Develop Reference

Databinding to TextBox - setting Text property in code doesn't update model

I am working on some data collection forms in WinForms/C#. When the form loads, I am looping through a configuration and adding a new Binding to each of the TextBox controls; mapping the Text property of each TextBox control to specific string property on my POCO object.
public void BindTextBoxControls(dynamic entity, List<TextBoxConfig> textBoxConfig)
{
foreach (var config in textBoxConfig)
config.Control.DataBindings.Add(new Binding("Text", entity, config.PropertyName));
}
Everything has been working as expected, new records properly saving new values entered into the corresponding TextBox controls, TextBoxes populating with the correct values when reopened a previously entered records with the form, and updates to values in TextBoxes of previously entered records are getting the updated values set on the underlying POCO.
However, I started to layer in some business rules onto the form specifically to gray out/disable and clear out previously entered values in the TextBox based on other user input/activity on the form - things are not working as expected.
In a contrived example; a rule like if a Checkbox_1 is checked then TextBox #5 should not be valued (clear out any previously entered value and disable it from input). On my Checkbox_1 event handler for CheckedChanged, I specifically check if the Checkbox_1 is checked and if so, set TextBox_1.Text == null and TextBox_1.Enabled = false. This works as expected and on the form, I see any previously entered value cleared from the TextBox_1 and it becomes enabled.
private void chkCheckBox1_CheckedChanged(object sender, EventArgs e)
{
if(!chkCheckBox1.Checked)
{
txtBox5.Text = string.Empty;
}
}
However, when I debug and break on the save and inspect the underlying POCO's property that the underlying control is bound to after the method is called; the old value still persists on the object's property which the text box is bound to, despite the textbox having not value appearing on the form. When I reopen the form for that record, the old cleared out value is re-populated in the disabled TextBox. However, manually clearing out the value in the same TextBox or updating a value and inspecting the object shows the updated value after those operations are performed.
It seems like changing the Text value of a TextBox control (e.g. the Text property of a TextBox) in code maybe somehow be "bypassing" the DataBinding? I'm actually seeing the same/similar behavior when applying similar rules to "uncheck" TextBoxes programmatically within event handler methods - the CheckBox controls are also using DataBinding to boolean properties on the POCO.

When you setup databinding by this overload: Binding(String, Object, String), then the value of DataSourceUpdateMode will be OnValidation, which means when you modify the value of control's property using code or through UI, the binding will push the new value to data source only after Validating event happens for the control.
To fix the problem, use either of the following options:
Use another overload and set the DataSourceUpdateMode to OnProperetyChanged
OR, after setting the Value of the TextBox.Text call ValidateChildren method of the form.
Example - Set the DataSourceUpdateMode to OnProperetyChanged
public class Person
{
public string Name { get; set; }
public string LegalCode { get; set; }
public bool IsRealPerson { get; set; }
}
Person person;
private void Form1_Load(object sender, EventArgs e)
{
person = new Person() {
Name = "My Company", LegalCode = "1234567890", IsRealPerson = false };
NameTextBox.DataBindings.Add(nameof(TextBox.Text), person,
nameof(Person.Name), true, DataSourceUpdateMode.OnPropertyChanged);
LegalCodeTextBox.DataBindings.Add(nameof(TextBox.Text), person,
nameof(Person.LegalCode), true, DataSourceUpdateMode.OnPropertyChanged);
IsRealPersonCheckBox.DataBindings.Add(nameof(CheckBox.Checked), person,
nameof(Person.IsRealPerson), true, DataSourceUpdateMode.OnPropertyChanged);
IsRealPersonCheckBox.CheckedChanged += (obj, args) =>
{
if (IsRealPersonCheckBox.Checked)
{
LegalCodeTextBox.Text = null;
LegalCodeTextBox.Enabled = false;
}
};
}
Note - You can put the logic inside the model
Another solution (Which needs more effort and more changes in your code) is implementing INotifyPropertyChanged in your model class. Then when PropertyChanged event raises for your boolean property, you can check if it's false then you can set the string property to null.
In this approach you don't need to handle UI events. Also right after updating the model property, the UI will be updated; in fact implementing INotifyPropertyChanged enables two-way databinding for your model class.

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.

Implement a c# windows forms Autocomplete textbox with multiple suggested columns

