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Get TextBox name from WPF application with MVVM model in helper class

So I am trying to build a MVVM application with WPF and i am stuck with this problem:
In the view class, I have a list of textBoxes that I want to acces in order to validate the inputs.
So I managed to do this by writing in the view class, and it works:
var list = mainGrid.Children.OfType<TextBox>().ToList();
var dictOfTb = new Dictionary<string, string>();
foreach (var item in list)
{
dictOfTb.Add(item.Name, item.Text);
}
But the problem is that I am trying to respect the MVVM pattern and I should to this in a helper class, lets call it ModelsPageHelper, and access it from the View, because here what I am trying to do is to only get data from the UI and pass it to the viewModel to get a result, and then to display it.
So in this class I wrote a method,GetValuesFromTextBoxes(List<TextBox> textBoxes) and I am writing the same code, but now I get a message saying that TextBox does not contain a definition for Name.
So the question is, how can I do the same thing in the helper class to acces the names of those textBoxes?

To do MVVM properly you have to stop thinking about code to validate text boxes, and think about a ViewModel that validates itself, and a view that displays the state of the ViewModel.
For example, if you have a property called Foo which must have the value Bar, the code would look like this:
public string FooError { get; private set; }
private string foo;
public string Foo
{
get => return foo;
set
{
foo = value;
if (foo == "Bar") FooError = "";
else FooError = "Foo must be Bar";
NotifyPropertyChanged();
NotifyPropertyChanged(nameof(FooError));
}
}
and your XAML would look something like this:
<TextBox Text={Binding Foo}/>
<TextBlock Text={Binding FooError}/>
Then perhaps your save button could check for errors too.
I'd strongly advise you to look into INotifyDataErrorInfo, which is a great way to organise your errors in a way that WPF can easily display (instead of properties like FooError). It might seem like a lot of work the first time you use it, but it's great once you've got lots of controls and validation rules.

C# Windows 10 UWP Nested Listviews with Databinding

I have a app that retrieves comments from a website. I can programmatically add them to a StackPanel, calulating their indentation for comment replies but I'd like to learn how to bind a list of comments to a ListView and have it display correctly there.
My Comment Class looks like this:
class Comment
{
public List<Comment> Replies { get; set; }
public string Body { get; }
public int Level { get; set; }
public Comment(string BodyText)
{
Body = BodyText;
}
public Comment(string BodyText, List<Comment> replies, int level)
{
Body = BodyText;
Replies = replies;
Level = level;
}
}
So each Comment can have a List<> of comments (replies) to it and the Level variable indicates the depth of the comment.
What would be the process to set up a ListView so that I can bind a list of comments to it and those comments replies to those and so on? Or is there a better way to do this?
Thank you.
This is how I currently have it implemented which is visually correct but I'd like to use data binding rather than doing it through code.

Create a ListView, bind it's ItemsSource property to the list of top level comments. Use an ItemTemplate that contains the comment and another ListView in a vertical StackPanel. That inner ListView needs to get the same ItemTemplate it is in. I'm not sure if {StaticResource} will handle that, but it should.
If you use ObservableCollections this will actually be dynamic.

I recommend you to use the third party package WinRTXamlToolkit. Which contains a TreeView control that can meet your hierarchy requirements well. You can just bind the comments collection to the TreeView control code behind. Code example as follows:
Xaml Code
<controls:TreeView Width="400" MaxHeight="400" x:Name="Treeviewcomment">
<controls:TreeView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Body}"/>
<data:DataTemplateExtensions.Hierarchy>
<data:HierarchicalDataTemplate ItemsSource="{Binding Replies}" />
</data:DataTemplateExtensions.Hierarchy>
</DataTemplate>
</controls:TreeView.ItemTemplate>
</controls:TreeView>
Binding code
this.InitializeComponent();
ObservableCollection<Comment> comments = new ObservableCollection<Comment>
{
new Comment ("By the way,I have noticed that ..."),
new Comment("Has this been metioned anywhere before..",
new List<Comment>
{
new Comment("Delta upgrade..."),
new Comment("When only stuff that...",
new List<Comment> {
new Comment("That's blloby...")},
3)},
2),
new Comment("Just had to turn off..")
};
And the result:
Special nuget package for uwp: WinRT XAML Toolkit. And I also upload the above code example to GitHub.

