I have a ASPxGridView and I am using its delete confirmation like:
grdList.SettingsBehavior.ConfirmDelete = true;
grdList.SettingsText.ConfirmDelete = "Record will be deleted. Do you want to continue?";
When the customer hits the delete button
"Specified method is not supported"
is throwed. When I test the page, its works how it should be.
Do you have any idea of what may cause that error? We both use IE.
Thank you.
Specified method is not supported thrown when deleting ASPxGridView row usually indicates that the corresponding command is not specified when the grid control tries to execute delete command against underlying data source. If you're using custom data source, take note to this explanation:
When binding ASPxGridView with custom/non-declarative data sources,
they may not have implemented the CRUD operations logic (i.e., there
are no rules that describe how to automatically update a particular
item).
To fix this issue, you can handle RowDeleting event and set Cancel property to true to cancel updating operation as follows:
protected void grdList_RowDeleting(object sender, DevExpress.Web.Data.ASPxDataDeletingEventArgs e)
{
var grid = sender as ASPxGridView;
// make sure Cancel property set to true
e.Cancel = true;
// row deleting code here
// data rebinding code here
grdList.DataBind();
}
Note that Cancel property should always be set to true, either in finally block or before any part of code which potentially raise exception.
protected void grdList_RowDeleting(object sender, DevExpress.Web.Data.ASPxDataDeletingEventArgs e)
{
var grid = sender as ASPxGridView;
try
{
// row deleting code here
// data rebinding code here
grdList.DataBind();
}
catch (Exception e)
{
// exception handling
}
finally
{
// make sure Cancel property set to true
e.Cancel = true;
}
}
Additional references:
Specified method is not supported on deleting GridView row
How to implement CRUD operations with a custom data source
Related
I am working on a .net 4.6.1 C# winforms project that has a datagridview where users can change the order of columns.
I would like to store the new order in a db table, but have trouble finding the right event for detecting when a user changed the order of the columns.
After searching here, I was pointed to the DataGridView.ColumnDisplayIndexChanged event in this thread. But that one does not solve my issue. (it only gives a solution for multiple events when you fill the datagrid view, but that is answered easily by adding the handler after setting the datasource)
That sort of works, but gets fired multiple times when a user changes the order of columns (it f.e. looks like when changing columns A,B,C,D to D,A,B,C the event gets fired 3 times (probably for A,B,D,C - A,D,B,C - D,A,B,C)
I am having a hard time finding out how I can detect if the event is the final one (since I don't want to store all these new orders, only the final one)
My questions are:
Is this event the 'best' one to use for my case?
If so, how can I detect the final ColumnDisplayIndexChanged event (D,A,B,C)?
When you reorder columns, ColumnDisplayIndexChanged will raise for all the columns which their display index has been changed. For example if you move colum A to the position after C, the event will raise for all those three columns.
There is a solution to catch the last one. DataGridViewColumn has an internal property called DisplayIndexHasChanged which is true if the event should be fired for the column. The private method which raise the event, looks into list of the columns and for each column if that property is true, first sets it to false, then raises the event. You can read internal implementations here.
You can check if there is no column having DisplayIndexHasChanged with true value, you can say it's the last event in the sequence:
private void dgv_ColumnDisplayIndexChanged(object sender, DataGridViewColumnEventArgs e)
{
var g = (DataGridView)sender;
var property = typeof(DataGridViewColumn).GetProperty("DisplayIndexHasChanged",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
if (g.Columns.Cast<DataGridViewColumn>().Any(x => (bool)property.GetValue(x)))
return;
else
MessageBox.Show("Changed");
}
Just keep in mind, you should disable capturing that event when you add columns:
private void f_Load(object sender, EventArgs e)
{
LoadData();
}
void LoadData()
{
dgv.ColumnDisplayIndexChanged -= dgv_ColumnDisplayIndexChanged;
dgv.DataSource = null;
var dt = new DataTable();
dt.Columns.Add("A");
dt.Columns.Add("B");
dt.Columns.Add("C");
dgv.DataSource = dt;
dgv.ColumnDisplayIndexChanged += dgv_ColumnDisplayIndexChanged;
}
My suggestion would be not to do any custom logic to find out if its the last one or something along those lines. The best approach would be to save after each event but you can debounce it.
Using a debounce approach you can cancel the old event if the new event is fired right after depending on some amount of time you wish to allow inbetween calls.
