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Comments on C# WPF MVVM View & Get new record values
Parent
C# WPF MVVM View & Get new record values
+2
−0
Just looking to hear some reviews on my current MVVM Implementation, If I am heading towards the right direction. :)
Code
BaseViewModel
public class BaseViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
ViewModel
public class Technical_BestBeforeDates_ViewModel : BaseViewModel
{
// Loading + Filtering Data
private string _ProductCode;
public string ProductCode
{
get { return _ProductCode; }
set
{
_ProductCode = value;
OnPropertyChanged(nameof(ProductCode));
UpdateDataFromDatabase();
}
}
private string _ProductDescription;
public string ProductDescription
{
get { return _ProductDescription; }
set
{
_ProductDescription = value;
OnPropertyChanged(nameof(ProductDescription));
UpdateDataFromDatabase();
}
}
public ObservableCollection<Technical_BestBeforeDates_Model> BestBeforeDates_Models { get; }
public void UpdateDataFromDatabase()
{
BestBeforeDates_Models.Clear();
var records = Technical_BestBeforeData.GetFilteredData(ProductCode, ProductDescription);
foreach (Technical_BestBeforeDates_Model model in records)
{
BestBeforeDates_Models.Add(model);
}
}
// Open New Window Command
public ICommand OpenCreateNewRecordCommand { get; set; }
public void OpenWindow()
{
Technical_BestBeforeDates_CreateNewView window = new Technical_BestBeforeDates_CreateNewView()
{
WindowStartupLocation = System.Windows.WindowStartupLocation.CenterScreen,
DataContext = new Technical_BestBeforeDates_CreateNewViewModel()
};
window.ShowDialog();
}
// Constructor
public Technical_BestBeforeDates_ViewModel()
{
BestBeforeDates_Models = new ObservableCollection<Technical_BestBeforeDates_Model>();
UpdateDataFromDatabase();
OpenCreateNewRecordCommand = new RelayCommand(_ => OpenWindow());
}
}
CreateNewViewModel
public class Technical_BestBeforeDates_CreateNewViewModel : BaseViewModel
{
private Technical_BestBeforeDates_Model _NewModel_;
public Technical_BestBeforeDates_Model NewModel
{
get { return _NewModel_; }
set
{
_NewModel_ = value;
OnPropertyChanged(nameof(NewModel));
}
}
private string _ProductCode;
public string ProductCode
{
get { return _ProductCode; }
set
{
_ProductCode = value;
NewModel = new Technical_BestBeforeDates_Model
{
ProductCode = _ProductCode,
ProductDescription = this.ProductDescription
};
OnPropertyChanged(nameof(ProductCode));
}
}
private string _ProductDescription;
public string ProductDescription
{
get { return _ProductDescription; }
set
{
_ProductDescription = value;
NewModel = new Technical_BestBeforeDates_Model
{
ProductCode = this.ProductCode,
ProductDescription = _ProductDescription
};
OnPropertyChanged(nameof(ProductDescription));
}
}
public ICommand CreateNewRecordCommand { get; set; }
public void CreateNewRecord(object param)
{
var vm = param as Technical_BestBeforeDates_Model;
System.Windows.MessageBox.Show(vm.ProductCode);
}
public Technical_BestBeforeDates_CreateNewViewModel()
{
CreateNewRecordCommand = new RelayCommand(param => CreateNewRecord(param));
}
}
RelayCommand
public class RelayCommand : ICommand
{
private Action<object> execute;
private Predicate<object> canExecute;
private event EventHandler CanExecuteChangedInternal;
public RelayCommand(Action<object> execute)
: this(execute, DefaultCanExecute)
{
}
public RelayCommand(Action<object> execute, Predicate<object> canExecute)
{
if (execute == null)
{
throw new ArgumentNullException("execute");
}
if (canExecute == null)
{
throw new ArgumentNullException("canExecute");
}
this.execute = execute;
this.canExecute = canExecute;
}
public event EventHandler CanExecuteChanged
{
add
{
CommandManager.RequerySuggested += value;
this.CanExecuteChangedInternal += value;
}
remove
{
CommandManager.RequerySuggested -= value;
this.CanExecuteChangedInternal -= value;
}
}
public bool CanExecute(object parameter)
{
return this.canExecute != null && this.canExecute(parameter);
}
public void Execute(object parameter)
{
this.execute(parameter);
}
public void OnCanExecuteChanged()
{
EventHandler handler = this.CanExecuteChangedInternal;
if (handler != null)
{
