Develop Reference

Modifications to the default behavior in Syncfusion Blazor Grid

I have a grid that is working for me, but my Customer has a requirement pretty different to the default behavior. I'm now very pressed to perform this changes ASAP.
The grid has a checkbox column and multiselection is enabled. The user can select a row only through the checkboxes. For the sake of brevity, I'll copy here the settings.
<SfGrid #ref="Grid" DataSource="Coberturas" Width="100%" EnablePersistence="true">
<GridSelectionSettings Type="SelectionType.Multiple" CheckboxMode="CheckboxSelectionType.Default" CheckboxOnly="true"></GridSelectionSettings>
<GridEditSettings AllowAdding="false" AllowDeleting="false" AllowEditing="true" AllowEditOnDblClick="false" AllowNextRowEdit="false"></GridEditSettings>
It has no toolbar. You can't add rows, nor deleting them. EnablePersistence is needed for reasons out of this question. There is a Primary Key column, but it is hidden (Visible is false). About the rest of the columns, they are text columns.
The customer has asked to change the default behavior in the following way:
When the user clicks a checkbox, the row must both select and open
for editing.
After changing values, the edition boxes must remain
open, even if the user press Enter or clicks another row.
If the user clicks another row, this new row must both select and open for
editing. Even if it's not possible to kept the previous row with the
boxes open (I'm in doubt about if this is possible in the Syncfusion
grid), the previous selection must be kept. All selections must not
be lost, even if the user confirms the edition or moves to another
row.
Illustrative image of the requirements
I'm pretty new to Syncfusion controls and I have no idea how to perform this requirement. I suppose I must create handlers for some Grid Events (maybe RowSelected or OnRecordClick?) but I also may have to interrupt the default Selection and Editing behavior and I don't know how to do this. Because the pressure I have, any idea would be highly appreciated.

You can achieve this requirement by using the RowSelected and OnActionComplete events of Grid. Call the StartEdit method in RowSelected event handler to enable edit in a single click. And in the OnActionComplete event handler based on the RequestType as BeginEdit you can select the required rows based on the stored selected rows indexes from RowSelected event handler.
Sample : https://www.syncfusion.com/downloads/support/directtrac/general/ze/ServerApp-614805550
Please refer the codes below,
<GridEvents RowSelected="RowSelected" OnActionComplete="OnActionComplete" TValue="Order"></GridEvents>
public List<double> SelectIndexes = new List<double>();
SfGrid<Order> Grid;
public bool flag { get; set; } = true;
public async Task RowSelected(RowSelectEventArgs<Order> args)
{
if (flag)
{
await Grid.StartEdit();
SelectIndexes.Add(args.RowIndex);
}
flag = true;
}
public async Task OnActionComplete(ActionEventArgs<Order> args)
{
if (args.RequestType.Equals(Action.BeginEdit) && SelectIndexes.Count != 0)
{
flag = false;
await Grid.SelectRows(SelectIndexes);
}
}
References :
https://blazor.syncfusion.com/documentation/datagrid/events/#onactioncomplete
https://help.syncfusion.com/cr/blazor/Syncfusion.Blazor.Grids.SfGrid-1.html#Syncfusion_Blazor_Grids_SfGrid_1_StartEdit
https://blazor.syncfusion.com/documentation/datagrid/editing/#event-trace-while-editing

My method only works when called from one particular area of my application [duplicate]

I have tried to get an answer to this but so far no help has been able to do what I want it to.
I have this piece of code, which is meant to look at the selected row and output it's columns into the corresponding text boxes.
private void DataGridView01_SelectionChanged(object sender, EventArgs e)
{
if (DataGridView01.SelectedRows.Count > 0)
{
personIDTextBox.Text = DataGridView01.SelectedRows[0].Cells[0].Value.ToString();
comboBox1.Text = DataGridView01.SelectedRows[0].Cells[1].Value.ToString();
Txt_FirstName.Text = DataGridView01.SelectedRows[0].Cells[2].Value.ToString();
mIDDLENAMETextBox.Text = DataGridView01.SelectedRows[0].Cells[3].Value.ToString();
sURNAMETextBox.Text = DataGridView01.SelectedRows[0].Cells[4].Value.ToString();
cITYTextBox.Text = DataGridView01.SelectedRows[0].Cells[5].Value.ToString();
eMAILTextBox.Text = DataGridView01.SelectedRows[0].Cells[6].Value.ToString();
}
}
When I launch the program, I get no errors but it doesn't output the data into the textbox. Anyone know what I am doing wrong?

