Hide some object fields before outputing?

Question

Is it possible to hide certain fields before outputting it?

For the sake of simplicity let's say I have User and Image one user can have multiple images.

User

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public IEnumerable<Image> Images { get; set; }
}

Output

{
    Id: "1",
    Name: "Steve"
}

Now I want to output User with images and without. Is it possible to do something like this?
_db.Users.SingleOrDefault(x => x.Id == id).Except(x => x.Images);

This would be possible by adding [JsonIgnore] but it's not an option since I will want to output Images in some different request.
This would be possible by outputting anonymous objects but it's not an option.
This would be possible by creating DTO, but even so, how can I assign properties automatically from model to dto? Imagine that I have 30 fields, I don't want to assign them manually.

@Romoku from a glance looks like this is what I need. Thanks a lot, I will investigate further. — Stan, Aug 08 '13 at 17:27

score 0 · Accepted Answer · answered Aug 08 '13 at 17:33

0

Imagine that I have 30 fields, I don't want to assign them manually.

Automapper to the rescue!

PM> Install-Package AutoMapper

DTO:

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public IEnumerable<Image> Images { get; set; }
}

public class UserInfo
{
    public int Id { get; set; }
    public string Name { get; set; }
}

Code:

Mapper.CreateMap<User, UserInfo>();

var user = new User { Id = 1, Name = "Bob" };

var userInfo = Mapper.Map<User, UserInfo>(user);

return Json(new { userInfo });

answered Aug 08 '13 at 17:33

Dustin Kingen

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This isn't dynamic enough, image more complex system with 8 variables that may or may not be shown in result. – skmasq Aug 08 '13 at 21:46
This is only an example. Automapper has [a ton of features](https://github.com/AutoMapper/AutoMapper/wiki). – Dustin Kingen Aug 09 '13 at 00:04

score 0 · Answer 2 · answered Aug 08 '13 at 18:15

I think this is also a solution which is worth your attention: You can define some base class or interface which contains elements you want, something like this:

public class UserBase {
  public int Id {get;set}
  public string Name {get;set;}
}
public class User : UserBase {
  public IEnumerable<Image> Images { get; set; }
}

//or using interface, I think this is better
public class IUserBase {
  int Id {get;set}
  string Name {get;set;}
}
public class User : IUserBase {
  public int Id { get; set; }
  public string Name { get; set; }
  public IEnumerable<Image> Images { get; set; }
}

Then in your LINQ query, you can do something like this:

var result = users.Select(x=>(IUserBase)x);
foreach(var user in result)
   System.Diagnostics.Debug.Print(user.Id + " : " + user.Name);//There is no `Images` element here except using explicitly cast to User type.

I think what he want is, depending on database settings choose which properties to show. — skmasq, Aug 08 '13 at 21:45

Hide some object fields before outputing?

User

Output

2 Answers2