CODEWITHSUNDEEP
c#wpfmvvm
Moritz
Moritz

Reputation: 389

Update Listview after database has updated (WPF + MVVM)

I've got a small WPF form with a Listview (bound to an observablecolletion)

    <ListView Name="Employees_Listview" ItemsSource="{Binding Employees, UpdateSourceTrigger=PropertyChanged}" SelectedItem="{Binding YourSelectedItem, Mode=TwoWay}" Height="86" IsSynchronizedWithCurrentItem="True">
        <ListView.View>
            <GridView>
                <GridViewColumn Header="FirstName" DisplayMemberBinding="{Binding FirstName}"/>
                <GridViewColumn Header="LastName" DisplayMemberBinding="{Binding LastName}"/>
            </GridView>
        </ListView.View>
    </ListView>

2 textboxes

<TextBox Name="FirstName" Width="136" Text="{Binding SelectedItem.FirstName, ElementName=Employees_Listview, Mode=TwoWay}" />
<TextBox Name="LastName" Width="136" Text="{Binding SelectedItem.LastName, ElementName=Employees_Listview, Mode=TwoWay}" />

and a button

<Button Command="{Binding UpdateEmployeeCommand}" Margin="0,0,10,0">Update</Button>

Both textboxes are bound to the selected item in listview so when I update a textbox value it will automatically reflect the changes in the listview. Now I would like to update the database first and if there is no error I would like to update the listview. My update code looks like this

    var container = ContainerConfig.Configure();
    using (var scope = container.BeginLifetimeScope())
    {
        var SelectedEmployee = scope.Resolve<IEmployeeRepository>();
        if (!SelectedEmployee.Update(YourSelectedItem))
        {
            MessageBox.Show("Datensatz konnte nicht aktualisiert werden!" + "\n" + "Bitte den Administrator verständigen!");
            return;
        };
    }

I tried to set the textbox mode to OneWay but due the fact it's bound to the SelectedItem I can't get the new textbox value, only the "old" listview value. How can I check and update my database first before refreshing the listview?

UPDATE Maybe I have to choose another approach like this: TextBox bound a new property declared

View

<TextBox Text="{Binding NewFirstName}" Width="123"></TextBox>

and my ViewModel

//TEST
private string newfirstname;


public string NewFirstName
{
    get { return newfirstname; }
    set
    {
        newfirstname= value;
        RaisePropertyChanged("NewFirstName");
    }
}
//TEST
public EmployeeEntity YourSelectedItem
{
    get
    {
        return _yourSelectedItem;
    }
    set
    {
        NewFirstName = value.FirstName;
        _yourSelectedItem = value;
        RaisePropertyChanged("YourSelectedItem");
    }
}

Guess this is not the best way to go :/

Upvotes: 1

Views: 1161

Answers (1)

Chris Mack
Chris Mack

Reputation: 5208

I would do it like this:

  1. Update the database.
  2. Either return the updated data entity from the update method, or, query the database after the update to retrieve the updated data entity.
  3. Update the object in your application with the new values.

I would strongly recommend having a unique identifier/ID both in your database and in your classes within the application to facilitate this if you don't already.

Also, you'd need to have INotifyPropertyChanged implemented on your Model classes, as updating an item within an ObservableCollection won't have any impact on your View, as ObservableCollection only raises notifications when the collection itself changes, e.g., add/remove, and not when properties of its members change.

Upvotes: 2

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