HOOKING UP EVENTS:
It is the most basic thing you need to learn to code in VS. In short it means that the event name, here DataGridView01_SelectionChanged is connected to the event. To do so one can either use code or one inserts it into the correct slot of the events pane of the property tab. Select the DataGridView, open the events pane (the one with the flash) and locate the SelectionChanged event! Here insert the name of the event and you are done.
(I only have the German versions of VS installed..)
The result is reflected in the form_designer.cs file and it is the same thing (in reverse) as double clicking that spot and then filling in the generated code stub..
Controls have many events; one is the default event and this can be generated by double clicking the control itself in the designer. But eventually you will need all 3 ways to generate and hook up the events, (as well as sometimes removing them.)

I use a slightly different approach when trying to get data from a datagridview.
Try doing personIDTextBox.Text = DataGridView01.SelectedCells[0].Value.ToString();
but instead of the event being on selection change, switch to CellClick and change the property of the the datagridview row selection property to full row select. after that you can change the SelectedCell[0] number to match whichever cell you want

If you want to display the datagridview selected rows into corresponding textboxes, fine the below steps ,
Step 1:
1. Change the DataGridView Selection mode to FullRowSelect in Datagridview property.
2. Create the cell click event in Data grid view using property.
enter image description here
3. Write the below code and test it, It may helpful
private void DataGridView01_CellClick(object sender,DataGridViewCellEventArgs e)
{
if (DataGridView01.Rows.Count > -1)
{
PersonIdTextBox.Text=DataGridView01.Rows[e.RowIndex].Cells[0].Value.ToString();
comboBox1.Text = DataGridView01.Rows[e.RowIndex].Cells[1].Value.ToString();
Txt_FirstName.Text = DataGridView01.Rows[e.RowIndex].Cells[2].Value.ToString();
mIDDLENAMETextBox.Text = DataGridView01.Rows[e.RowIndex].Cells[3].Value.ToString();
sURNAMETextBox.Text = DataGridView01.Rows[e.RowIndex].Cells[4].Value.ToString();
cITYTextBox.Text = DataGridView01.Rows[e.RowIndex].Cells[5].Value.ToString();
eMAILTextBox.Text = DataGridView01.Rows[e.RowIndex].Cells[6].Value.ToString();
}
}

Retrieving last saved value in C# WinForms

Suppose I have one form where a combo box has some options. Now, at the first run of this program, user selects a option from combo box and saved it through a button click or something. Now, If user terminates the application and run again for the 2nd time, is there any way to retrieve the last saved selection?
That means, if you select option1 from the combo box and terminate the application. after some time, you again start the application, now your combo box should show option1 as selected because at the previous session, you selected it.
I hope you'll understand what i think.

Use Settings
// To Load (after combo box binding / population)
private void LoadSelection()
{
int selectedIndex = 0;
if (int.TryParse(Properties.Settings.Default.comboBoxSelection, out selectedIndex))
{
cbMyComboBox.SelectedIndex = selectedIndex;
}
}
// saving on button click.
private void saveButton_Click(object sender, EventArgs e)
{
//set the new value of comboBoxSelection
Properties.Settings.Default.comboBoxSelection = cbMyComboBox.SelectedIndex;
//apply the changes to the settings file
Properties.Settings.Default.Save();
}
See here for more detail.

You have to manually save the value and load it up again when the program starts.
The easy way to do it with Visual Studio is to create a Settings class. In VS, right click your project, click add new, scroll to "Settings File", add. VS will show you a UI where you can create new properties in the settings object that you can chose the name of.
If I create a new property called "ComboboxValue" of type string, I can reference it in the code as Settings1.Default.ComboboxValue = "hello world";
Here's the MSDN on it:
http://msdn.microsoft.com/en-us/library/a65txexh(v=vs.100).aspx

You can add settings
on solution explorer under the project, properties folder
add resource "string" give it a name "selected" for example
then
// this is save button
Properties.Settings.Default.selected = comboBox1.SelectedIndex;
Properties.Settings.Default.Save();
// this is retrieve (use it in window_load event for example)
comboBox1.SelectedIndex = Convert.ToInt32(Properties.Settings.Default.selected);

How can I get a dynamically generated drop down choices for a text field in C#?

I want to have a text field in a C# winform application, and the effect I want is that as the user types stuff in the text field, the program searches a database in the background, and then generates a drop down list for the user to choose from ..
Here are two web based examples but do note that my application is winforms based, not web-based .. I just want the same effect, which is why I'm showing these:
cinemasquid.com:
blu-ray.com:
How can I get the same effect for a text field in a C# winform application ?

First you will need to bind TextChanged event on the form. Then when user press any key, you will get the event. Now inside event handler retrieve the string entered by the user, using this string you perform the search (don't do the search on UI thread, else your UI will hang, you can do the search in BackgroudWorker (MSDN)). Once you get the result, bind this result to ListBox.
I had developed one application, which has autocomplete feature. In this if user enter any movie name, matching results use to be displayed in the list box.
Hope this works for you.

