How to use ICommand for executing multiple methods after Buttonclick

Question

I have a lack of understanding how to use the ICommand inferface for executing multiple methods in a row. Ideally I would like to create a delegate that executes all of the following 4 methods by invoking it (but it doesn't have to be a delegate):

var mongo = DbConn(); //Connection to MongoDB
var artikel = GetArtikel(reorderView); //returns ObservableCollection
var reorder = GetReorder(artikel, reorderView); //returns ReorderModel
Insert(mongo, artikel, reorder); //inserts new reorder into the MongoDB database (one reorder has multiple articles(artikel))

The View (excerpt):

Code Behind:

public partial class addReorder : System.Windows.Window
    {
        ReorderViewModel nachbest;
        ArtikelViewModel artikel;            

        //IControllerNachbestellung controllerNachbestellung;
        //IModelNachbestellung modelNachbestellung;
        public ObservableCollection AnfCollection { get; set; }

        public addReorder() 
        {
            this.DataContext = new addReorderViewModel();
        }
    public addReorder(string hv)
        {
            InitializeComponent();
            //HV, BV, Projektleiter und Bauleiter holen
            var dbOracle = new Datenbank();
            txtBv.Text = dbOracle.GetBauvorhaben(hv);
            txtbHv.Text = hv;
            txtBauleiter.Text = dbOracle.GetBauleiter(hv);
            string pl = dbOracle.GetProjektleiter(hv);
            txtProjektleiter.Text = dbOracle.GetProjektleiter(hv);

            nachbest = new ReorderViewModel();
            artikel = new ArtikelViewModel();
            leftStPnl.DataContext = nachbest;
            rightStPnl.DataContext = nachbest;
            dgArtikel.DataContext = artikel;

            //Die Anforderungscollection wird befüllt         
            IAnforderungsgrund anfgruende = new Anforderungsgrund();
            AnfCollection = anfgruende.ListeAnforderungen();
            dgcbAnf.ItemsSource = AnfCollection;
            dgcbAnf.TextBinding = new Binding(AnfCollection.ToString());
        }
}

The ViewModel (need help here):

public class addReorderViewModel
    {
        //Hook to class DelegateCommand
        private readonly DelegateCommand

The ViewModel has a "hook" to the DelegateCommand.cs-Class: DelegateCommand.cs

public class DelegateCommand : System.Windows.Input.ICommand
    {
        private readonly Predicate _canExecute;
        private readonly Action _execute;

        public DelegateCommand(Action execute)
            : this(execute, null)
        {
        }

        public DelegateCommand(Action execute, Predicate canExecute)
        {
            _execute = execute;
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            if (_canExecute == null)
                return true;

            return _canExecute((parameter == null) ? default(T) : (T)Convert.ChangeType(parameter, typeof(T)));
        }

        public void Execute(object parameter)
        {
            _execute((parameter == null) ? default(T) : (T)Convert.ChangeType(parameter, typeof(T)));
        }

        public event EventHandler CanExecuteChanged;
        public void RaiseCanExecuteChanged()
        {
            if (CanExecuteChanged != null)
                CanExecuteChanged(this, EventArgs.Empty);
        }
    }

Questions:

What do I have to do to make the buttonclick execute the above mentioned 4 methods?
How do I add other buttonclick events (the view has about 5-10 buttons) into the ViewModel?
How does the ViewModel know about the current View that is open?

The methods inside the ViewModel:

public MongoCRUD DbConn()
        {
            //Connection to MongoDB database "avdb"
            var mongo = new MongoCRUD("avdb");
            return mongo; //return value needed for INSERT-METHOD!
        }

        public ObservableCollection GetArtikel()
        {
            //How many rows inside the datagrid dgArtikel?
            int countrows = view.dgArtikel.Items.Count;
            //How many Columns?
            int countcols = view.dgArtikel.Columns.Count;

            //Arrays
            DataGridRow[] row = new DataGridRow[countrows];
            DataGridCell[] RowColumn = new DataGridCell[countcols];
            string[] CellValue = new string[countcols];
            string[,] ds = new string[countrows, countcols];

