Develop Reference

Int field in Winform does not update null values in SQL Server database using C#

In my Winforms C# application, I have fields with Int data type and they are set to accept null values in SQL Server database (allow nulls).
In the forms I have some textboxes which are bound to those int data type fields. If I don't enter anything while creating a new record, it accepts. If I enter a number in the textbox, it also accepts it, and then if I delete it, it doesn’t accept it anymore and even doesn't allow me to move to the next field.
If I set its value as null or "" through code, it simply ignores and does not even update changes which I made in other non int text fields.
I am using following method to update.
this.Validate();
this.itemsbindingSource.EndEdit();
this.tableAdapterManager.UpdateAll(this.sBSDBDataSet);
What can I do for the textbox to accept null values?
I have tried following.
IDTextBox.Text = "";
IDTextBox.Text = null;

I have tried following with the help of above solutions (specially Mr. Ivan) and this is how it worked out.
To clear the int field on the form:
IDTextBox.Text = String.Empty;
Then on Designer.cs file of the form, as suggested by Mr. Ivan, I searched for 'IDtextbox.DataBindings.Add' and replaced
this.IDTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.itemsbindingSource, "PictureID", true));
with
this.IDTextBox.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.itemsbindingSource, "PictureID", true, System.Windows.Forms.DataSourceUpdateMode.OnValidation, ""));
It took me a whole day to search and finally I posted my problem here, and it got solved in 1 hour.

This seems to be one of the WF data binding bugs. I can't say what exactly is causing it, but in order to make it work one should set Binding.NullValue property to "" (empty string, the default is null).
I couldn't find a way to do that in the designer, and also it would be quite annoying to locate all text boxes needed. So I would suggest you the following quick-and-dirty approach. Create a helper method like this:
public static class ControlExtensions
{
public static void FixTextBoxBindings(this Control control)
{
if (control is TextBox)
{
foreach (Binding binding in control.DataBindings)
if (binding.NullValue == null) binding.NullValue = "";
}
foreach (Control child in control.Controls)
child.FixTextBoxBindings();
}
}
and then simply include the following in your form Load event:
this.FixTextBoxBindings();

TextBox dont accept null value.
You can check if it null and set String.Empty;
If(dbValue == null)
{
IDTextBox.Text = String.Empty;
}
else
{
// here set value to your textbox
}

ObjectListView editing doesn't work

I'm trying to create a simple listbox with ObjectListView (WinForm, C#). The goal is to have a single value (a double) and a check box.
I want to be able to edit the double value by Single Click, so here are the relevant lines of code from my MyWindow.Designer.cs file (i've left out the default values for efficiency):
this.olvDepths = new BrightIdeasSoftware.ObjectListView();
this.olvColumn1 = ((BrightIdeasSoftware.OLVColumn)(new BrightIdeasSoftware.OLVColumn()));
...
this.olvDepths.CellEditActivation = BrightIdeasSoftware.ObjectListView.CellEditActivateMode.SingleClick;
this.olvDepths.CheckBoxes = true;
this.olvDepths.CheckedAspectName = "IsDefault";
this.olvDepths.FullRowSelect = true;
//
// olvColumn1
//
this.olvColumn1.AspectName = "Depth";
this.olvColumn1.Text = "";
this.olvColumn1.IsEditable = true;
I then create a list of my class (ShieldingEntry) and use the olvDepths.SetObjects() with the list. My ShieldingEntry class looks like this:
public class ShieldingEntry
{
public double Depth { get; set; }
public bool IsDefault { get; set; }
}
However, when I click the field, it doesn't go into edit mode. I've also tried the DoubleClick, SingleClickAlways, and F2Only modes and they don't work either.
The Checkbox works fine.
************** I have additional information *********************
I've pulled and build the ObjectListView source, so I could step through it.
I put a breakpoint in the OLV StartCellEdit method and it gets called and appears to setup and select the control appropriately. It just never appears...
As I noted in the comments on the answer below, I've got this control on a tabbed dialog, and if I switch to another tab, then back, the control works fine.
What am I missing?

