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View Model Code Generator

The DevExpress MVVM Framework includes a source generator that produces boilerplate code for your View Models at compile time. You need to define a stub View Model class that defines the required logic. Our MVVM Framework analyzes your implementation and applied attributes to generate the final View Model class with all required boilerplate code.

• Base View Model

  Create a partial class. Add attributes to the class and its fields/methods:

  using DevExpress.Mvvm.CodeGenerators;
  
  [GenerateViewModel]
  partial class ViewModel {
      [GenerateProperty]
      string username;
      [GenerateProperty]
      string status;
  
      [GenerateCommand]
      void Login() => Status = "User: " + Username;
      bool CanLogin() => !string.IsNullOrEmpty(Username);
  }
  

• Generated View Model

  The generator inspects the base View Model and produces a partial class that complements your implementation with the following boilerplate code:

  • Properties
  • Property change notifications
  • Command declarations
  • INotifyPropertyChanged, INotifyPropertyChanging, IDataErrorInfo, ISupportServices implementation

  You can view and debug the generated View Model:

  partial class ViewModel : INotifyPropertyChanged {
      public event PropertyChangedEventHandler PropertyChanged;
  
      protected void RaisePropertyChanged(PropertyChangedEventArgs e) => PropertyChanged?.Invoke(this, e);
  
      public string Username {
          get => username;
          set {
              if(EqualityComparer<string>.Default.Equals(username, value)) return;
              username = value;
              RaisePropertyChanged(UsernameChangedEventArgs);
          }
      }
  
      public string Status {
          get => status;
          set {
              if(EqualityComparer<string>.Default.Equals(status, value)) return;
              status = value;
              RaisePropertyChanged(StatusChangedEventArgs);
          }
      }
  
      DelegateCommand loginCommand;
      public DelegateCommand LoginCommand {
          get => loginCommand ??= new DelegateCommand(Login, CanLogin, true);
      }
  
      static PropertyChangedEventArgs UsernameChangedEventArgs = new PropertyChangedEventArgs(nameof(Username));
      static PropertyChangedEventArgs StatusChangedEventArgs = new PropertyChangedEventArgs(nameof(Status));
  }
  

Prerequisites

Your project should meet the following requirements:

• C# 9+ (VB is not supported)
• .NET Framework v4.6.1+ or .NET Core v3.0+
• Visual Studio v16.9.0+

Prepare Your Project

Prepare your project as outlined below to enable support for View Models generated at compile time:

1. Add a reference to the DevExpress.Mvvm.v21.1+ or install the DevExpress.Mvvm NuGet package.

2. Install the DevExpress.Mvvm.CodeGenerators NuGet package in your project.

3. Set the language version to 9 in the .csproject file:

   <PropertyGroup>
       <LangVersion>9</LangVersion>
   </PropertyGroup>
   

   For .NET Core projects, set the IncludePackageReferencesDuringMarkupCompilation property to true additionally:

   <PropertyGroup>
       <IncludePackageReferencesDuringMarkupCompilation>true</IncludePackageReferencesDuringMarkupCompilation>
   </PropertyGroup>
   

Documentation

Refer to the following topic for more information:

• View Models Generated at Compile Time

Example

Refer to the following GitHub example:

• How to: Use View Models Generated at Compile Time