Ex: write to storage only if there is no new event after lets say 1 second or 5 seconds depending on what is accepteable for your application
Say we decide to save with a debounce of 1 second
First event occurs you trigger the action which has 1 second to execute
If another event is triggered the old action is ignored and the new action now has 1 second to execute and so on for other sequential actions
public static Action Debounce(this Action func, int milliseconds = 300)
{
var last = 0;
return arg =>
{
var current = Interlocked.Increment(ref last);
Task.Delay(milliseconds).ContinueWith(task =>
{
if (current == last) func(arg);
task.Dispose();
});
};
}
Assuming the following action below for saving your data
Action a = (arg) =>
{
save my data here
};
first assign the debouncer to your action
var debouncedWrapper = a.Debounce(1000); //1 sec debounce
Then you can use it as follows
public void datagridchangeevent(object sender, Event e)
{
debouncedWrapper()
}
This will ignore sequential calls and the aciton will be executed only if nothing is called for one second
I'm assigning list to e.Result in LinqDataSource OnSelecting Event result contains 5 rows in it. On Execution of OnSelected Event the result doesn't contains any rows . Why is this happening ?... I'm I missing any thing? Here is my code of Selecting event
protected new void OnDataSourceSelecting(object sender, LinqDataSourceSelectEventArgs e)
{
int AdminAccessID = 1;
List<VIEW_ManagerOwned> result = _dataContext.VIEW__ManagerOwneds.Where(ma => (ma.LastName == "West") & (ma.FirstName == "Stacie") & ma.AdminUserAccessID == Convert.ToInt32(AdminAccessID) & ma.SecurityUserID == Convert.ToInt32(1766)).ToList();
e.Result = result;
}
protected void ListLinqDataSource_Selected(object sender, LinqDataSourceStatusEventArgs e)
{
}
I'm no expert on LinqDataSourceSelectEventArgs but my suspicion is that you are expecting the value of e.Result to be passed to the next event hander, in this case ListLinqDataSource_Selected but it is likely that this handler is getting a different set of event args which would explain why you are not getting your list in e.Result from the Selecting handler.
One potential solution is to cache the value of result in a class level variable so that you can access it after you have it populated.
Again I could be wrong about the event handler not sending the previous event args to the next handler, but I believe this is the most likely cause of the issue.
ADDITIONS:
Simply regarding your code, are you sure you want to use bitwise & in your LINQ statement and not a conditional &&? There are times to use each but you may get undesired results using the & operator here. Also, consider formatting your code with less horizontal space and more vertical space, it is difficult to read when you have such a long line of code. Also generally you do not want to assign to event args the way you are doing it, as you can see it is not producing the results you are expecting. (no pun intended on results).
Background:
In my winforms form, I have a Checked ListView and a "master" checkbox called checkBoxAll.
The behaviour of the master is as follows:
If the master is checked or unchecked, all ListViewItems must change accordingly.
If the user unchecks a ListViewItem, the master must change accordingly.
If the user checks a ListViewItem, and all other ListViewItems are checked aswell, the master must change accordingly.
I have written the following code to mimic this behaviour:
private bool byProgram = false; //Flag to determine the caller of the code. True for program, false for user.
private void checkBoxAll_CheckedChanged(object sender, EventArgs e)
{
//Check if the user raised this event.
if (!byProgram)
{
//Event was raised by user!
//If checkBoxAll is checked, all listviewitems must be checked too and vice versa.
//Check if there are any items to (un)check.
if (myListView.Items.Count > 0)
{
byProgram = true; //Raise flag.
//(Un)check every item.
foreach (ListViewItem lvi in myListView.Items)
{
lvi.Checked = checkBoxAll.Checked;
}
byProgram = false; //Lower flag.
}
}
}
private void myListView_ItemChecked(object sender, ItemCheckedEventArgs e)
{
//Get the appropiate ListView that raised this event
var listView = sender as ListView;
//Check if the user raised this event.
if (!byProgram)
{
//Event was raised by user!
//If all items are checked, set checkBoxAll checked, else: uncheck him!
bool allChecked = true; //This boolean will be used to set the value of checkBoxAll
//This event was raised by an ListViewItem so we don't have to check if any exist.
//Check all items untill one is not checked.
foreach (ListViewItem lvi in listView.Items)
{
allChecked = lvi.Checked;
if (!allChecked) break;
}
byProgram = true; //Raise flag.
