I've set up a simple form. A ListBox takes values from a list in the 'business object' displaying the Name property and providing the Value property.
In additon the ListBox's SelectedItem property is bound to a property in the same business object.
Using the UI to select a value from the list correctly changes the objects property (checked when the button is clicked) and the correct value is available. So far so good.
However, if the ListBox's SelectedIndex property is changed in the code, then the UI correctly changes as expected but the business property does not change - it would appear to have missed the change event. This is true for both setting in the constructor and in the button event handler (see the code).
What have I missed or what am I doing incorrectly.
(I've only included the code I've written - not VS wizard generated stuff)
class Frequency
{
public String Name { get; set; }
public Int16 Value { get; set; }
public Frequency(String name, Int16 value)
{
Name = name;
Value = value;
}
}
class FrequencyList : System.ComponentModel.BindingList<Frequency>
{
}
class Model
{
public static FrequencyList FrequencyValues = new FrequencyList()
{
new Frequency("Slowest", 100),
new Frequency("Slow", 150),
new Frequency("Medium", 1000),
new Frequency("Fast", 5500),
new Frequency("Fastest", 10000)
};
public Frequency StartFrequency { get; set; }
public void DoStuff()
{
if (StartFrequency == null)
return;
Int16 freq = StartFrequency.Value;
}
}
public partial class Form1 : Form
{
private Model myModel = new Model();
public Form1()
{
InitializeComponent();
// Bind the list to a copy of the static model data
this.listBox1.DataSource = Model.FrequencyValues;
// Bind the control to the model value
this.listBox1.DataBindings.Add("SelectedItem", myModel, "StartFrequency");
// Select the start value
this.listBox1.SelectedIndex = 3;
}
private void button1_Click(object sender, EventArgs e)
{
Int16 f = (Int16)listBox1.SelectedValue;
this.myModel.DoStuff();
int new_index = listBox1.SelectedIndex + 1;
if (new_index >= listBox1.Items.Count)
new_index = 0;
listBox1.SelectedIndex = new_index;
}
}
You don't want the Click event, you want the SelectedIndexChanged event. This will trigger regardless of whether the user or the program instigates the change.
Related
I have a list of items that have a name, price and quantity value.
This list is stored in one form, and this form also had an edit button, so that when a user clicks on a row, they are able to edit this item inside another form that pops up.
I have my code working so that the item changes in the list, however it seems like the DataGridView just isn't updating when the list is changed.
When I edit an item, and add in a new row, it shows the changed values.
Here is my code for my first form:
private void EditButton_Click(object sender, EventArgs e)
{
EditForm editForm = new EditForm();
if (BasketGrid.RowCount > 0)
{
editForm.Show();
}
}
So this juts sets up the button so that it shows the other form.
"BasketGrid" is my DataGridView, that is also given a public initialization at the beginning of my code (Called dgv)
public void EditOkBut_Click(object sender, EventArgs e)
{
this.newName = editNameBox.Text;
decimal price;
int quant;
if (decimal.TryParse(editPriceBox.Text, out price))
{
this.newPrice = price;
}
else
{
MessageBox.Show("Incorrect format for price");
}
if(int.TryParse(editQuantBox.Text, out quant))
{
this.newQuantity = quant;
}
else
{
MessageBox.Show("Incorrect format for quantity");
}
foreach (OrderItem o in basketForm.GetList().ToList())
{
string listName = basketForm.getListName();
if (listName == o.ProductName)
{
o.ProductName = this.newName;
o.ProductPrice = this.newPrice;
o.ProductQuantity = this.newQuantity;
}
}
this.Close();
}
This is my "Edit Button" in my secondary form. This grabs my itemlist from my other form via a method, and compares the product name in of the orderitem in the list, and the listname that the user has selected from the row.
I'd created 'basketForm' as a new object of my other form, so I can access methods and stuff.
I've tried to use basketForm.dgv.Refresh(); but to no avail.
Any help is appreciated.
Cheers,
Daniel
You can use BindingSource and ShowDialog...
