Checkbox in Datagrid MVVM WPF

Question

The View ConfigRole has 2 columns, Name and IsEnabled(checkBox)with Button Edit for every row,

ConfigRole:

** If CheckBox is TRUE for a Row in ConfigRole View,when I click on Edit Button I get new View Button_Lists which has 2 columns Name_Button and IsEnabled(CheckBox)...and I modify TRUe or FALSe for every IsEnabled.

**My objectif is : When IsEnabled ConfigRole is FALSE, I want to get all the IsEnabled Button_Lists default to FALSE,

ButtonList:

this is my try code in Button_Lists Model:

 // get all of ButtonsList 
 public ObservableCollection<ButtonRoleMapClass> ButtonList
    {
        get { return _buttonList; }
        set
        {
            _buttonList = value;
            OnPropertyChanged("ButtonList");
        }
    }

    //viewRoleButton: the Name of selected row in ConfigRole
     public ButtonListViewModel(ViewRoleMapClass viewRoleButton)
    {               

        //If IsEnabled for row in ConfigRole is FALSE
        if (viewRoleButton.IsEnabled==false)
        {
            ObservableCollection<ButtonRoleMapClass> butsList = new ObservableCollection<ButtonRoleMapClass>();
            foreach (ButtonRoleMapClass button in _buttonList)
            {
                button.IsEnabled = false;
                butsList.Add(button);
            }
            _buttonList = butsList;                
        }

I want to get all CheckBox in Datagrid for View Button_Lists default is FALSE,

But with my code, I have this Error:

How can I fix it?

what's the error ? can you give the code of the view as well ? — Etienne
– Etienne, Commented Jun 7, 2017 at 2:00
Use ButtonList = butsList direct. Then your PropertyChanged should work. — Wolfgang Feneberg
– Wolfgang Feneberg, Commented Jun 7, 2017 at 6:22
No, _buttonList is the value;so _buttonList = butsList; is correct — devtunis
– devtunis, Commented Jun 7, 2017 at 8:03
Do you set the value of _buttonList anywhere? If so its initial value is null. — SOuser
– SOuser, Commented Jun 7, 2017 at 8:07

mm8 · Accepted Answer · 2017-06-07 09:49:52Z

2

Make sure that you have initialized the _buttonList by adding an if statement that check whether _buttonList is null. If you get rid of the exception, you know that the ObservableCollection hasn't been initialized

You probably also want to set the ButtonList property to the new collection:

public ButtonListViewModel(ViewRoleMapClass viewRoleButton)
{
    //If IsEnabled for row in ConfigRole is FALSE
    if (viewRoleButton.IsEnabled == false)
    {
        ObservableCollection<ButtonRoleMapClass> butsList = new ObservableCollection<ButtonRoleMapClass>();
        if (_buttonList != null)
        {
            foreach (ButtonRoleMapClass button in _buttonList)
            {
                button.IsEnabled = false;
                butsList.Add(button);
            }
        }
        ButtonList = butsList;
    }
}

answered Jun 7, 2017 at 9:49

mm8

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1 Comment

devtunis Over a year ago

It works now,when I verify if (_buttonList != null) Thanks a lot :)

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