//Set the checkBoxAll according to the value determined for allChecked.
checkBoxAll.Checked = allChecked;
byProgram = false; //Lower flag.
}
}
In this example, I use a flag (byProgram) to make sure an event was caused by the user or not, thereby preventing an infinite loop (one event can fire another, which can fire the first one again etc. etc.). IMHO, this is a hacky solution.
I searched around but I couldn't find a MSDN documented method to determine if an User Control Event was directly fired thanks to the user. Which strikes me as odd (again, IMHO).
I know that the FormClosingEventArgs has a field which we can use to determine if the user is closing the form or not. But as far as I know, that is the only EventArg that provides this kind of functionality...
So in summary:
Is there a way (other than my example) to determine if an event was fired directly by the user?
Please note: I don't mean the sender of an event! It won't matter if I code someCheckBox.Checked = true; or manually set someCheckBox, the sender of the event will always be someCheckBox. I want to find out if it is possible to determine whether it was through the user (click) or by the program (.Checked = true).
Aaand also: 30% of the time it took to write this question was to formulate the question and the title correctly. Still not sure if it is a 100% clear so please edit if you think you can do better :)
No, there's no practical way to determine whether the change came from GUI or was done by program (in fact, you could analyze the callstack - but that's not recommended because it's very slow and error-prone).
BTW, there's one other thing you could do instead of setting byProgram. You could remove and add the event handler prior or after, respectively, change your controls:
checkBoxAll.CheckedChanged -= checkBoxAll_CheckedChanged;
// do something
checkBoxAll.CheckedChanged += checkBoxAll_CheckedChanged;
Instead of using the changed event, you could use the clicked event to cascade the change through to the relevant controls. This would be in response to a user click, and not the value being changed programatically.
This is something I come across quite a lot and what I tend to try do is not split it between user interaction vs program interaction - I use more generic code i.e. the UI is being updated and doesn't require any events to be handled. I usually package this up through BeginUpdate/EndUpdate methods e.g.
private int updates = 0;
public bool Updating { get { return updates > 0; } }
public void BeginUpdate()
{
updates++;
}
public void EndUpdate()
{
updates--;
}
public void IndividualCheckBoxChanged(...)
{
if (!Updating)
{
// run code
}
}
public void CheckAllChanged(...)
{
BeginUpdate();
try
{
// run code
}
finally
{
EndUpdate();
}
}
I am working with a DataGridView, and I use the CellValueChanged event.
I dont want this event to be triggered when I change a cell value by the code. However, I want it to be triggered when the user edits it.
That's why I enclose my cell value change operations with the following code :
void changeCellOperation()
{
dgv.CellValueChanged -= new DataGridViewCellEventHandler(dgv_CellValueChanged);
...
cell.Value = myNewCellValue
...
dgv.CellValueChanged += new DataGridViewCellEventHandler(dgv_CellValueChanged);
}
I ended to have several differents functions where my DataGridView cells are updated this way.
Because these functions are called from different places and can be nested, I cannot afford to keep this code as is to avoid event unwanted event reactivation.
So I ended up this way :
int valueChangedEventMask = 0;
void changeCellOperation()
{
valueChangedEventMask++;
...
cell.Value = myNewCellValue
...
valueChangedEventMask--;
}
void dgv_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
if (valueChangedEventMask > 0)
return
...
}
This works fine. Also when the calls are nested, including inside the event itself.
But the CellValueChanged event is now fired too many times for no reasons.
Because I often have to cope with this pattern, I am looking for a solution that can be applicable generally for Events in UIs, not only the DataGridView.
So my question is:
What is the best tip to mask UI Events correctly and avoid unnecessary Events fires ?
CellValueChanged is not an UI event, but a property changed event. That means you can not use it to distinguish user input from programmatic change. You can always use subscriber/unsucscribe or flag+/- or BeginEdit/EndEdit-similar technique, but maybe you have to find another (better) approach. To example, in case of checkbox you can use Click event instead of Changed, because (surprise!) it will tell you when the user click it and otherwise safely change value of Checked programmatically.
In case of DataGridView easiest would be to use Changed with some flag (which will be set when edit begins and reset when ends - see, CellBeginEdit/CellEndEdit ).
You could use CellEndEdit instead of CellValueChange. I don't know what your method dgv_CellValueChanged does, just be careful that CellEndEdit is fired every time you exit the edit mode for the cell, even if its value has not been changed. This means that you have to keep trace of the current values of your cells if you don't want the method to be executed when the value doesn't change.