Example:
public partial class MainForm : Form
{
private BindingSource bindingSource = new BindingSource();
List<YourData> yourData = new List<YourData>();
public MainForm()
{
InitializeComponent();
bindingSource.DataSource = yourData;
dgv.DataSource = bindingSource;
}
}
Changes will be reflected to your grid like this...
private void EditButton_Click(object sender, EventArgs e)
{
EditForm editForm = new EditForm(yourData);
if (BasketGrid.RowCount > 0)
{
editForm.ShowDialog(this);
bindingSource.ResetBindings(true);
}
}
//Change your Data in EditForm whatever you want
public partial class EditForm : Form
{
List<YourData> yourData;
public EditForm(List<YourData> yourData)
{
InitializeComponent();
this.yourData = yourData;
}
}
You should implement INotifyPropertyChanged interface in the OrderItem class. This will update only one value in DataGridView, instead of updating the entire collection, which may be critical if the collection is very large and its binding may trigger actions, like validation, etc.
class OrderItem : INotifyPropertyChanged
{
private string name;
// other fields : price, quantity
public string Name
{
get { return name; }
set
{
if (value != name)
{
name = value;
NotifyPropertyChanged();
}
}
}
// other properties: Price, Quantity
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Also you have to use BindingList class instead of List. It supports two-way data-binding mechanism.
I am developing a Windows phone App and in my MainPage.xaml.cs file I have one private member that is being changed in the overrided method OnNavigateTo(). Although its value is changed, after that in the MainPage constructor its value resets to 0 (It's an int member). I guess that OnNavigateTo() method is being called BEFORE the constructor but if so I would have a nullReferenceException. What can cause that problem?
The OnNavigateTo() Function:
if (NavigationContext.QueryString.ContainsKey("leftDuration"))
{
//Get the selected value from IntroductionPage as a string
var leftRecievedInformation = NavigationContext.QueryString["leftDuration"];
//Convert the string to an enum object
var firstRunLeftChosenDuration = (LensLifetime)Enum.Parse(typeof(LensLifetime), leftRecievedInformation);
//Set the leftDuration value to the model object
_firstRunLeftDuration = getDurationAsNumber(firstRunLeftChosenDuration);
MessageBox.Show(_firstRunLeftDuration + "");
model.Left.LifeTime = _firstRunLeftDuration;
}
My problematic member is the _firstRunLeftDuration value. Although, as you can see, i set the model.Left.LifeTime value, in the MainPage.xaml I still get the default 0 value... It' like completely ignoring this line of code.. I know the code is not particularly clear but I don't think its beneficial to add extra lines of useless code.
Here's the MainPage.xaml.cs file:
public partial class MainPage : PhoneApplicationPage
{
public ContactLensesModel model;
private int _firstRunLeftDuration, _firstRunRightDuration; //Members used for the initialization of the app
public int FirstRunLeftDuration
{
get
{
return _firstRunLeftDuration;
}
set
{
_firstRunLeftDuration = value;
}
}
public int FirstRunRightDuration
{
get
{
return _firstRunRightDuration;
}
set
{
_firstRunRightDuration = value;
}
}
public ContactLensesModel Model
{
get
{
return model;
}
set
{
model = value;
}
}
// Constructor
public MainPage()
{
InitializeComponent();
// Sample code to localize the ApplicationBar
BuildLocalizedApplicationBar();
//Should check if the user starts the app for the first time....
//Create a new model
Model = new ContactLensesModel();
Model.setLeftNewStartingDate();
Model.setRightNewStartingDate();
//Should load the already saved model if the user in not entering for the first time...
//....
//....
loadModel();
//Connect the data Context
leftLensDaysRemaining.DataContext = Model.Left;
rightLensDaysRemaining.DataContext = Model.Right;
}
private int getDurationAsNumber(LensLifetime duration)
{
if (duration.Equals(LensLifetime.Day))
return 1;
else if (duration.Equals(LensLifetime.Two_Weeks))
return 14;
else
return DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month);
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
//Get the arguments as strings and convert them to an enum, is true only when the user enters app for the first time.
if (NavigationContext.QueryString.ContainsKey("leftDuration"))
{
//Get the selected value from IntroductionPage as a string
var leftRecievedInformation = NavigationContext.QueryString["leftDuration"];
//Convert the string to an enum object
var firstRunLeftChosenDuration = (LensLifetime)Enum.Parse(typeof(LensLifetime), leftRecievedInformation);
//Set the leftDuration value to the model object
FirstRunLeftDuration = getDurationAsNumber(firstRunLeftChosenDuration);
Model.Left.LifeTime = FirstRunLeftDuration;
}
if (NavigationContext.QueryString.ContainsKey("rightDuration"))
{
//Get the selected value from IntroductionPage as a string
var rightRecievedInformation = NavigationContext.QueryString["rightDuration"];
//Convert the string to an enum object
var firstRunRightChosenDuration = (LensLifetime)Enum.Parse(typeof(LensLifetime), rightRecievedInformation);
//Set the leftDuration value to the model object
_firstRunRightDuration = getDurationAsNumber(firstRunRightChosenDuration);
Model.Right.LifeTime = _firstRunRightDuration;
}
}
/// <summary>
/// Loads the model from the isolated Storage
/// </summary>
private void loadModel()
{
//Load the model...
