将表值绑定到Combobox时出错 - wpf

Question

I have a combobox which should bind the data dynamically from the database .

The source of the combobox is a observable collection.

Steps I followed:

1. Declared a combobox :

    <ComboBox ItemsSource="{Binding populatecombobox.modeltogetusername }" Width="155" Margin="18,15,618,0"/> 

2. Created a class to get the data from the database :

    public class populatetab2combobox { public ObservableCollection<comboboxdata> modeltogetusername { get; set; } public void getdatausinglinq() { using (Operations_Productivity_ToolEntities context = new Operations_Productivity_ToolEntities()) { var a1 = from t1 in context.Test_ImportedAuditdata select t1; if (modeltogetusername == null) modeltogetusername = new ObservableCollection<comboboxdata>(); foreach (var a in a1.GroupBy(x => x.username).Select(x => x.FirstOrDefault())) { modeltogetusername.Add(new comboboxdata { username = a.username }); } } } } 

3. Instantiating the above mentioned class in viewmodel

    public class ViewModel: INotifyPropertyChanged { private populatetab2combobox _populatecombobox = new populatetab2combobox(); public populatetab2combobox populatecombobox { get { return _populatecombobox; } set { if (value != _populatecombobox) { _populatecombobox = value; OnPropertyChanged("populatecombobox"); } } } public ViewModel() { _populatecombobox.getdatausinglinq(); } 

   }

The expected output is :

Ren1
Ren2

The actual output is

Namespace.Model.comboxdata
Namespace.Model.comboxdata

Answer 1

You are getting the output of the ToString() method and you are binding to instances of comboboxdata class and not the username inside of it.

You have 2 options. First you can change your xaml to this notice how we bind to the property in the item template.

<ComboBox ItemsSource="{Binding populatecombobox.modeltogetusername }" Width="155" Margin="18,15,618,0">
  <ComboBox.ItemTemplate>
    <DataTemplate>
      <TextBlock Text="{Binding username}"/>
    </DataTemplate>
  </ComboBox.ItemTemplate>
</ComboBox>

Second you can override the ToString() method on comboboxdata to return the username