Refresh my datagrid when add some records(WPF mvvm and ef)

Question

Introduction I am new in WPF and mvvm and therefore I try to master the basics by making a application of inventory management.

Tech-Stack

• Entity Framework database first
• WPF
• MVVM

Problem Description

An Add or Deleteoperation doesn't automatically updates my datagriddoesn't automatically updated.

I read lots of stuff on forums but nothing to do.

Code

ArticleViewModel

Class ArticleViewModel
{
    private GStockEntities context;

    public ArticleViewModel()
    {
        context = new GStockEntities();
    }

    public ObservableCollection<article> GetAllArticle()
    {
        ObservableCollection<article> Article = new ObservableCollection<article>();
        try
        {
            var query = (from a in context.articles select a).ToList();
            foreach (var item in query)
            {
                Article.Add(item);
            }
        }
        catch (Exception)
        {
            throw;
        }
        return Article;
    }

    public ObservableCollection<article> Article
    {
        get
        {
            return this.GetAllArticle();
        }
        set
        {
            Set(ref _Article, value);
        }
    }

    private void Add()
    {
        article Article = new article();
        Article.id_article = id;
        Article.nom = nom_Article;
        Article.id_categorie = GetIdCategoriByName(nom_categorie);
        Article.quantite = (int)qt;
        Article.prix_achat = (decimal)prix_achat;
        Article.prix_vente = (decimal)prix_vente;
        context.articles.Add(Article);
        context.SaveChanges();
    }
}

ViewModelBase

class ViewModelBase : INotifyPropertyChanged, INotifyDataErrorInfo
{
    public ViewModelBase()
    {
    }


    #region INotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;

    public void Notify([CallerMemberName]string propertyName = null)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

    }

    protected bool Set<TProperty>(ref TProperty attrib,
    TProperty value, [CallerMemberName]string propertyName = null)
    {
        if (!object.Equals(attrib, value))
        {
            OnPropertyChanging(propertyName, attrib, value);
            attrib = value;
            Notify(propertyName);
            OnPropertyChanged(propertyName);
            return true;
        }
        return false;
    }

    protected virtual void OnPropertyChanged(string propertyName) { }

    protected virtual void OnPropertyChanging(string propertyName,
    object oldValue, object newValue) { }
    #endregion

}

ArticleView

<DataGrid DockPanel.Dock="Right" 
 AutoGenerateColumns="False"
 Name="ArtDatagrid" 
 ItemsSource="{Binding Article}" 
 SelectedItem="{Binding SelectedArticle}"
 CanUserAddRows="True"> 
            <DataGrid.Columns>
                <DataGridTextColumn 
                     Header="Id" 
                     Binding="{Binding id_article}"
                     Width="*"/>
                <DataGridTextColumn
                     Header="Nom"
                     Binding="{Binding nom}" 
                     Width="*"/>
                <DataGridTextColumn 
                     Header="Nom de la categorie" 
                     Binding="{Binding nom_categorie}"
                     Width="*"/>
                <DataGridTextColumn 
                     Header="QT"
                     Binding="{Binding quantite}"
                     Width="*"/>
                <DataGridTextColumn 
                     Header="Prix d'achat" 
                     Binding="{Binding prix_achat}"
                     Width="*"/>
                <DataGridTextColumn 
                     Header="prix de vente" 
                     Binding="{Binding prix_vente}"
                     Width="*"/>
            </DataGrid.Columns>
        </DataGrid>
</DockPanel>

Answer 1

Because you add the new created article to the database but not to the ObservableCollection that is bound to the grid. One solution could be not to return the articles from the database directly in the getter. Instead you could use a local variable to store them:

private ObservableCollection<article> _article
public ObservableCollection<article> Article
{
    get
    {
        if (_article == null)
            _article = this.GetAllArticle();
        return _article;
    }
}

Then you can use that collection in the add method:

private void Add()
{
    article Article = new article();
    Article.id_article = id;
    Article.nom = nom_Article;
    Article.id_categorie = GetIdCategoriByName(nom_categorie);
    Article.quantite = (int)qt;
    Article.prix_achat = (decimal)prix_achat;
    Article.prix_vente = (decimal)prix_vente;
    context.articles.Add(Article);
    context.SaveChanges();
    _article.Add(Article);
}