}
private void BuildLocalizedApplicationBar()
{
// Set the page's ApplicationBar to a new instance of ApplicationBar.
ApplicationBar = new ApplicationBar();
// Create a new button and set the text value to the localized string from AppResources.
ApplicationBarIconButton appBarSettingsButton = new ApplicationBarIconButton(new Uri("/Assets/Icons/settingsIcon4.png", UriKind.Relative));
appBarSettingsButton.Text = AppResources.AppBarSettingsButtonText;
appBarSettingsButton.Click += appBarButton_Click;
ApplicationBar.Buttons.Add(appBarSettingsButton);
// Create a new menu item with the localized string from AppResources.
//ApplicationBarMenuItem appBarMenuItem = new ApplicationBarMenuItem(AppResources.AppBarMenuItemText);
//ApplicationBar.MenuItems.Add(appBarMenuItem);
}
void appBarButton_Click(object sender, EventArgs e)
{
NavigationService.Navigate(new Uri("/SettingsPage.xaml", UriKind.RelativeOrAbsolute));
}
private void leftButtonChange_Click(object sender, RoutedEventArgs e)
{
model.setLeftNewStartingDate();
}
private void rightChangeButton_Click(object sender, RoutedEventArgs e)
{
model.setRightNewStartingDate();
}
}
}
The OnNavigatedTo method cannot be called before the constructor. The constructor is always executed first. I think your model.Left.LifeTime doesn't raise a PropertyChanged event. Hence, your View won't know you are giving it a value. Therefore it will show the default value of model.Left.Lifetime which is probably 0.
On the other hand, it's hard to tell without seeing the rest of your code.
I am trying to set up a multi-language application, so when the user changes the display language all the texts in all the open windows change automatically.
I am having issues through with binding combo-box control. The binding needs to be done in code-behind as I have dynamic content coming from a database, and sometimes I even have to create additional combo-boxes at runtime.
Also I do not want to keep the translations in the database because I do not want to query the database every time a user is changing the display language.
What I did until now:
in xaml:
<ComboBox x:Name="cmb"/>
and in C#:
public class MyCmbItem
{
public int Index { get; set; }
public string Text { get; set; }
}
private ObservableCollection<MyCmbItem> LoadText()
{
ObservableCollection<MyCmbItem> _result = new ObservableCollection<MyCmbItem>();
foreach (var _item in _list)
{
//the list is coming from a database read
_result.Add(new MyCmbItem { Index = _item.Value, Text = _res_man_global.GetString(_item.KeyText, _culture) });
}
return _result;
}
public ObservableCollection<MyCmbItem> MyTexts
{
get { return LoadText(); }
set {} //I do not have to add/remove items at runtime so for now I leave this empty
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
...
LoadList(); //this adds values in _list
cmb.ItemsSource = MyTexts; //this populates the combo-box
Here I got stuck and I do not know how to determine the combo-box to refresh the displayed texts. The method must achieve that if I have several windows opened each containing a random number of combo-boxes, when I change the current language all the combo-boxes in all the windows will refresh the displayed list, without affecting other values inside (like the selected item). Does anybody know how this can be done?
Many thanks.
For your xaml UI, the INotifyPropertyChanged interface indicates updates of the viewmodel. You can extend your class like this:
public class MyCmbItem : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(string APropertyName)
{
var property_changed = PropertyChanged;
if (property_changed != null)
{
property_changed(this, new PropertyChangedEventArgs(APropertyName));
}
}
private string _Text;
private string _KeyText;
public int Index { get; set; }
public string Text
{
get { return _Text;}
set {
if (_Text != value)
{
_Text = value;
NotifyPropertyChanged("Text");
}
}
}
public MyCmbItem(string key_text, int index)
{
Index = index;
_KeyText = key_text;
RefreshText();
_res_man_global.LanguageChanged += () => RefreshText();
}
public void RefreshText()
{
Text = _res_man_global.GetString(_KeyText, _culture);
}
}
Your view can simply bind to the Text-property as following:
<DataTemplate DataType="{x:Type local:MyCmbItem}">
<TextBlock Text="{Binding Path=Text}"/>
</DataTemplate>
Note: I assumed that your language class is global and has some kind of language-changed notification event.