I would avoid events related with the mouse such as CellClick because your users could use just the keyboard.
Anyway I usually avoid this kind of problems by separating the logic from the user interface, i.e. I write a separate class which is bound to the form. Take a look at MVVM (you can implement your own version in WinForms if you want) or the good old MVC.
I ended up mixing both solutions in a very simple one. I use a counter and I only hook/unhook the events I want to mask.
EventMask valueChangedEventMask;
// In the class constructor
valueChangedEventMask = new EventMask(
() => { dgv.CellValueChanged += new DataGridViewCellEventHandler(dgv_CellValueChanged); },
() => { dgv.CellValueChanged -= new DataGridViewCellEventHandler(dgv_CellValueChanged); }
);
// The value change operation I want to hide from the event
void changeCellOperation()
{
valueChangedEventMask.Push();
...
cell.Value = myNewCellValue
...
valueChangedEventMask.Pop();
}
// The class
public class EventMask
{
Action hook;
Action unHook;
int count = 0;
public EventMask(Action hook, Action unHook)
{
this.hook = hook;
this.unHook = unHook;
}
public void Push()
{
count++;
if (count == 1)
unHook();
}
public void Pop()
{
count--;
if (count == 0)
hook();
}
}
I have a form representing a survey that is dynamically generated based on some database configuration. I have a custom server control for rendering the survey (SurveyRenderer) which contains custom server controls for rendering questions (QuestionRenderers). I dynamically add RequiredFieldValidators for questions if they are flagged as being required. I add these validators to the SurveyRenderer's control collection.
The gist of the code...
// In SurveyRenderer.CreateChildControls()...
foreach (QuestionRenderer questionRenderer in questionRenderers)
{
if (questionRenderer.Question.IsRequired)
{
Controls.Add(CreateRequiredValidator(questionRenderer));
}
}
The client-side validation works fine -- if someone has omitted a required question, the validators catch it and the form doesn't validate. However if I turn off JavaScript and submit an invalid form, the validators do not seem to work.
On the server-side I am calling Page.Validate() and checking Page.IsValid in the submit button click event handler. Despite submitting a form where required questions have been left blank - something that would be caught client-side - on the server-side Page.IsValid remains True.
// In SurveyPage.aspx...
public void btnSubmit_Click(object sender, EventArgs e)
{
Page.Validate();
if (Page.IsValid)
{
// Always get here, even though the form is not valid and would
// have been caught client-side...
}
}
Should I be adding the validators to the Page's Control collection, rather than the SurveyRenderer? How come it works on the client-side but not server-side?
UPDATE: My QuestionRenderer is annotated with:
[ValidationProperty("IsValid")]
And the IsValid get method is like so:
// QuestionRenderer.IsValid
public bool IsValid
{
get
{
EnsureChildControls();
if (Question.IsRequired && QuestionIsNotAnswered())
{
return false;
}
return true;
}
}
If I set a breakpoint and step through, I can see that QuestionRenderer.IsValid is being fired OK. It is returning false when it should do. If I go fine-grained and call in btn_submitClick:
// In SurveyPage.aspx...
public void btnSubmit_Click(object sender, EventArgs e)
{
foreach (IValidator validator in Page.Validators)
{
validator.Validate(); // this calls through to QuestionRenderer.IsValid, which returns false...
bool valIsValid = validator.IsValid; // yet this is set to True
}
}
So validator.IsValid is true, even though the call to QuestionRenderer.IsValid returns false. So maybe I haven't wired something up correctly? Is using [ValidationProperty("IsValid")] not enough?
actually, validation uses Page.Validators where all the validators are stored (the actual routine is quity tricky) - so it does not matter, where you add them.
source of BaseValidator
protected internal override void OnInit(EventArgs e)
{
base.OnInit(e);
this.Page.Validators.Add(this);
}
i would leave them in th view, as you could use object sender-parameter (which represents the validator) to get the associated control ...
i believe, your CreateChildControls - which does the attaching of the validators - is called to late, so it misses the validation phase ...
could you maybe try to call EnsureChildControls in OnLoad-event, to see if it changes something?
another chance might be, that your validators are not visible or disabled...
EDIT
according to your edits, i would encourage you to use a CustomValidator - a RequiredFieldValidator will return true on each case (property is true or false), because it is not empty :)