在 class 中自动填充属性

Question

Suppose that I have a class name User, is there any ways to populate the class properties and default value in Visual Studio as follow. I feel it is tedious to repeat typing the properties again and again.

Probably there is default shortcut to do this in Visual Studio or any extension that can do this?

Case 1

var user = db.User.Where(x => x.UserID).Select(o => new User
{
   UserId = o.UserId, // auto populate
   Username = o.Username, // auto populate
   ........  // auto populate all properties inside User class
}
);

case 2

var user = new User();
user.UserID = "",  // auto populate with type default value
user.Username = "",  // auto populate with type default value
........ // auto populate all properties inside User class
........ // auto populate all properties inside User class

Answer 1

I'm not quite sure what are you trying to achieve here

var user = db.User.Where(x => x.UserID).Select(o => new User
{
  UserId = o.UserId, // auto populate
  Username = o.Username, // auto populate
  ........  // auto populate all properties inside User class
}

since both new User and db.User are the same type of class/entity. But let's say you have an entity model User and a DTO/View model called UserViewModel and you want automatically to map the values of User to UserViewModel you can use automapper https://docs.automapper.org/en/stable/Getting-started.html Example this is the Entity definition

public class User 
{
   public int Id {get; set;}
  
   public string FirstName {get; set;}

   public string LastName {get; set;}
 
   public int Age {get; set;}
}

And we have a UserViewModel to which you want to map the data from User

  public class UserViewModel 
  {
     public int Id {get; set;}
  
     public string FirstName {get; set;}

     public string LastName {get; set;}
 
     public int Age {get; set;}
   }

With AutoMapper you can do this

 var configuration = new MapperConfiguration(config =>
 {
     config.CreateMap<User, UserViewModel>();
 }

and then you can use the mapper configuration like this

var user = db.User.Where(x => x.UserID).First();
var userViewModel = configuration.CreateMapper().Map<UserViewModel>(user);

This will automatically populate the property values of User to UserViewModel . Alternatively you can have a view model like this

public class UserViewModel 
{
     public int Id {get; set;}
  
     public string FullName {get; set;}
 
     public int Age {get; set;}
}

This time not all properties of User and UserViewModel match one to one and you will have to set a custom mapper configuration ie

var configuration = new MapperConfiguration(config =>
 {
     config.CreateMap<User, UserViewModel>()
           .ForMember(uvm => uvm.FullName, o => o.MapFrom($"{u.FirstName} {u.LastName}") );
 }

This way you are configuring the automatic User to UserViewModel mapping to map the FullName property value by concatenating FirstName and LastName from User

Answer 2

Well I have build a library that could solve this problem for you, called FastDeepCloner

   public class User 
    {

        public virtual string Name { get; set; } = "sdjh";

        public virtual int PasswordLength { get; set; } = 6;

        public Circular Test { get; set; } = new Circular();

    }
    
    public class CloneToTest
    {
        [FastDeepCloner.FastDeepClonerColumn("Name")] 
        [FastDeepCloner.FastDeepClonerColumn("LastName")] // Or
        public string FullName { get; set; }
        
        // You see here the type could be difrrent then the orginal type. 
        // FastDeepCloner will try to convert it, if it fail then a default value will be inserted insted
        public string PasswordLength { get; set; }
        
        // You could add a path insted, remember this only work on none list items.
        [FastDeepClonerColumn("Test.myBar.Id")]
        public int Id { get; set; }

        public Circular Test { get; set; }
    }

Now simple use

  var user = new User() { Name = "alen toma" };
        var cloneTo =new  CloneToTest();

        FastDeepCloner.DeepCloner.CloneTo(user, cloneTo);
  
        Assert.AreEqual(user.Name, cloneTo.FullName);