Develop Reference

Binding a List<string> to a ComboBox for display in a view (MVVM)

I am attempting to bind a list to a combobox. I want to display this list of options within the Combobox itself. (Later to allow the user to select an item 'SelectedItem', I'll cross that bridge when I get there)
MyCode.cs
// List of values for 'Type' dropdown
private static readonly List<string> MarkerTypeList = new List<string>(new string[]
{
"Analog",
"Digital"
});
// Binding for viewing list in window
public List<string> TypeOptions
{
get { return MarkerTypeList; }
}
MyCode.xaml
<ComboBox x:Name="myCombobox" HorizontalAlignment="Left" Margin="125,26,0,0" VerticalAlignment="Top" Width="70" Height="23" SelectedItem="" ItemsSource="{Binding TypeOptions}" />

The solution boiled down to changing this:
ItemsSource="{Binding TypeOptions}"
to this:
ItemsSource="{Binding Marker.TypeOptions}"
Thanks for the input, sorry you didnt have a whole lot to go on.

If you bind you should have your INotifyPropertyChanged interface added to your class which is the actual ViewModel for your ComboBox.
So - 1. Add the Interface to the class. 2. Create RaisePropertyChanged function. 3. Call the function through the setter of the property. This will push the updated value of the property through the binding and you will see the combobox populated.

How to show values in Picker occupying MVVM with Xamarin

I want to Bindar an ObservableCollection of the Manufacturer Object and show its Name property in a Picker occupying the MVVM pattern in Xamarin, but I'm not getting results (Blank Picker)
This Picker is displayed in the View FiltersSisquimView.xaml as follows
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
BindingContext="{Binding Main, Source={StaticResource Locator}}"
x:Class="AppValora.Views.Sisquim.FiltrosSisquimView"
Title="SISQUIM®">
<StackLayout
Orientation="Vertical"
BindingContext="{Binding Filtros}">
<Picker Title="Seleccione Fabricante"
Margin="15,5,15,5"
HorizontalOptions="FillAndExpand"
ItemsSource="{Binding Fabricantes, Mode=TwoWay}"
ItemDisplayBinding="{Binding Name}"
SelectedItem="{Binding Name}">
</Picker>
</StackLayout>
</ContentPage>
As noted, the StackLayout containing the Picker is declared as follows in the MainViewModel
public FiltrosViewModel Filtros { get; set; }
Then in my FiltersViewModel.CS I declare the Observable Collection which will have my Picker control (in addition to initializing it in the constructor) and filled with an array which has two Id and Name properties
public ObservableCollection<Fabricante> Fabricantes { get; set; }
public FiltrosViewModel()
{
Fabricantes = new ObservableCollection<Fabricante>();
LoadFabricantes();
}
async void LoadFabricantes()
{
IsRunning = true;
//CONSUMING API...
var list = response.Fabricantes;
Fabricantes = new ObservableCollection<Fabricante>(list);
IsRunning = false;
}
How to show values ​​in Picker occupying MVVM with Xamarin
I want to Bindar an ObservableCollection of the Manufacturer Object and show its Name property in a Picker occupying the MVVM pattern in Xamarin, but I'm not getting results (Blank Picker)
This Picker is displayed in the View FiltersSisquimView.xaml as follows
As noted, the StackLayout containing the Picker is declared as follows in the MainViewModel
Then in my FiltersViewModel.CS I declare the Observable Collection which will have my Picker control (in addition to initializing it in the constructor) and filled with an array which has two Id and Name properties
As you can see, I am correctly filling the Observable Collection "Fabricantes"
But how can I show the Name property in the Picker? I am new working with MVVM and I have in mind that I am correctly fitting the ViewModel to the Main (since my other controls work)
As once the user selected the name, can I rescue the ID of that Name, any help for me?

The problem is this line:
Fabricantes = new ObservableCollection<Fabricante>(list);
When you new up an ObservableCollection you lose the actual binding. You either need to set the BindingContext then again, but that is not what you would want. Instead, clear the existing collection and repopulate it. For example, like this:
var list = response.Fabricantes;
Fabricantes.Clear();
foreach (var item in list)
Fabricantes.Add(item);

C# WPF Checkbox Databinding

I'm looking for the best way to populate a check boxes from the following code. I have looked into Binding but not really sure where to go.
Here is the edited code that is working
private void dpDateSelection_SelectedDateChanged(object sender, SelectionChangedEventArgs e)
{
DateTime? date = dpDateSelection.SelectedDate;
logDate = date != null ? date.Value.ToString("yyyy-MM-dd") : null;
dpDateSelection.ToolTip = logDate;
LoadLogs(logDate);
}
private void LoadLogs(string ldate)
{
string[] logs = Directory.GetFiles(logPath + ldate, "*.ininlog");
InitializeComponent();
logList = new ObservableCollection<String>();
logList.Clear();
foreach (string logName in logs)
{
string s = logName.Substring(logName.IndexOf(ldate) + ldate.Length + 1);
int extPos = s.LastIndexOf(".");
s = s.Substring(0, extPos);
logList.Add(s);
}
this.DataContext = this;
}
<ListBox x:Name="Logs" ItemsSource="{Binding logList}">
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox Content="{Binding}" ToolTip="{Binding}" Tag="{Binding}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>

