can change it if you know it's a boolean value).
this code runs much faster than megakemp code cause you're not creating a List object and populated with the entire data source for each row...
P.S. take a look at this website, you can find several tutorials for your project using the GridView object
One thing you want to keep in mind is that setting the Row.CssClass property in the RowCreated or RowDataBound event handlers will override any default styles you may have applied at the grid level. The GridView gives you easy access to row styles via properties such as:
gvGrid.AlternatingRowStyle.CssClass = ALTROW_CSSCLASS
gvGrid.RowStyle.CssClass = ROW_CSSCLASS
However, when you assign a CssClass value to a specific row, as is your need in this case, the assignment overrrules any top-level assignment at the grid level. The assignments will not "cascade" as we might like them to. So if you want to preserve the top-level class assignment and also layer on your own, more specific one, then you would need to check the rowState to see what kind of row you are dealing with and concatenate your class names accordingly
If(item.ShouldHighlight)
{
If(e.Row.RowState == DataControlRowState.Alternate)
{
e.Row.CssClass = String.Format("{0} {1}", "highlight", ALTROW_CSSCLASS)
}
else
{
e.Row.CssClass = String.Format("{0} {1}", "highlight", ROW_CSSCLASS)
}
}

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