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Entity Framework - Duplicate Existing Classes, Code First?

I'm trying to think of a way to store actual templates of ticket items in my Entity Framework MVC project. The thing is, I've already done a Code First migration process in the past. What I need to do is create logic in my code to allow someone to save time creating a ticket by using pre-loaded data from a template. My current inheritance model uses an abstract class (MasterTicket) which is used as the parent since to me there can be multiple categories (a Google Calendar based task, "Appointment Task" and a purely internal task, "General Task"). Here's my parent abstract class:
[Table("Ticket")]
[ModelBinder(typeof(MasterTicketBinder))]
public abstract class MasterTicket
{
[Key]
public Guid id{ get; set; }
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ART { get; set; }
public DateTime openTime{ get; set; }
public DateTime? closeTime { get; set; }
private bool active = true;
public bool Active{ get => active; set => active = value; }
public string summary{ get; set; }
public string description{ get; set; }
public DateTime updateTime{ get; set; }
//TODO: Create foreign key relationship to user model
public Guid userUpdateId{ get; set; }
//TODO: Create foreign key relationship for tickets from other systems
public Guid externalAppId{ get; set; }
//TODO: Create foreign key relationship to user model
public Guid userOpenId{ get; set; }
public Guid? userCloseId { get; set; }
public Guid userOwnerId{ get; set; }
private int timesUpdated = 0;
public int TimesUpdated { get => timesUpdated; set => timesUpdated = value; }
public DateTime expectedCompletionTime{ get; set; }
public DateTime actualCompletionTime{ get; set; }
public List<MasterTicketItem> masterTicketItems{ get; set; }
public MasterTicket()
{
}
}
An here's an example of the concrete Google Calendar-based "Appointment Task" child:
[Table("AppointmentTickets")]
public class ApptTaskTicket : MasterTicket
{
public DateTime currentApptTime { get; set; }
public DateTime? endApptTime { get; set; }
public bool allDay { get; set; }
public string customerName { get; set; }
//TODO: Create foreign relationship
public Guid subjectPrsnlId { get; set; }
public string gCalEventId { get; set; }
public string customerPhone { get; set; }
public string customerEmail { get; set; }
public string preferredContactMethod { get; set; }
public List<ApptConfirmItem> apptConfirmItems { get; set; }
}
I know I can easily create a column for the MasterTicket class to indicate that it's a template, but to me I feel it's cleaner to have a separate "Template Table" if you will that will store pre-existing values that can be filled in with a form. In this case, I think I would WANT to create a duplicate class that would store said templates so that there are only several rows. What would be the best way to do this with Code First? Does someone feel I should take a different approach? Maybe DB First is a better way to go?
In case it matters, here's my DBContext for the Tickets:
// Code-Based Configuration and Dependency resolution
[DbConfigurationType(typeof(MySqlEFConfiguration))]
public class TicketDB : DbContext
{
public TicketDB(): base("AffirmativeServiceSystem.Properties.Settings.AffirmTaskManager")
{
}
public DbSet<MasterTicket> tickets { get; set; }
public DbSet<MasterTicketItem> ticketItems { get; set; }
}

Entity Framework code first create a superclass in two existing classes,

This is my first time here so sorry if I did not put the doubt by default. In my project I have two models class doubts and a class of works, I want to create a classification for both using a superclass, like the design pattern strategy. But I have a problem, the project state is advanced and I have used the doubt and works classes many times. Already tried in many ways, but either the error in the update-database or the error in what I had done before.
Does anyone know one way that I can implement a generic class classification for the doubts and works classes without many changes of what I had already done?
My code is below
public abstract class Classificable
{
[Key]
public int id { get; set; }
public virtual Classification classication { get; set; }
}
public class Doubt : Classificable
{
public int doubtID { get; set; }
public string question { get; set; }
public string content { get; set; }
public virtual Student student { get; set; }
public virtual Course course { get; set; }
public virtual Work work { get; set; }
public virtual ICollection<Answer> answers { get; set; }
}
public class Work : Classificable
{
public int workID { get; set; }
public string name { get; set; }
public string nameWork { get; set; }
public string filePath { get; set; }
public virtual Student student { get; set; }
public virtual Course course { get; set; }
public virtual ICollection<Doubt> doubts { get; set; }
}
public class DB_DIS : DbContext
{
public DB_DIS()
: base("name=DB_DIS")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Doubt>().ToTable("Doubts");
modelBuilder.Entity<Work>().ToTable("Works");
}
public virtual DbSet<Doubt> Doubts { get; set; }
public virtual DbSet<Work> Works { get; set; }
}`

What is the property or method in Classificable that you are trying to apply to Doubt and Work?
Have you written your data structure in such a way that is contains an id field AND workID feild?
In my experience, if you are trying to share properties between EF Classes you are better off sharing common fields. I've used it in the past for base classes of AuditableBase as follows:
public class AuditableBase
{
public string UpdateUserId { get; set; }
public DateTime UpdateDate { get; set; }
}
Then all my classes that I want to "Audit" will have a UpdateUserId and UpdateDate, and I can do some pre-save processing to set those based on the type of AuditableBase.

