c# - Using a Button_Click event to change textbox content using MVVM -

c# - Using a Button_Click event to change textbox content using MVVM -

i don't know if that's right title anyway. i'm switching winforms , trying larn wpf , mvvm methodology.

i have custom class, incident, used store info incidents occur team must respond to. building view display info in instances of class user, allow user manipulate it. there several pieces of datetime info need displayed - start, end, notification_received, actions_taken. need have little button set datetime.now each associated textbox alter underlying value of loaded instance of incident class.

i'm trying figure out how this. winforms, would've set textbox.text , incident.start (etc) datetime.now in same button_click function, understanding of mvvm i'm not supposed this, instead should bind textbox vm , update value of vm.

this i'm stuck. i'm pretty sure i'm on how binding, not part alter value of vm button_click function. please assist?

you're right - view-model should command change, , textbox should update through binding.

in mvvm pattern, code-behind used. instead of button_click method, need command binding:

<button command="{binding setalldatestonowcommand}"/>

the command executed when button pressed. setalldatestonowcommand command handler - should icommand property on view-model:

public icommand setalldatestonowcommand { get; private set; }

i tend utilize relaycommand mvvm lite toolkit create command handlers, because syntax clean , simple. command handler initialized in view-model's constructor. handler method passed relaycommand should set properties on selected incident object:

public yourviewmodel() { this.setalldatestonowcommand = new relaycommand(this.executesetalldatestonowcommand); } ... public void executesetalldatestonowcommand() { this.selectedincident.start = datetime.now; // etc. }

if bindings on textboxes correctly set up, , properties beingness set firing appropriate propertychanged events, should updated when properties set in command execution method.

however, i'd suggest should have view-model incident, implements inotifypropertychanged interface. command outlined above property on view-model. setting, example, start property on view-model should set property on incident object view-model (the "model" object), , should raise propertychanged event. otherwise, incident class have implement inotifypropertychanged, , line between model , view-model classes becomes less clear.

c# wpf mvvm