If you don't want to code your solution there are a handful of custom controls avaliable via Google search, for example: http://www.dotnetfunda.com/articles/article225.aspx
BUT you should keep response times in mind: if you code a database search everytime the user enters a letter on your textbox, your application could get sluggish and/or unresponsive, depending on number of records on the table, speed of your network connection and a lot of other factors.
Consider preloading a collection of strings (name, titles, whatever it is you want to display on the textbox) on memory and then performing LINQ queries to that in-memory collection to populate the autocomplete part of your control.

As Amar Palsapure say, You need to use TextChanged Event of You DropDown. Also, Background worker will be also welcome.
Here is a short example:
First, we need some data source. In this case, this will be a simple list of strings:
List<string> DataSource = new List<string>
{
" How do I use jQuery to select all children except a select element",
"How can I get the text of the selected item from a dropdown using jQuery?",
"Dropdown menu in IE6 inserting too much width, not dropping-down",
"How to display images within a drop down box instead of text",
"InfoPath 2007 - Populate drop-down list on-the-fly",
"Is there any difference between drop down box and combo box?",
"Drop Down list null value not working for selected text c#?",
"Make drop-downs automatically drop in a loop cycle",
"PHP How can I keep the selected option from a drop down to stay selected on submit?",
"Jquery Issue - Drop down list does NOT show from iPhone/Mobile Devices"
};
next, BackgroundWorker DoWork Event - this is part response for searching valid position in our Data Source:
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
String text = e.Argument as String;
List<String> results = new List<string>();
//Code for seraching text - may be diffrent if you have another DataSource
foreach (String dataString in DataSource)
{
if (dataString.IndexOf(text, 0, StringComparison.CurrentCultureIgnoreCase) != -1)
{
results.Add(dataString);
}
}
e.Result = results;
}
You can see, that Result is returning by e.Result, So we need to implement RunWorkerCompleted event too:
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
comboBox1.Items.AddRange((e.Result as List<String>).ToArray());
comboBox1.DroppedDown = true;
}
This code will fill our dropDown witch returned values, and show it to user.
Of course, to make this run, you need to call RunWorkerAsync in TextChanged:
private void comboBox1_TextChanged(object sender, EventArgs e)
{
// Save position of cursor, because it like to dissapering.
int cursor = comboBox1.SelectionStart;
//Clearing items in dropDown
comboBox1.Items.Clear();
//Is something was searched before, cancel it!
while (backgroundWorker1.IsBusy)
{
if (!backgroundWorker1.CancellationPending)
{
backgroundWorker1.CancelAsync();
}
}
// And search new one
backgroundWorker1.RunWorkerAsync(comboBox1.Text);
// And bring back cursor to live
comboBox1.SelectionStart = cursor;
}
I hope that helped you

Hosting a UserControl inside a custom DataGridViewCell

I created a custom DataGridViewCell to show a specific UserControl when the user starts editing the cell. Basically the control contains a TextBox with a suggestion list easily handled by the code.
I got my code to resize the list correctly, and have it contain exactly what I want and where I want it. The problem I have now is that the control is not being drawn correctly on the screen, and the ListBox is probably beind drawn "inside" the row, and since it is much higher than the row, does not get shown on screen.
How can I make the control draw on top of the DataGridView?

You'll probably need to put the ListBox in a separate popup form. Good luck.
Alternatively, you can put the ListBox in the GridView's parent form, then call BringToTop to make sure it's on top of the grid view.

There's a msdn article, Build a Custom NumericUpDown Cell and Column for the DataGridView Control, that paints custom controls on datagridviews. The code sample provided there might help solve your problem.

I think you'll want to take a look at Faking alternative controls within a DataGridView control in Win Forms 2.0. It will look like the control is hosted within the DataGridView, but in actuality it is just positioned nicely over the cell. I am using this now for two DateTimePickers and one ComboBox with great success.
Sample code from link:
protected void dgCategory_CellClick(object sender, DataGridViewCellEventArgs e)
{
//set Date Picker to false when initially click on cell
if (dtPicker.Visible)
dtPicker.Visible = false;
if (e.ColumnIndex == 2)
{
//set date picker for category datagrid
dtPicker.Size = dgCategory.CurrentCell.Size;
dtPicker.Top = dgCategory.GetCellDisplayRectangle(e.ColumnIndex, e.RowIndex, true).Top;
dtPicker.Left = dgCategory.GetCellDisplayRectangle(e.ColumnIndex, e.RowIndex, true).Left;
if (!(object.Equals(Convert.ToString(dgCategory.CurrentCell.Value), "")))
dtPicker.Value = Convert.ToDateTime(dgCategory.CurrentCell.Value);
dtPicker.Visible = true;
}
}
private void dtPicker_ValueChanged(object sender, EventArgs e)
{
dgCategory.CurrentCell.Value = dtPicker.Value;
dtPicker.Visible = false;
}