I have the following ViewModel and in my code link this to an items control. However when I use a line such as:
onOffSchedule.dc.schedules[0].days[0].data[0] = 9;
it only updates the UI sometimes?? And when it does it updates the data all wrong. Instead of assign the first schedule, the first day, and first time slot to 9. It updates the first schedule (for all days??) for the first time slot.
So I am trying to figure out why it updates every index in the days array instead of just the first one.
Thanks in advance!
public class ScheduleVM
{
public ObservableCollection<Schedule> schedules { get; set; }
private static ScheduleVM viewModel = null;
public static ScheduleVM getInstance()
{
if (viewModel == null)
viewModel = new ScheduleVM();
return viewModel;
}
private ScheduleVM()
{
schedules = new ObservableCollection<Schedule>();
for (byte i = 0; i < 32; i++)
schedules.Add(new Schedule());
}
}
public class Schedule
{
public ObservableCollection<Day> days { get; set; }
public Schedule()
{
days = new ObservableCollection<Day>();
int[] values = new int[96];
for (byte i = 0; i < 96; i++)
values[i] = 3;
for (byte i = 0; i < 8; i++)
days.Add(new Day() { data = values });
}
}
public class Day : BaseVM
{
private int[] _data;
public int[] data
{
get
{
return _data;
}
set
{
_data = value;
OnPropertyChanged("data");
}
}
}
Below is the view that goes along with this code. It is a user control that I create inside another window (and inside that window the user control is called 'onOffSchedule'.
public ScheduleVM dc { get; private set; }
public Schedule()
{
InitializeComponent();
dc = ScheduleVM.getInstance();
this.DataContext = dc;
schedule.ItemsSource = dc.schedules[0].days;
}
onOffSchedule.dc.schedules[0].days[0].data[0] = 9;
That line will not trigger an update under normal circumstances. What you're doing is just setting an integer in an integer array:
public int[] data { ... }
You put the OnPropertyChanged call in there for when the entire array changes. But when you just set one of the values, WPF doesn't know that occurred.
You have the right idea by using the ObservableCollection<Day> on your other class. You need to do something similar in your Day class for the data property.
You're updating an element within the data array. That array does not fire off property changed notifications, so there's no way that the View knows to update itself. Make your data an ObservableCollection and see if it helps.
I can't understand the following 2 issues given this code. I mapped a combobox to a custom object and I want each time that the selected value change on the combobox, the custom object changes too.
public partial class MainForm : Form
{
private Person _person;
public MainForm()
{
InitializeComponent();
_person = new Person();
//Populating the combox, we have this.comboBoxCities.DataSource = this.cityBindingSource;
cityBindingSource.Add(new City("London"));
cityBindingSource.Add(new City("Paris"));
_person.BirthCity = new City("Roma");
cityBindingSource.Add(_person.BirthCity);
cityBindingSource.Add(new City("Madrid"));
//Doing the binding
comboBoxCities.DataBindings.Add("SelectedItem", _person, "BirthCity");
}
private void buttonDisplay_Click(object sender, EventArgs e)
{
MessageBox.Show("BirthCity=" + _person.BirthCity.Name);
}
private int i = 0;
private void buttonAddCity_Click(object sender, EventArgs e)
{
City city = new City("City n°" + i++);
cityBindingSource.Add(city);
comboBoxCities.SelectedItem = city;
}
}
public class Person
{
private City _birthCity;
public City BirthCity
{
get { return _birthCity; }
set
{
Console.WriteLine("Setting birthcity : " + value.Name);
_birthCity = value;
}
}
}
public class City
{
public string Name { get; set; }
public City(string name) { Name = name; }
public override string ToString() { return Name; }
}
1 - why when I manually select twice in a row (or more) different value on the combobox, I got only one call to BirthCity.Set witht he last selected value (and the call seems firing only when the combobox lost the focus) ?
2 - why when I click buttonAddCity and then buttonDisplay, the diplayed city is not the one selected (not the one displayed in the comobox )
why when I manually select twice in a row (or more) different value on the combobox, I got only one call to BirthCity.Set witht he last selected value (and the call seems firing only when the combobox lost the focus) ?
That's how Data Binding works, data is moved from the control to the property when validation occurs, and validation occurs when the control loses focus.
why when I click buttonAddCity and then buttonDisplay, the diplayed city is not the one selected (not the one displayed in the comobox )
I don't know. I created a simple form (Visual C# Express 2008 using .Net 3.5 SP1) and pasted your code pretty much verbatim, and it works as expected: it shows the new city in the combo box.
If you add comboBoxCities.Focus (); to the end of buttonAddCity_Click (), you'll make sure the new city gets pushed into _person.BirthCity earlier rather than on ValidateChildren ().