How to control DynamicResource implementation in C#

In my program I would like to implement a DynamicResource from code-behind. Right now I am binding the Content of a Label to a string property in my Data Model...
<Label Content="{Binding DataModel.StringValue}" ... />
Following this question, I have implemented the string in my Data Model like so:
private string _stringValue = (string)Application.Current.Resources["nameOfResource"];
public string StringValue
{
get { return _cartsInSystem; }
set
{
_cartsInSystem = value;
NotifyPropertyChange(() => CartsInSystem);
}
}
I would like to make it so that every time the user changes the Resource Dictionary, this string value updates with the new value.
I am trying to achieve the same effect as something like this:
<Label Content="{DynamicResource nameOfResource}" ... />
Please let me know what I am doing wrong, and how I might correctly implement something like this.
UPDATE 1: As requested by #HighCore, this is an example of my code where I only have access to string values from code-Behind (or C# class)
(This is part of a ViewModel of a TreeView in my MainWindow)
//The "DisplayNames" for these nodes are created here and not accessible through xaml.
//This is because the xaml window has access to this code through it's itemsSource
private HierarchicalVM CreateCartsNode()
{
return new HierarchicalVM()
{
DisplayName = "Carts",
Children =
{
new CartConnection() { ConnectionDataModel = new CartConnectionModel(), DisplayName = "Cart Connection" },
new HierarchicalVM() {
DisplayName = "Cart Types",
Children = {
CreateCartType( new CartConfigModel() { DisplayName = "Default" }, new CartIO_Model() ),
},
Commands = { new Command(OpenAddCart) {DisplayName = "Add..."} }
}
}
};
}
This is the xaml of the above TreeView:
<!-- Tree view items & Functions -->
<TreeView ItemsSource="{Binding DataTree.Data}" ... />
Update 2: I have another perfect example of my problem...
I have a comboBox that has it's itemsSource bound to an ObservableCollection in my Data Model. Like so:
private ObservableCollection<string> _objCollection;
private string _notUsed = "Not Used";
private string _stop = "Stop";
private string _slow = "Slow";
public DataModel()
{
ObjCollection = new ObservableCollection<string>() { _notUsed, _stop, _slow };
}
public ObservableCollection<string> ObjCollection {...}
xaml:
<ComboBox ItemsSource="{Binding DataModel.ObjCollection}" ... />
If I want to make it so that the items in this comboBox change when the resource dictionary is changed, it looks like I'll need to handle it in C# rather than xaml.

After OP's UPDATE 2 and having a chat with him for a different question, I understood he was trying achieve localisation for his application. He would change Resource Dictionaries (for different languages) on the fly, and he wanted his C# code re-read/load values from Application.Current.Resources.
APPROACH ONE
After you changing the Resource Dictionary, You could use something like EventAggregator/Mediator to let other parts of the application (including ViewModels) know about Resource Dictionary change, and they respond to it by re-loading/reading resources/values from Application.Current.Resources
APPROACH TWO
OP doesn't want to introduce any new dependencies like EventAggregator/Mediator. So, I suggested this second approach. I know, it is not pretty, but here it goes..
You could have a global static event instead of EventAggregator/Mediaotr to let other parts of the application know that you swapped resource dictionary, and they will re-load/read values.
Read this answer about potential problems with static events and their subscriptions.

SelectedListIndex property of a databound ListBox cannot be set, why?

I avoided to ask this question, but the ListBox's selected index can no be set. I have read the other threads and applied the settings, but it doesn't work.
<ListBox ItemsSource="{Binding}"
HorizontalAlignment="Right"
Name="lstReading" Height="Auto"
SelectedIndex="{Binding BookmarkSelectedIndex}">
In the something.xaml.cs, I am settings
lstReading.DataContext = IQText;
Where, IQText is an IEnumerable<dictIQ> and includes the BookmarkSelectedIndex as data element. Other data elements from IQText can be used but the listindex can't be set. Could someone please let me know why?

