We Keep Coding

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.

WPF/MVVM: Dynamically add checkboxes to 2 ColumnGrid based on available Enums

I'm currently build a gui for a logger. The logger class has a enum Types with a couple of values defining the different log message types.
Now I want to create a gui for this logger. Part of this gui is a 2 column grid where a checkbox for each log message type is available. It shall be used to filter the log. In order to reduce future coding effort, I would like to add a checkbox for each available type of log message dynamically. So when ever a new value is added to Logger.Types the gui adapts automatically.
My xaml of the checkboxes look something like this:
<CheckBox Name="CheckBoxTypeInformation" Grid.Column="0" Grid.Row="1"
Content="{myControls:LocalizationMarkup 'LOGMSG_TYPE_INFORMATION'}"
Command="{Binding FilterTypeCommand}" CommandParameter="Information"
IsChecked="{Binding Path=FilterType[0]}"/>
So there is quite some work to be done for each checkbox:
Insert the cb into the 2 column grid in some manner by defining the Grid.Column and Grid.Row. The logic of it is not the problem
Set the Content with a custom LocalizationMarkup
Bind a command with dynamic CommandParameter. Here I would like to pass the actual enum value. But I was not able to do so in xaml atm.
Bind the IsChecked Property to an index in an array holding the IsChecked Status of all checkboxes.
I'm not quite shure how to handle this. As I understood it correctly I somehow have to add an ObservableCollection<> of a new custom class which has properties for each of the 4 wanted tasks.
I hope somebody can point me into the right direction on how to implement something dynamic as described in a propper mvvm/wpf manner.
Thank you very much!

I would't use a grid for that, but simply a List.
Define a classe named LogLevelViewModel with two properties
private string _logDetails;
public string LogLevelDetails
{
get
{
return _logDetails;
}
set
{
if (_logDetails == value)
{
_logDetails = value;
RaisePropertyChanged(nameof(LogLevelDetails));
}
}
}
private LogLevel _logLevel;
public LogLevel LogLevel
{
get
{
return _logLevel;
}
set
{
if (_logLevel == value)
{
_logLevel = value;
RaisePropertyChanged(nameof(LogLevel));
}
}
}
Then define on your view model a ObservableCollection LogLevelViewModels
On the constructor of the view model, you can populate it With:
foreach (LogLevel level in Enum.GetValues(typeof(LogLevel )))
{
LogLevelViewModels.Add(level );
}
On the XAML make sure to define a DataTemplate for LogLevelViewModel and that's it.

C# WPF How can I have multiple DataContext

I am very new to WPF so despite finding other similar threads, my code is a little different so I don't know how to apply those solutions to mine.
<grid>
<CheckBox
x:Name="sortChk"
Content="Sort Variables"
IsChecked="{Binding SortVariables}"
/>
<b:FlatButton Command="{Binding ClickCommand}">
<TextBlock Text="Compare" FontSize="13"></TextBlock>
</b:FlatButton>
</grid>
Code behind looks something like this
string dataset1FullPath = null;
string dataset2FullPath = null;
string dataset1FilePath = null;
string dataset2FilePath = null;
public bool SortVariables { get; set; }
public SingleCompareWindow(string path1, string path2)
{
InitializeComponent();
dataset1FullPath = path1;
dataset2FullPath = path2;
dataset1FilePath = System.IO.Path.GetDirectoryName(path1);
dataset2FilePath = System.IO.Path.GetDirectoryName(path2);
//DataContext = this;
DataContext = new DataCompareVM(dataset1FullPath, dataset2FullPath, dataset1FilePath, dataset2FilePath, SortVariables);
}
You can see that I have commented out DataContext = this. If I dont comment it out and remove the other DataContext, then my SortVariables variable will take the value of the checkbox. If I have the other DataContext for the button click, then the checkbox will not bind. I need it to bind as I pass it as a parameter to DataCompareVM().
I'm very new to WPF and MVVM so forgive my ignorance.

You can't have more than one DataContext for a WPF control, you should move your properties to the ViewModel.

Yes, you can have different data contexts for different elements. But here you're trying to replace the same, window data context.
What you can do is use the named element. Replace your commented line with:
sortChk.DataContext = this;
Now, for the longest answer: you're not really doing MVVM here. As Fildor mentions, you should instead move the SortVariables property to the DataCompareVM ViewModel.
Since you seem to be struggling with MVVM, I believe reading my introductory book will help you get things straight: Learn WPF MVVM.

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.

WPF Binding issue with updating values

I have a .xaml file and a .cs file that share value with Binding.
To make it simples, I have 1 button and 1 textbox. I want to button to be disabled when the textbox's text has no character.
Here is the two codes of the xaml for binding:
<TextBox Name="txtSend" Text="{Binding Path=CurrentText,UpdateSourceTrigger=PropertyChanged}"></TextBox>
<Button IsEnabled="{Binding Path=IsTextValid}" Name="btnSend">Send</Button>
The two properties in the .cs file look like that:
public string CurrentText
{
get
{
return this.currentText;
}
set
{
this.currentText = value;
this.PropertyChange("CurrentText");
this.PropertyChange("IsTextValid");
}
}
public bool IsTextValid
{
get
{
return this.CurrentText.Length > 0;
}
}
The this.PropertyChanged is simply a method that call PropertyChanged from INotifyPropertyChanged.
The problem is that I have to call the this.PropertyChange("IsTextValid"); in the Setter of the CurrentText to be able to have the button state change.
Question 1) Is it the good way to do it... if the rules become more complexe I might require to call a lot of PropertyChanged...?
Question 2) My button is enable when the form load. How can I make it check the method from the start?

Question 1: This is correct. There is no problem doing that. However you could take a look at the validation using the IDataErrorInfo. (Google search for it, and you will find a lot of good examples)
Question 2: make sure your "currentText" string is initialized with string.empty. Because if you did not initialized it, it will be null, and the getter for IsTextValid will throw an exception, and WPF will fail to retrieve the value.
Or do it like that:
public bool IsTextValid
{
get
{
return ! string.IsNullOrEmpty( this.CurrentText );
}
}

Your way of doing it is correct. If you are a bit lazy (as I am), you should have a look on the NuGet package Fody.PropertyChanged.
Your code would simplify to
public string CurrentText { get; set; }
public bool IsTextValid { get { return this.CurrentText.Length > 0; } }
Fody.PropertyChanged does the rest for you. It automatically adds the needed instructions to notify that CurrentText changed, and it even detects that IsTextValid depends on CurrentText and notifies for it, too.