handler.Invoke(this, EventArgs.Empty);
}
}
public void Destroy()
{
this.canExecute = _ => false;
this.execute = _ => { return; };
}
private static bool DefaultCanExecute(object parameter)
{
return true;
}
}
Data Storage - Technical_BestBeforeData
public static class Technical_BestBeforeData
{
private static List<Technical_BestBeforeDates_Model> GetData()
{
using (MySqlConnection conn = new MySqlConnection(ConfigurationManager.ConnectionStrings["MySQL"].ConnectionString))
{
conn.Open();
string query = @"SELECT b.id AS Id,
ProductCode,
ProductDescription,
b.AreaID as AreaID,
MinimumMonths,
LAST_DAY(DATE_ADD(NOW(), INTERVAL MinimumMonths MONTH)) AS BestBeforeDate
FROM technical_bestbeforedates b"; ;
var records = conn.Query<Technical_BestBeforeDates_Model>(query).ToList();
return records;
}
}
private static bool Filter(Technical_BestBeforeDates_Model tbm, string code, string description)
{
return (string.IsNullOrEmpty(code) || tbm.ProductCode.Contains(code)) && (string.IsNullOrEmpty(description) || tbm.ProductDescription.Contains(description));
}
public static IEnumerable<Technical_BestBeforeDates_Model> GetFilteredData(string code, string description)
{
return GetData().Where(tbm => Filter(tbm, code, description));
}
}
Model
public class Technical_BestBeforeDates_Model
{
public int Id { get; set; }
public string ProductCode { get; set; }
public string ProductDescription { get; set; }
}
Post
+3
−0
Some thoughts:
-
Consider using Github (or something like that, but I suggest Github due to its popularity) to share the project. It allows us not only to write some code but open PR with suggestions.
-
Do not use such names as
Technical_BestBeforeDates_Model, etc. Using of_is against C# style guide.PascalCaseis a preferable way.
Besides, it is hard to perceive.
I suppose, for Technical_BestBeforeDates_Model class you probably could:
- Use
Technicalas a name for namespace. - Remove
Modelpart. Put it to a separateModelproject to stress its purpose.
So Technical_BestBeforeDates_Model turns to Model.Technical.BestBeforeDates.
In short:
Name should be laconic and, at the same time, meaningfull.
-
BaseViewModel.
- Use
CallerMemberNameattribute - Use new version of C# to simplify null's check.
- To reduce boilerplate code you can add helpful
SetPropertymethod
protected virtual bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = "")
{
if (EqualityComparer<T>.Default.Equals(storage, value))
{
return false;
}
storage = value;
this.OnPropertyChanged(propertyName);
return true;
}
Technical_BestBeforeDates_ViewModel
-
VM should know nothing about View. Use services or consider using SPA (single page application) approach to navigate between pages.
-
Be careful with sending a query to DB each time user changes something in a field. You could use
Delay,Debounce, etc to prevent spamming. But maybe that's not the case here.
CreateNewViewModel
-
Use
camelCasefor fields. -
Passing something as a command parameter despite you have direct access to it that's odd.
public class Technical_BestBeforeDates_CreateNewViewModel : BaseViewModel
{
private string productCode;
public string ProductCode
{
get { return productCode; }
set { SetProperty(ref productCode, value); }
}
private string productDescription;
public string ProductDescription
{
get { return productDescription; }
set { SetProperty(ref productDescription, value); }
}
public ICommand CreateNewRecordCommand { get; set; }
public void CreateNewRecord()
{
var m = new Technical_BestBeforeDates_Model
{
ProductCode = productCode,
ProductDescription = this.ProductDescription
};
System.Windows.MessageBox.Show(m.ProductCode);
}
public Technical_BestBeforeDates_CreateNewViewModel()
{
CreateNewRecordCommand = new RelayCommand(_ => CreateNewRecord());
}
}
- Again, there should be no reference to any type that related to View (like
MessageBox)
Technical_BestBeforeData
- Name of this class doesn't reflect meaning.
- It would be better to filter data on a database side. It's usually faster there.
- Name of
GetDatamethod also doesn't reflect meaning. - You could move an sql query out of a method to keep them all together.
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