Trigger DelegateCommand without buttons

[achobanov]

I want to trigger a DelegateCommand without having the user click a button. For example - I currently have a search box and a button. In order to find something you need to type the value AND press the search button. Instead I would like the search to perform automatically when the user types the first 3 symbols.

[achobanov]

Guess that's a no?

[sigmarsson]

https://stackoverflow.com/questions/950770/autocomplete-textbox-in-wpf

[ghost]

This may be a necropost, but why not put the method the DelegateCommand points to in the set of the text that bound to the textbox?
private string _textboxText;
public string TextboxText
{
get => _textboxText;
set {
SetProperty(ref _textboxText, value);
if (_textboxText.length() >= 3)
MethodDelegatePointsTo();
}

Just make sure the Binding UpdateSourceTrigger is set to OnPropertyChanged.
Mode can be OneWayToSource or TwoWay

[achobanov]

Hi, James. Unfortunately that approach does not work. I don't understand why exactly, but the framework seems to only trigger setters once a DelegateCommand has been invoked. I assume it's related to optimizations, but it seems like it's holding the state in the View object and only once a command is executed does Prism update the ViewModel itself.

Looking at it now - I'm not exactly using Prism as originally intended. I'm not interested in MVVM, because I've decided to layer my application in a different way. The separation between Views and ViewModels is redundant in my architecture. But I'm also liking Prism and at this point I'm not going to be replacing it.

[brianlagunas]

To be clear, prism doesn't update any ViewModels directly. That happens via data binding. As @JamesDLynch stated, you need to set the UpdateSourceTrigger to PropertyChanged in order to invoke the setter on each keystroke.

[achobanov]

Oh, I've completely missed that last part about the 'UpdateSourceTrigger'. Thanks, Brian, for pointing that out. I'll try it out.