How to model with EntityFramework extensible fields for the entities

I have the following requirement, on my app the Entities will come with some fields, however the user needs to be able to add additional fields to the entity and then values for those fields.
I was thinking something like this but I am not sure if it would be a good approach or not.
The base class is an entity (Not sure which fields I need to add here)
public class Entidad
{
}
Then the Company Class will inherit from Entity
public class Empresa : Entidad
{
[Key]
public int Id { get; set; }
public string Nombre { get; set; }
public string NIT { get; set; }
public string NombreRepresentanteLegal { get; set; }
public string TelefonoRepresentanteLegal { get; set; }
public string NombreContacto { get; set; }
public string TelefonoContacto { get; set; }
public ICollection<CampoAdicional> CamposAdicionales { get; set; }
}
As you can see there is an ICollection of additional fields. that class would have the fieldname, type and id
public class CampoAdicional
{
[Key]
public int Id { get; set; }
public string NombreCampo { get; set; }
public Tiposcampo TipoCampo { get; set; }
}
and then the field value would be something like this:
public class ValorCampo
{
public Entidad Entidad { get; set; }
public CampoAdicional Campo { get; set; }
public string ValorTexto { get;set ; }
public int ValorNumerico { get; set; }
}
However I am not sure if this is the correct model classes for my scenario and whether it would create the tables correctly.

EF works with lazy load so at least there are several "virtual" missings.
In all properties that does not use primitive types and in collections.
Can you extend more than one entity with additional fields? If so you need that ValorCampo contains the entity (Entidad) but the entity should have the Id so you need to move the Id from Empresa to Entidad. Otherwise you need ValorCampo should refer to Empresa not to Entidad

How to add userId to every query without adding it to all domain classes?

I'm working with sqlite and the c# sqlite-net library.
Some of my entities:
public class Product
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
[MaxLength(50)]
public string Name { get; set; }
[MaxLength(50)]
public string Brand { get; set; }
[MaxLength(50)]
public string Type { get; set; }
[MaxLength(50)]
}
public class ProductImage
{
public int Id { get; set; }
public string Name { get; set; }
public string Container { get; set; }
public int ProductId { get; set; }
}
Now all entities belong to a user and the user should always work only with his own entities. So when I insert an entity in the database I want to store the userId with it.
However... I don't want to add the userId to all my domain classes.
I'm storing my entities like this right now:
await _databaseManager.GetDatabaseInstance().InsertAsync(entity);
and selecting like this:
var products = await _databaseManager.GetDatabaseInstance().Table().ToListAsync();
So is there a way with sqlite-net to add the userId to the database without adding it to all domain classes?

Doesn't it support inheritance, as in looking at the type's hierarchy? I would suggest it would, or at least should. So, if it does you could use an abstract base class or an interface. Something like this:
public abstract class StandardEntity {
public int UserId { get; set; } // decorate with attributes as necessary
}
And inherit:
public class Product : StandardEntity {
}

Many to Many self Join with Entity Framework Code First

Consider this Poco:
public class User
{
public int Id { get; set; }
public string Username { get; set; }
public string Fullname { get; set; }
}
Now i want to implement a follow technique where a user may follow other users so basically its self Many to Many relationship
problem is i don't know how exactly i can achieve this in Entity Framework Code-First ?
I thought of a linker Table :
public class UserFollow
{
public int Id { get; set; }
public int Follower { get; set; }
public int Following { get; set; }
public DateTime FollowDate { get; set; }
}
i want to be able to get All Followers and Following from every User Object?

This is quite simple using EF code-first as you only need the User POCO:
public class User
{
public int Id { get; set; }
public string Username { get; set; }
public string Fullname { get; set; }
public ICollection<User> FollowedUsers { get; set; }
}
The collection means that a User is related to other users.
PS: I noted you added a timestamp in your solution example. To achieve that you should still add the collection changing the generic type to whatever suits your needs.
Hope it helps.