I've used ObjectListView before, and here is what I had to do:
Handle the CellEditStarting event. This event is raised when the cell goes into edit mode. Since OLV doesn't really have built-in editors, you have to make your own. Then handle the CellEditFinishing event to validate the data before putting it back into your model.
So first, handling the CellEditStarting event:
private void objlv_CellEditStarting(object sender, CellEditEventArgs e)
{
//e.Column.AspectName gives the model column name of the editing column
if (e.Column.AspectName == "DoubleValue")
{
NumericUpDown nud = new NumericUpDown();
nud.MinValue = 0.0;
nud.MaxValue = 1000.0;
nud.Value = (double)e.Value;
e.Control = nud;
}
}
This creates your editing control. If you want to make sure the size is right, you can set the size of the control (in this case a NumericUpDown) to the cell bounds using e.CellBounds from the event object.
This will show the editor when you click in the cell. Then you can handle the editor finished event to validate the data:
private void objlv_CellEditFinishing(object sender, CellEditEventArgs e)
{
if (e.Column.AspectName == "DoubleValue")
{
//Here you can verify data, if the data is wrong, call
if ((double)e.NewValue > 10000.0)
e.Cancel = true;
}
}
I don't think handling it is required, but its good practice to validate data from the user.
The editing control in the CellEditStarting event can be any control, even a user defined one. I've used a lot of user defined controls (like textboxes with browse buttons) in the cell editor.
[Edit]
I uploaded an example here dropbox link that seems to work. Might not be in the exact view as needed, but seems to do the job.

For anyone else with this problem. I had it specifically when trying to edit a 'null' value in a decimal? on the OLV on a tab page. Solution for me was to set UseCustomSelectionColors to 'False'. I didn't look elsewhere to see if it was reported as a bug. Seems like a bug.

Using a ComboBox, UserControl and some forms to change language (for entire project)

Before I begin, I have researched and can't seem to find anything. Note I am very new to UserControl so this might be why it's proven difficult.
I have a combobox in Form1 which when selected allows the user to change between a choice of 21 languages. I have created a UserControl that contains labels, buttons and checkboxes - adds to a form called Print.
If a user selected French, how would I then implement the UserControl to change language for ALL forms in my project?
UserControl:
I have used a get and set method here for a button. When the language is changed in Form1, I want this button (all elements really) to change.
using System.Windows.Forms;
namespace Print
{
public partial class UserControl1 : UserControl
{
public UserControl1()
{
InitializeComponent();
}
public string LabelPreview
{
get
{
return Button_Preview.Text;
}
set
{
Button_Preview.Text = value;
}
}
}
}
Form1:
If string value English is selected in the combobox, call a method - here is where I would like to change language for other forms.
private void ComboBoxLang_SelectedIndexChanged(object sender, EventArgs e)
{
string selectedItem = this.comboBoxLang.GetItemText(this.comboBoxLang.SelectedItem);
if (selectedItem == Language.English)
{
ToEnglish();
}
}
private void ToEnglish()
{
// Cannot actually implement the UserControl, It can't find the method above.
// When I've tried to implement UserControl in Print, it can't seem to find it either.
// I've tried:
// Print.UserControl1.(_LabelPreview doesn't show_);
// ^ It might be the completely wrong thing to do so excuse me.
}
I'm so confused... Do I program in Print (where the UserControl is added) or/and Form1?! I don't want the design to appear in Form1, but just want to let the other forms know what language has been selected.
Note: I have been using Unicode when translating*

How to trigger application-wide language change I described here on your other question Everytime ComboBox is changed (using SelectedIndexChanged) display message in other forms, if opened, of new value
Now, to set controls... One way of doing it is to create Database of phrases with StringId in one table and the StringId, LanguageId, StringValue in another. You would create StringManager object, which will have method GetLanguageSpecificString(stringId, languageId). When language change is triggered, your controls will call GetLanguageSpecificString fro each label you display, etc.
So your data will be like
Table DisplayLanguage
LanguageId Int
LanguageName nvarchar
LanguageCulture varchar
//1, English, us-En
//2, French, fr-Ca
Table DisplayString
StringId Int
//1
//2
//3
Table DisplayStringValue
DisplayStringValueId int
StringId int
LanguageId int
StringValue nvarchar
//1, 1, 1, Person Name
//2, 1, 2, Nome de Persona(or whateever)
Create cache using
"Select * from DisplayStringValue where LanguageId = 1"
And then use Linq or something to select for each control its data from cache because you don't want to hit DB with these for each control
"Select StringValue from DisplayStringValue where StringId = 1 and LanguageId = 1"
Now, combine my other answer with this and you will see that if in your form you have
LanguageChangeObserver.LanguageChanged += MyObserverHandler;
private void MyObserverHandler(languageId)
{
_formLanguage = languageId;
// set your controls
lblFirstName.Text = GetLanguageSpecificString(5, languageId);
lblLastName.Text = GetLanguageSpecificString(6, languageId);
// loop through userControls and pass to them language id
}
It would be good idea if your user controls would derive from the single base class that you create and which has already SetNewLanguage Method, so you could do
foreach (var c in form.controls)
{
MyControlBase currControl = c as MyControlBase;
if (currControl != null) currControl.SetNewLanguage(languageId);
}