I am attempting to implement a Windows Forms control in C# that resembles a textbox. When the user types 3 or more characters, a search will be performed against a datasource. There will be multiple fields returned (see the class structure below as one possible definition).
public class MyStructure
{
public int Value1 { get; set; }
public string Value2 { get; set; }
public string Value3 {get; set; }
}
My requirements are to display an autocomplete list containing multiple columns (Note: this can be a string that contains padded fields from the list that are concatenated together). When the user either types all characters, hits the down arrow to select an item, or hits the enter key the value in the textbox will take the ValueMember of the list (where the DisplayMember of the list would be the whole data source). Every keystroke that the user enters that is not an up or down arrow or the enter key will perform another search and refresh the list.
I have seen how to implement a textbox with a single column in an auto-suggest, but cannot find a relatively "simple" example of how to do this for multiple columns. Should the control be a textbox or a combobox that is somehow styled to resemble a textbox (if this is possible) or a user control?
Should the event to monitor keystrokes be the TextEntered or the KeyPress event? Can I reset the AutoCompleteStringCollection without having the contents entered affected (I keep losing my input or my place in the input in any attempts)?
Can anyone provide examples of how to do this in framework 4.0 or above or point me to an example?
EDIT 1:
After much searching, I have found that essentially I need to implement a ContextMenuStrip on the TextBox (anything else and other controls below the user control will be overlapped). My problem is that I cannot determine how to handle the Key press events such as Tab and Enter. In addition, I need to handle if the user continues typing (in this event, I want to switch focus back to the textbox and add the key). Below is my code:
private void textBox1_TextChanged(object sender, EventArgs e)
{
ContextMenuStrip menuStrip;
string szMenuItem = string.Empty;
// This would actually be a call to a web service
List<MStarDeal> deals = DealInfo.Where(i => i.Value1.StartsWith(textBox1.Text.ToUpper()) || i.Value2.StartsWith(textBox1.Text.ToUpper()) || i.Value3.StartsWith(textBox1.Text.ToUpper()))
.Select(i => i).ToList();
if (textBox1.Text.Length >= 3 && !bSelected)
{
menuStrip = new System.Windows.Forms.ContextMenuStrip();
foreach (MStarDeal item in deals)
{
szMenuItem = item.Value1.PadRight(15) + item.Value2.PadRight(20) + item.Value3.PadRight(80);
ToolStripItem tsItem = new ToolStripMenuItem();
tsItem.Text = szMenuItem;
tsItem.Name = item.Value1;
tsItem.MouseUp += tsItem_MouseUp;
menuStrip.Items.Add(tsItem);
}
textBox1.ContextMenuStrip = menuStrip;
textBox1.ContextMenuStrip.Show(textBox1, new Point(0, 20));
}
else if (bSelected)
{
bSelected = false;
}
}
void tsItem_MouseUp(object sender, EventArgs e)
{
bSelected = true;
textBox1.Text = ((ToolStripMenuItem)sender).Name;
}
Thanks,
Lee

I think I understand your question. How about using the TextChanged() event instead of KeyPress? As far as the columns, a flowLayoutPanel will render columns if you set it up to flow in the right direction and make its size appropriate to the width of the two columns combined.

Moving data between two user controls in WinForm Application

As a course project i'm building a form in c# which contains two user controls.
The first user control has a checkedlistbox and the second control has also a checkedlistbox when the first control checkedlistbox will contain list of people (male/female) and the second user control the checkedlistbox will have two options: male, female and when I click a button on the first control which says: "update friends" it's suppose to go to the second control and check if we selected male or female and according to that to update the checkedlistbox in the first user control with friends by gender type by what was selected on the second control.
Basically I want to raise an event every time the button on the first control selected then to get the data from the second control to the first control.
Is it possible to do so between two controls who are inside a form and are different controls?
Any help will be appriciated.
Thanks.

To do this "correctly," you would want to use something like the MVC architecture. It's definitely a lot more work initially to understand and implement but is very useful to know if you plan on doing any serious UI application development. Even if you don't go all the way with it, the concepts are useful to help design even "quick and dirty" applications.
Define your data model without thinking in terms of the UI, e.g.:
internal enum Gender
{
Male,
Female
}
internal class Person
{
public Gender Gender { get; set; }
public string Name { get; set; }
}
// . . .
// Populate the list of people
List<Person> allPeople = new List<Person>();
allPeople.Add(new Person() { Gender = Gender.Male, Name = "Xxx Yyy" });
allPeople.Add(new Person() { Gender = Gender.Female, Name = "Www Zzz" });
// . . .
For the view portion, you would typically use data binding on the UI controls so that the controls will automically reflect changes to the underlying data. However, this can get difficult especially if you are not using a database-like model (e.g. System.Data.DataSet). You may opt to "manually" update the data in the controls which might be fine in a small app.
The controller is the portion that uses the UI events and makes changes to the model, which may then be reflected as changes in the view.
internal class Controller
{
private Gender selectedGender;
private List<Person> allPeople;
private List<Person> friends;
public Controller(IEnumerable<Person> allPeople)
{
this.allPeople = new List<Person>(allPeople);
this.friends = new List<Person>();
}
public void BindData(/* control here */)
{
// Code would go here to set up the data binding between
// the friends list and the list box control
}
// Event subscriber for CheckedListBox.SelectedIndexChanged
public void OnGenderSelected(object sender, EventArgs e)
{
CheckedListBox listBox = (CheckedListBox)sender;
this.selectedGender = /* get selected gender from list box here */;
}
// Event subscriber for Button.Click
public void OnUpdateFriends(object sender, EventArgs e)
{
this.friends.AddRange(
from p in this.allPeople
where p.Gender == this.selectedGender
select p);
// If you use data binding, you would need to ensure a
// data update event is raised to inform the control
// that it needs to update its view.
}
}
// . . .
// On initialization, you'll need to set up the event handlers, etc.
updateFriendsButton.Click += controller.OnUpdateFriends;
genderCheckedListBox.SelectedIndexChanged += controller.OnGenderSelected;
controller.BindData(friendsListBox);
// . . .
Basically, I recommend not having controls talk directly, but rather through a controller-like class as above which has knowledge of the data model and the other controls in the view.

Of course it's possible: you need to make the link between the 2 controls in the form.
Just declare an event 'ButtonClicked' in control #1
Then make a public method 'PerformsClick' on the control #2
And in the form, in the constructor, after the call to InitializeComponent, link the event from the control #1 to the method to the control #2:
control1.ButtonClicked += delegate(sender, e) {
control2.PerformsClick();
};
(I type on the fly to give you an idea, it'll surely not compile)
If you want to pass any data, just add parameters in the PerformsClick method.