如何在WPF中有效地在组合框中添加项目

Question

I am a C++ developer and have recently started learning WPF. I am working on a wpf app where I am using MVVM. I have comboboxes and I need to add items in it. Although I generally use ComboboxPropertyName.Add("") to add items in it, I am looking for an efficient method which adds the items without much code length. Here is the code:

XAML:

<ComboBox Height="23" ItemsSource="{Binding BoardBoxList}" SelectedItem="{Binding SelectedBoardBoxList, Mode=TwoWay}" SelectedIndex="0" Name="comboBox2" />

ViewModel Class:

public ObservableCollection<string> BoardBoxList
    {
        get { return _BoardBoxList; }
        set
        {
            _BoardBoxList = value;
            OnPropertyChanged("BoardBoxList");
        }
    }

    /// <summary>
    /// _SelectedBoardBoxList
    /// </summary>
    private string _SelectedBoardBoxList;
    public string SelectedBoardBoxList
    {
        get { return _SelectedBoardBoxList; }
        set
        {
            _SelectedBoardBoxList = value;
            OnPropertyChanged("SelectedBoardBoxList");
        }
    }

Here Is how I had added items in my combobox in C++:

static const signed char boards[][9] = {
{},                                           // left blank to indicate no selection
{ 'S', '1', '0', '1', '0', '0', '1', '2', 0 },   // redhook
{ 'S', '1', '0', '1', '0', '0', '1', '8', 0 },   // bavaria
{ 'S', '1', '0', '1', '0', '0', '2', '0', 0 },   // flying dog
};

m_boardBox = new ComboBox(String::empty);
for(int i = 1; i < 4; i++)
    m_boardBox->addItem(String((char*)(boards[i])), i); 
m_boardBox->setSelectedId(2); // select Bavaria by default
addAndMakeVisible(m_boardBox);

If you notice above, you will find the loop adding items easily. This is how i wanna add items to my combobox.

If I use _BoardBoxList.Add("...."); I will have to use many .Adds. Is their an efficient way where I can store the items in a list/collection and add them into the combobox in the form of for loop just like above?

Please help :)

Answer 1

You can use a constructor of ObservableCollection that can consume an enumerable as a start set.

new ObservableCollection<string>(boards);

Boards would have to be an collection of strings not chars.

Edit:

var boards = new[]{ "S1010012" ,   // redhook
                   "S1010018",   // bavaria
                   "S1010020"    // flying dog
                  } 

Answer 2

There should be nothing stopping you from using the very same loop in C# to add items to the observable collection, the ComboBox will update automatically. Unless you are more specific about your problem there is nothing else to say.

The goal of the ItemsSource property is that you do not imperatively add items to the ComboBox itself via a loop but just specify a collection and the control will take care of the rest, how the items get into the collection if your business.

Answer 3

If i understand you correctly you can use AddRange Method of the List class

you can create list (add use AddRange - for adding, for loop, etc.), and than create Observable Collection based on that list.

ObservableCollection<string> collection 
                 = new ObservableCollection<string>(myList);

And than you can bind observable to ItemSource , if you need it (updating), otherwise you can bind list.

Answer 4

Use the ComboBox 's ItemsSource property. If you use an ObservableCollection as the source, you can forget updating the items manually and just work with the list in the view model.