title: How to Map Discriminator Column when base type is IdentittyUser?
body: <p>I customized <code>IdentityUser</code> and named it <code>User</code>. Now extending <code>User</code> as <code>Doctor</code> and <code>Secretary</code>.</p>
  <pre><code>using Microsoft.AspNetCore.Identity;
  //...
  
  public class User : IdentityUser
  {
      public string UserType {get; set;}
      //some props
  }
  
  public class Doctor : User
  {
      //some props
  }
  
  public class Secretary : User
  {
      //some props
  }
  
  //...
  </code></pre>
  <p>I know that EF Core will create a Discriminator as shadow property but I want to map this Discriminator to User.UserType property. So here is my configuration on DbContext:</p>
  <pre><code>builder.Entity&lt;User&gt;()
              .HasDiscriminator(u=&gt;u.UserType)
              .HasValue&lt;User&gt;(&quot;user&quot;)
              .HasValue&lt;Doctor&gt;(&quot;doctor&quot;)
              .HasValue&lt;Secretary&gt;(&quot;secretary&quot;);
  </code></pre>
  <p>I got this error when adding migration:</p>
  <pre><code>The CLR property 'UserType' cannot be added to entity type 'IdentityUser' because it is declared on the CLR type 'User'.
  </code></pre>
  <p>Why does this error happen? Is this the nice way I go?</p>
  <p>Do you know any proper way of making different types of users?</p>