You will want to start by using an ItemsControl instead of a StackPanel, since ItemsControls are automatically set up to display collections of things:
<ItemsControl ItemsSource="{Binding Logs}"/>
Note the use of ItemsSource. With the accompanying binding string, it basically says "Look for a property on the DataContext called "Logs" and put everything in it into this control".
Next you said you wanted this displayed as checkboxes, so we use an item template:
<ItemsControl ItemsSource="{Binding Logs}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<CheckBox Content={Binding .}/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
This says "Use a checkbox for each Item in the ItemsSource". The DataTemplate can be a Grid or other collection control as well, so this is a really powerful feature in WPF. The "Binding ." just binds to the object itself (a string in this case, so we don't need a special path).
Finally, you need to set up a property to bind to in your view model:
ObservableCollection<String> Logs {get; set;}
You want an ObservableCollection so that when anything is added to or removed from the list, it automatically updates the UI. If you are going to be completely replacing the list (assignment), then you need to implement INotifyPropertyChanged and invoke the PropertyChanged event in that properties setter.
In your posted loop, you would add each log file to this property.
Also, make sure that somewhere you set the DataContext property of the XAML file (View) to your view model object. If everything is in code behind, use DataContext = this. Note that doing this is considered bad practice, and you should use a separate class (ViewModel).
You didn't mention what you wanted the CheckBoxes to do, so I haven't included anything related to that in my answer. You will likely want to abstract your logs into an object with a "Selected" property you can then bind the IsChecked property of the CheckBoxes to.
Obviously this is a lot to take in, please let me know if I can clarify anything or help further!
Update
You put the property in your ViewModel (DataContext). Whatever class that is, you write:
ObservableCollection<String> Logs {get; set;}
private void LoadLogs()
{
string[] logs = Directory.GetFiles(logPath + logDate, "*.ininlog");
foreach(string logName in logs)
{
string s = logName.Substring(logName.IndexOf(logDate) + logDate.Length + 1);
int extPos = s.LastIndexOf(".");
s = s.Substring(0, extPos);
//MessageBox.Show(s);
Logs.Add(s); //Add the parsed file name to the list
}
}

Creating Image control dynamically inside a listbox based on number of items user wants using C#

Simple question but I am totally confused. I am developing a wp7 app using C#. I want a listbox with input number of image item which source should be same i.e. the list box should contain 'n' Image control with source set to a single image where 'n' is number of Listbox Item enter by user. e.g. If the user input '10', then the listbox should have ten items. I want the listbox ItemsPanelTemplate as Wrap-panel. Can somebody suggest me how to get this?

Define a ListBox in your XAML something like this
<ListBox x:Name="ListBoxImages">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<Image Source="{Binding Imagesource}" Width="300"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
and then set its Source in the code behind like this
int noOfImages = 10; //Take the input from user
List<ImageClass> imageList = new List<ImageClass>();
for(int i=0; i<noOfImages; i++)
imageList.Add(new ImageClass() { Imagesource = "/user.jpg" });
ListBoxImages.ItemsSource = imageList; //Set the source of the listbox here
where ImageClass is,
public class ImageClass
{
public String Imagesource { get; set; }
}
The above is a sample for your understanding. Please customize wisely to suit your needs

Show Email body in textbox from listbox Imap/pop3

So I have a listbox that shows the subject of an email (I use the chilkat imap client) when I select the subject of an email I want to show the message body in a textbox but i cant figure out how to do it, obviusly i use the listbox selectindexchanaged event but how would i go about it
Code So Far
// Create an object, connect to the IMAP server, login,
// and select a mailbox.
Chilkat.Imap imap = new Chilkat.Imap();
imap.UnlockComponent("UnlockCode");
imap.Connect("Imap URL");
imap.Login("email address", "password");
imap.SelectMailbox("Inbox");
// Get a message set containing all the message IDs
// in the selected mailbox.
Chilkat.MessageSet msgSet;
msgSet = imap.Search("ALL", true);
// Fetch all the mail into a bundle object.
Chilkat.EmailBundle bundle = new Chilkat.EmailBundle();
bundle = imap.FetchBundle(msgSet);
// Loop over the bundle and display the From and Subject.
Chilkat.Email email;
int i;
for (i = 0; i < bundle.MessageCount - 1; i++)
{
email = bundle.GetEmail(i);
listBox1.Items.Add(email.From + ": " + email.Subject);
textBox1.Text = email.Body ;
}
// Save the email to an XML file
bundle.SaveXml("bundle.xml");
// Disconnect from the IMAP server.
// This example leaves the email on the IMAP server.
imap.Disconnect();
}
}
thanks in advance