            ObservableCollection artikel = new ObservableCollection() { };
            //Save all cell values inside multidimensional Array
            for (int i = 0; i < countrows; i++)
            {
                //Create object for each DataGridRow of dgArtikel
                row[i] = (DataGridRow)view.dgArtikel.ItemContainerGenerator.ContainerFromIndex(i);
                //Alle Spalten in der jeweiligen Zeile iterieren
                for (int j = 0; j < view.dgArtikel.Columns.Count; j++)
                {

                    RowColumn[j] = view.dgArtikel.Columns[j].GetCellContent(row[i]).Parent as DataGridCell;
                    //ATTENTION HARDCODING --> j==INDEX COMBOBOXCOLUMN!!!
                    if (j == 7) //<---!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
                    {
                        CellValue[j] = ((ComboBox)RowColumn[j].Content).Text;
                    }
                    else
                    {
                        CellValue[j] = ((TextBlock)RowColumn[j].Content).Text;
                    }

                    ds[i, j] = CellValue[j];
                }
                //The sequence must be the same as inside class ARTIKEL!  ATTENTION HARDCODING!
                var art = new Artikel
                {
                    Pos = ds[i, 0],
                    Artikelbezeichnung = ds[i, 1],
                    Artikelnummer = ds[i, 2],
                    Einheit = ds[i, 3],
                    Menge = ds[i, 4],
                    Einzelpreis = ds[i, 5],
                    Gesamtpreis = ds[i, 6],
                    Anforderungsgrund = ds[i, 7], //<---!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
                    Anforderungsnr = ds[i, 8],
                    Anforderer = ds[i, 9],
                    Bemerkungen = ds[i, 10]
                };
                if (art != null)
                    artikel.Add(art);
            }
            return artikel;
        }


         public ReorderModel GetReorder(ObservableCollection artikel, addReorderView reorderview)
         {             
            ReorderModel rom = new ReorderModel
            {
                Hv = view.txtbHv.Text,
                Bv = view.txtBv.Text,
                Bauleiter = view.txtBauleiter.Text,
                Empfaenger = view.cboxEmpfaenger.Text,
                Empf_Ansprechpartner = view.txtEmpfAnsprechpartner.Text,
                Empfaenger_Mail = view.txtEmpfMail.Text,
                Anlieferungsort = view.cboxAnlieferung.Text,
                Adressat = view.cboxAdressat.Text,
                Anschrift = view.txtAdresse.Text,
                Plz_Ort = view.txtPlzOrt.Text,
                Kontaktperson_Kontaktnr = view.txtAnsprechpartnerOrt.Text,
                Liefertermin = view.calLiefertermin.Text,
                Bearbeiter = view.cboxBearbeiter.Text,
                Telefon_Bearbeiter = view.txtBearbeiterTel.Text,
                Mail_Bearbeiter = view.txtBearbeiterMail.Text,
                Bestelldatum = view.calBestelldatum.Text,
                Bemerkung_oben = view.txtBemerkung.Text,
                Projektleiter = view.txtProjektleiter.Text,
                Angelegt_am = DateTime.Now.ToString(),
                artikelliste = artikel
            };
            return rom;
         }  

         public void Insert(MongoCRUD mongo, ObservableCollection artikel, ReorderModel rom)
         {
            foreach (var a in artikel)
            {
                mongo.InsertRecord("bestellteArtikel", a);
            }
            mongo.InsertRecord("nachbestellungen", nb);
            MessageBox.Show("Nachbestellung in Datenbank gespeichert!", "Erfolgreich!", MessageBoxButton.OK, MessageBoxImage.Information);
         }

This is the view design: This is the datagrid inside the view design (dummy example)

The GREEN BUTTON is the INSERT part I want to execute with the help of the ICommand interface, i.e. do the following after clicking:

Connect to MongoDB
Get me the observableCollection()
Get me the ReorderModel instance
Do the Insert into my database collection

XAML:

As you can see, the Outlook operation (orange button) is still tightly coupled in a very bad design with the BtnOutlook_Click event handler inside the CodeBehind. So after binding the Green SaveNb Button properly to those 4 methods mentioned I would go on with this button and other buttons, decoupling them one by one from the CodeBehind for better reusable and flexible code according to standard conventions.

BionicCode · Accepted Answer

Since you are using DelegateCommand you just have to initialize it properly:

AddReorderViewModel.cs

public ICommand SaveNb => new DelegateCommand

How to use ICommand for executing multiple methods after Buttonclick

Answers (2)

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