DevExpress XtraGrid Control - Stop Redraw On Datasource Update - devexpress

Scenario
I am using the latest version of DevExpress XtraGrid.
I am currently binding the DataView of a DataTable to the datasource of the gridcontrol in C#.
Since this DataTable gets updated every second, I have to refresh the gridcontrol.
ALSO
The DevExpress XtraGrid comes with the ability to automatically drag and drop the column headers into a group/sort like manner. This refresh problem I am having is particularly noticeable when I incorporate the use of the "group by column header" feature - In that the data that is grouped is collapsed under a single row. If I expand this row to see the data, it immediately shuts again upon Update - which at the minute is every second, rendering the grouping feature useless.
Question
How can I go about doing this without redrawing the whole thing?
I literally just want to see the numbers dynamically changing AND be able to use the grouping feature continually without it collapsing by itself when the rows of data update.
Current Code
DataView dvw = latestCurve.Tables[0].DefaultView;
dvw.Sort = "Ccy Asc AND Date Asc";
this.gridControl2.DataSource = dvw;

Assuming your default view for gridControl2 is named gridView2:
gridView2.BeginUpdate();
try
{
your code goes here
}
finally
{
gridView2.EndUpdate();
}

Related

Kendo Grid: Prevent datasource refreshing on grid filtering

I got a grid displaying +- 4000 candidates. You can search and filter the grid by typing in a textbox. For each character typed there is a 1.5 second debounce before the grid refreshes/filters with the textbox content as a parameter.
On my local database this works like a charm. But on the live environment there is a big performance issue.
Each time the filter is applied, the Read action is called, all data is fetched and filtered. This means a new request to the server for every character typed.
What I want to achieve is that when filtering, the filtering happens on the data inside the grid, instead of refreshing/reloading the whole datasource on every filter.
How can this be achieved?
This can be simply achieved by setting serverFiltering in DataSource to false.
API Reference

reload table in WatchKit

We have a hierarchical watch app.
The root controller is a table of menu items. That list of items is controlled by a server. The data is retrieved and stored in core data. The menu is populated the first time going into the app.
But I want this table to stay current. My thought was to add code to willActivate to check if there was changes, and reload the table. In my reload logic I call the same function I called the first time, which sets the menuTable.setNumberOfRows and creates each row. Looking at what I'm putting in the logs, it is going through this logic with a different count of rows and new labels. But the app on the watch shows the table with the old data.
How can I get this table to reload with the new information?
I've had this problem too and as rmp says, it still seems to be a bug in watchOS 1.0.1. The problem appears when you try to reload your tableView after run willActivate() and nothing will happen.
In my case, I reload the tableView after receive a reply from a delegate and then I reload all the content just if it's necessary. To achieve this, I remove all rows from a NSIndexSet and load again.
if isNecessary {
self.table.removeRowsAtIndexes(NSIndexSet(indexesInRange: NSMakeRange(0, maxItems)))
isNecessary = false
}
I've tried a lot of tricks but none has worked for me:
Force to reload rows by table.setNumberOfRows(0, withRowType: "data")
Setting parameters to empty text before assign new values
One thing you could do is to hide tableView before removing rows, and avoid the remove animation.
It is a bug in WatchKit. Seems like Apple doesn't handle the repetitive interface object correctly.
The general principle here is: Only insert or remove necessary rows after a table is created. Do not reload the whole table like what we usually do in iOS. It just doesn't work (or trigger the bug).
So specifically, you have to:
Do this in willActivated method. This is correct.
If this is the first load, before the table is even created, do what you are now doing – load all table rows.
For all following times, don't reload the table, fetch the new data and check the desired number of rows.
Compare with the current number of rows in the table, insert to or remove from the bottom of the existing table.
Now simply re-assign the new data to all existing rows. Again, do not reload.
It should work if you follow the above steps.
I have found what works best given the current state of watchkit is to remove all rows then re-populate the table.
Try something like this:
- (void)loadTableData{
//clear the table
[mainTableView setNumberOfRows:0 withRowType:#"myTableRow"];
//set the row count again
[mainTableView setNumberOfRows:numberOfRows withRowType:#"myTableRow"];
//populate table
}
Its pretty simple. As Apple hasn't provided any method to reload the data.
You can still achieve that by simply populating the rows for the tableview.
Below is the sample code:
for index in 0..<tracksTableView.numberOfRows {
if let controller = tracksTableView.rowController(at: index) as? EditPlaylistRowController {
controller.playingTrackId = self.playingTrackID
controller.sharedTrack = trackItems[index]
}
}
Use it whenever you want to refresh the data.
NOTE:
You can still make some conditional statements inside the row controller class.
Happy to help :)