Assuming that the email indexes stay the same (I think the safest way to make sure of that would be to cache the fetched bundle in the form), I'd change to using a ListView instead of the ListBox and then I'd add the indexes to the list, either as a separate column or in the Tag of the items.
After you'd set up the ListView to look as you need it to look (ListView.View = View.Details; and ListView.MultiSelect = false; are probably the main ones) instead of:
listBox1.Items.Add(email.From + ": " + email.Subject);
you could do something like (if you do it the Tag way, which is slightly easier but some people think is bad):
listView1.Items.Add(email.From + ": " + email.Subject).Tag = i;
And then when the user selects a subject in the list, as you say, you handle the ListView.SelectedIndexChanged event and then just do something like:
if(ListView.SelectedItems.Count > 0)
{
textBox1.Text = bundle.GetEmail((int)ListView.SelectedItems[0].Tag).Body;
}
Or if you're sure you only ever want to get out the text from the emails, you could insert the texts into the tags instead of the indexes.

In your xaml set up the listboxes to bind to the properties you'd like, and set up event handlers for when the selection changes.
<StackPanel>
<ListBox Name="listbox1" SelectionChanged="listbox_SelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=From}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<ListBox Name="listbox2" SelectionChanged="listbox_SelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Subject}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<TextBox Name="textbox1"></TextBox>
</StackPanel>
Then in your code behind. bind the listboxes to a list of the email objects.
listbox1.ItemsSource = emails;
listbox2.ItemsSource = emails;
finally you need to handle the event from the listboxes.
private void listbox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ListBox listbox = (ListBox)sender;
foreach (Email email in listbox.SelectedItems)
{
textbox1.Text = email.Body;
}
}
Please note this code is not tested.

Your issue is not with the email but with how you are displaying items in your form. You are trying to do things in a winforms way, which is fine for winforms (kind of) but really is pointless and code-heavy in WPF. You should do some reading about MVVM (plenty of questions here on the subject).
Here's a demo showing what you want to do using only a few lines of code that takes advantage of the binding infrastructure of WPF. You can create a new WPF app and copypaste the few lines (change my namespace and class names to match the app you create!) and see it in action.
There is one window. I'm simulating emails here; you'd get your emails and dump them in the collection:
public partial class MainWindow : Window
{
public ObservableCollection<FakeEmail> Emails { get; private set; }
public MainWindow()
{
Emails = new ObservableCollection<FakeEmail>();
// simulates emails being received; you would popoulate with valid emails IRL
Emails.Add(new FakeEmail
{ From = "herp", Subject = "derp", Message = "herp derp" });
Emails.Add(new FakeEmail
{ From = "foo", Subject = "bar", Message = "foo bar" });
Emails.Add(new FakeEmail
{ From = "Binding", Subject = "Rocks", Message = "Binding rocks" });
InitializeComponent();
}
}
/// <summary>
/// I don't have your libraries
/// </summary>
public sealed class FakeEmail
{
public string From { get; set; }
public string Subject { get; set; }
public string Message { get; set; }
}
I've added an ObservableCollection of type FakeEmail to the window. OCs work well with binds, as the collection notifies binds when elements are added or removed.
Next, the window. Please note, I'm not showing the <Window definition here, but I have named the window emailClient!
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<ListBox
x:Name="emailList"
ItemsSource="{Binding Emails, ElementName=emailClient}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock
Text="{Binding From}" />
<TextBlock
Text="{Binding Subject}"
TextWrapping="NoWrap"
TextTrimming="CharacterEllipsis" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<TextBlock
Grid.Column="1"
Text="{Binding SelectedValue.Message, ElementName=emailList, FallbackValue='Select an email pls'}" />
</Grid>
Some of the finer notes: The ListBox's ItemsSource is bound to the ObservableCollection I defined on the window. The ListBox will listen for items coming and going in that collection, and use the DataTemplate to display UI for each item in the colleciton.
For each FakeEmail the ItemTemplate finds, it creates a new instance of the DataTemplate and contents, and sets the DataContext of the template to the FakeEmail instance. That means, within the DataTemplate I can simply bind against the properties of a FakeEmail instance and everything gets wired up at runtime.
The ListBox has a property called SelectedValue, which I can use to show the email message. When you select an item in the ListBox, SelectedValue is the instance from ItemsSource that is the DataContext of the DataTemplate; that which is currently displayed in that item in the UI. So, in order to show the currently selected email's message, I just need to bind against the ItemSource's SelectedValue's Message property, since SelectedValue will be the currently selected email.
And that's it. No listening, no "\r\n" BS. A couple binds and an Observable collection.