Are you have BookmarkSelectedIndex inside of dictIQ class? So, you have one BookmarkSelectedIndex per item, not per collection!
You can create separate property BookmarkSelectedIndex outside of dictIQ or create class that inherited from ObservalbeCollection<dictIQ> and have additional property BookmarkSelectedIndex:
public class CollectionWithIndex: ObservalbeCollection<dictIQ>
{
public int BookmarkSelectedIndex { get; set; }
}
I hope you choose best solution suitable for you

use this code for select item at runtime...
List<Audio> lst = Audio.GetAudioFiles();
Audio aufile = new Audio { FileDisplayName = "Select Audio File" };
lst.Insert(0, aufile);
lstPickAudio.ItemsSource = lst;
string FileDisplayName="your condition"
lstPickAudio.SelectedItem = lst.Where(p => p.FileName == FileDisplayName).First();

Can't seem to get WPF DataBinding in my head

Ok, I'm no newbie at programming or C# as such, I just can't seem to get WPF's databinding straight in my head. My colleagues are raving about it (and yes, I will ask them as well) but right now I'm stumped.
Here's what I'd like to do for starters:
As an example I've got a list of things like this:
List<Thing> thingList = Source.getList();
Now normally I'd go
foreach(Thing t in thingList)
{
//add thing to combobox
}
But from what I can gather is that I can somehow not do this but use a databinding to populate the combobox for me.
What I can't seem to get is where do I put the 'thingList'? Do I make it a separate property somewhere? Where do I put that property?
I feel very stupid at the moment, as I've been struggling with this for a while now and I can't find any examples out there that make me understand this - probably very simple - concept.
Anyone out there willing to help me or point me at some step-by-step guide I might have missed?

Use ObservableCollection<T> for databinding in WPF. Where T is your class. See example below
public class NameList : ObservableCollection<PersonName>
{
public NameList() : base()
{
Add(new PersonName("A", "E"));
Add(new PersonName("B", "F"));
Add(new PersonName("C", "G"));
Add(new PersonName("D", "H"));
}
}
public class PersonName
{
private string firstName;
private string lastName;
public PersonName(string first, string last)
{
this.firstName = first;
this.lastName = last;
}
public string FirstName
{
get { return firstName; }
set { firstName = value; }
}
public string LastName
{
get { return lastName; }
set { lastName = value; }
}
}
Now in XAML. Go to resource tag
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:c="clr-namespace:SDKSample"
x:Class="Sample.Window1"
Width="400"
Height="280"
Title="MultiBinding Sample">
<Window.Resources>
<c:NameList x:Key="NameListData"/>
</Window.Resources>
<ListBox Width="200"
ItemsSource="{Binding Source={StaticResource NameListData}}" // Name list data is declared in resource
ItemTemplate="{StaticResource NameItemTemplate}"
IsSynchronizedWithCurrentItem="True"/>
xmnls:c will give you option to choose the class. Here you can choose c,d ,e x whatever but be sure it should be used earlier

When it comes to data-binding i've found that this page if read thoroughly answers most of the questions beginners have about it.
To answer the question: The alernative to adding all the items is to tell the ComboBox where to get its items from, this is done with the ItemsSource property.
You can either set this in XAML or in code, while you would need a binding expression in XAML a normal assignment should do in code:
comboBox.ItemsSource = thingList;
If you do not specify further how those objects in the list are to be displayed the ToString method will be called, unless overridden you will usually end up with the class-path of your object. There are two main ways of telling the application how to display the object:
The fist and more heavy option is Data Templates which is used for displaying complex data using controls (which in turn can have items and templates etc), the second way is using lightweight properties like DisplayMemberPath, which should be set to the name of the property which should be displayed (usually just a string).
If your list changes and the combo box should be updated on its own the source should implement INotifyCollectionChanged, in most cases you will use the standard implementation ObersableCollection<T>.

Most people would use WPF Databinding to populate the combobox but you don't have to.
You can add the items via code if you want to.
It's easy to get trapped into doing everything as it "should" be done without have a good reason for doing it that way (BTW, I'm not recommending you manually add the items, I'm just saying you can).
List<Thing> thingList = Source.getList();
foreach(Thing t in thingList)
{
combobox.Items.Add( t );
}