So I've come up with a solution that works for me! I've copied across from the Printer.cs form where I have used a parameter to represent the language chosen, initiated strTextBox to equal label1 and included an if statement to see if the language is English (also working with UserControl to get the value of labels etc.).
Printer
public Printer(string strTextBox)
{
InitializeComponent();
label1.Text = strTextBox;
if (label1.Text == Language.English)
{
UserControl111.Label_Option_Multi = "Please select an option:"; //Simple test
}
}
Form1
private void Print_Click(object sender, EventArgs e)
{
string selectedItem = this.ComboBox_Lang.GetItemText(this.ComboBox_Lang.SelectedItem);
Printer p = new Printer(selectedItem);
p.Show();
}
UserControl
public string Label_Option_Multi
{
get
{
return Label_Option.Text;
}
set
{
Label_Option.Text = value;
}
}
As a result, if I select English in Form1.s then open up Printer.cs, the label displays English and translates accordingly.

You have to do it same way as for any other control. Imagine you have created your TextBox and now want all your textboxes in the project on each form to do something.
Obviously, you have to get a list of such controls somehow. One approach is to use Application.Forms to iterate through everything. Other is to register your control (add to a list) every time when it's created or shown or what_you_need and de-register (remove from a list) otherwise.

C# custom control property: unable to set DefaultValue field

I am trying to set a custom C# control property.
Here's my code:
/* Cancel's button text */
[Category("ComboTouch"),
Description("Text to display in cancel button"),
DefaultValue("Cancel")]
public String ct_cancelButtonText { get; set; }
I can get the property when I use the customized control in other projects (as you can see in the image); but configuration parameter DefaultValue seems not to work.
Could anybody help me? Thank you very much.
01/10/13 Update. Thank you very much for your answers, you solved my problem.
I would like to share how I finally could set the default value automatically:
private String m_cancelButtonText="Cancel";
/* Cancel's button text */
[Category("ComboTouch"),
Description("Text to display in cancel button"),
DefaultValue("Cancel")]
public String ct_cancelButtonText
{
get
{
return m_cancelButtonText;
}
set
{
m_cancelButtonText = value;
}
}
One curiosity: please check the format of 'Cancel' text. If I set DefaultValue type; it looks like normal text. But if I don't, it looks like bold text. I know it's silly; but I would like to know why it is that way. Thank you.

As noted in documentation:
A DefaultValueAttribute will not cause a member to be automatically initialized with the attribute's value. You must set the initial value in your code.

Correct way to implement web part personalisation for listboxes

Trying to work out this whole web part personalisation, and trying to implement it for a list box.
Well the end result will be two list boxes, with interchangeable values (ie, a value will only exist in one of the listboxes)
But I can't maintain the datasource for it. So maybe I'm going about it wrong?
This is what I have for a test H2 tag on the page
[Personalizable(PersonalizationScope.User)]
public string LabelText {
get { return h2Test.InnerText; }
set { h2Test.InnerText = value; }
}
And it works fine, if I have a textbox and use it to change the value of LabelText, then when I close the browser it automagically persists the change.
So I thought, ok, then maybe the same will work with a list box
[Personalizable(PersonalizationScope.User)]
public DomainList Domains {
get { return (DomainList)lstBxDomains.DataSource; }
set {
lstBxDomains.DataSource = value;
lstBxDomains.DataBind();
}
}
Where DomainList is just a class which extends List, and Domain is just a three field class, int, string, string.
But it doesn't, so is this too complicated for the webpart personalisation automagican, or have i just implement it wrongly (Which is more than likely)
This is my event handler to remove the items from the list:
protected void btnRemDomain_Click(object sender, EventArgs e) {
if (IsPostBack && lstBxDomains.SelectedIndex > -1) {
for (int i = 0; i < lstBxDomains.Items.Count; i++) {
if (lstBxDomains.Items[i].Selected) {
Domains.Remove(Domains.Find(d => d.ID.ToString() == lstBxDomains.Items[i].Value));
}
}
Domains = Domains;
}
}
The Domains=Domains; line is in there to see if explicitly setting the value made a difference (as Removing doesn't acutally reset the value of the field), but it doesn't. I've also tried creating a new local DomainList setting it to the global one, and then doing the remove/find on it, and then setting the local one to the global. But not working either.

I have managed to resolve this by using WebPart.SetPersonalizationDirty(this); in the set accessor of Domains, but would someone mind confirming if this is an appropriate way to do it?