Define a unique key by EF code first

Question

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Unique key with EF code first

How can I define a unique key by EF code first. this is my model:

public class Users {   
  ...
  public string Username { get; set; }
  ...
}

I want to make Username as a unique key.

Answer 1

By putting a key attribute

public class Users {   
  ...
  [Key]
  public string Username { get; set; }
  ...
}