Maintaining Row Selection in ASP.NET GridView Control

The Setup:
I currently have a page with a GridView control on it inside of an update panel, using a SqlDataSource. I have a timer setup to update the GridView every X amount of seconds. Typically for what I am testing every time the GridView updates about 4-5 new rows of data are added to the gridview, while the last 4-5 get tossed out. I am only displaying 15 results at a time and will have new results coming in every update.
The Problem:
I allow the user to select the rows, while the GridView is being updated. I am handling this by setting the SelectedIndex property. However, when I select a row and then the grid is updated the row the user selected gets pushed down about 4-5 rows and the data in the previous selected index is selected instead. So where they clicked is selected at this point, not what they clicked.
I need a way to determine, if possible from the SqlDataSource/Gridview, how many new rows have been added to the gridview. OR a way to maintain the selected data by the data in the row and not just the SelectedIndex.
Any help is appreciated, thanks.
RESOLVED:
Ok I went ahead and added a new invisible column to my grid, and am now keep track of the unique ID's selected from the DB. By setting an array before databinding, and comparing that to the new array I get after databinding I was able to use a simple Intersect to determine the number of rows that are the same. Then I used that to determine from the total how many are new this postback.
Just an idea:
I think you can use an invisible column (more specifically an ID column) to store the selected rows' IDs value in the Session object and then after the grid updates, you can retrieve this value(s) and select the row(s) again if they are still present.
If you have custom GridView OnRowUpdating event.
public void GridView_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
Session["CurrIndex"] = GridView.SelectedIndex;//index before insertion
Session["RowCount"] = GridView.Rows.Count;//row count before insertion
//Add new Rows
GridView.SelectedIndex = (Int32)(Session["CurrIndex"]) + ( GridView.Rows.Count - (Int32)(Session["RowCount"]);//update selected index
Session["CurrIndex"] = GridView.SelectedIndex;//restore the index into session
}

Creating Dynamic Tables in VB.Net

I am new in .Net and I had a question regarding creating dynamic tables.
I am creating a page that adds a new row to a table (First Name, Last Name, Address, etc...) when a user clicks on a button. I have been reading that every time you do a postback to a dynamic table you have to re-create the rows. That is what I am doing.
I have been testing this and about 40 rows have being added already, when I click to add a new row, it runs completely slower and I can only imagine how long it would take to add 100 rows. I am assuming that it is because re-creating the rows takes time.
My questions is there a better approach or another way to accomplish task?
'***Edits Here what im currently doing
This is my table and button control:
Code when button is clicked, which creates the dynamic table:
Dim tblrow As TableRow
Dim tblcell As TableCell
Dim inputText As TextBox
tblrow = New TableHeaderRow
tblcell = New TableHeaderCell
tblcell.Text = tableCount 'variable used to count rows in the table
tblcell.HorizontalAlign = HorizontalAlign.Left
tblrow.Cells.Add(tblcell)
tblcell = New TableCell
inputText = New TextBox
inputText.ID = "txt_" & tableCount
tblcell.Controls.Add(inputText)
tblrow.Cells.Add(tblcell)
table1.rows.add(tblrow)
Now from what I learned and tested so far, everytime I do a postback I have to rebuild this table in order to keep all of the contents I entered into the table.
The next question is why dont you add another row using jquery so that you don't have to do postbacks. I have tried this approach and it worked well UNTIL I needed to put the information entered into the table into a database which required a postback. So I was back at my original problem.
Note, if there is a better way to approach this im all ears. Like I said before I am new to this language and im just trying to learn.
My suggestion for you will be to use the JqGrid it is a free open source jquery plugin but also available commercially. It is fast in data loading and have lots of dynamic features
If you know javascript and jquery then this will be easy for you to use, it comes as Asp.Net, mvc and php component
Are you using windows forms? If you are, use the ListView control and change the view (I believe thats what it's called...) to details. Then you can use one of the many tutorials like this to populate the list:
If not using Windows Forums sorry, I saw the VB.net part and assumed.
asp.net is a server side web technology which means that you are working with a stateless technology (basically). That is why you have to rebuild everything on every postback.
There are several ways of dealing with this:
using the asp.net ViewState and check for Page.IsPostback on PageLoad
using jQuery and clientside Templates like Pure and fetch the Data through webservices
I on your behalf would avoid creating a table manually like you showed above, but instead use templated controls and specify the behavior declaratively.
When you create a DataGrid for example and are using ViewState, you do not have to explicitly recreate the DataGrid, since asp.net is taking care of it when used correctly.

Gridview Edit not working after Sorting ASP.NET

I am using C#,ASP.NET
I have a Gridview for which I have provided Sorting, Edit functionality. I am not able to perform EDIT when I perform Sorting. After sorting edit is set on some other row. I think there is some problem with the index it is taking..
Can any one help me how to fix this..
Regards
sbmarya
I think the issue is that the sorting is using a different call/datasouce than the editing. So in the RowEditing event I am getting an index relative to the sort order (either ASC() or DESC()). But then I am binding using getUsers() which is returning the data in a different order.
What I did is I stored some kind of a flag(Value) in ViewState to indicate what sort order I am in and made use of that when I am binding in the Editing event, so that I can call the right method to return the same datasource.
Regards,
sbmarya
I faced this problem as well. This is how I fixed it. (In my example the gridview is sorted on a column called submit date).
a. When the underlying dataTable of the gridview is crated and sorted store it in a session variable. The trick is, before storing to a session variable make sure you store the sorted view.
dt.DefaultView.Sort = "Submit Date" + " " + "DESC";
GridView1.DataSource = dt;
GridView1.DataBind();
Session["gridViewData"] = dt.DefaultView.ToTable(); //Only storing dt will not have the sorted table stored in session.
b. next, perform all edit/update operation using the dataTable stored in session in the above step. It will always come up in proper sorted order and you will not see the issue of row index changing unexpectedly after update.

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