entity framework DDD - entity-framework

Question

I work on a EF Core project for WPF app.
We decide to split the DbContext in 2 smaller Dbcontexts: (the project contains a single Database)
public class FirstDbContext : DbContext
{
public DbSet<Blog> Blogs { get; set; }
public DbSet<Post> Posts { get; set; }
public DBSet<Parameters>{ get; set; }
}
public class SecondDbContext: DbContext
{
public DBSet<User>{ get; set; }
public DBSet<Books> { get; set; }
public DBSet<Parameters>{ get; set; }
}
and we keep a "super" DbContext (which contains all the DbSets from the DB) to maintain and migrate the DB
public class SuperDbContext : DbContext
{
public DbSet<Blog> Blogs { get; set; }
public DbSet<Post> Posts { get; set; }
public DBSet<User>{ get; set; }
public DBSet<Books> { get; set; }
public DBSet<Parameters>{ get; set; }
}....
The first step to refactor code is to replace the lines which references the "SuperDbContext..." with the correct call "SecondDbContext.Books..."or "FirstDbContext.Post"... OK
Question:
In the Client app, the choice of DbContext is depending about a user's choice when app is launching: if user choose option1 => FirstDbContext, and if option2 => SecondDbContext.
How can we write the code to switch on the current DbContext to manage the "common DbSet" (Parameters) : before refactoring we have for example:
SuperDbContext.Parameters.FirstOrDefault()...
and now? do we have to write something like this:
if(option1)
{
FirstDbContext.Parameters.First()
}else
{
SecondDbContext.Parameters.First()
}
And what is the impact in the repositories? cause if we maintain this approach we have to duplicate code in the 2 Repositories?

Answer 1

No no... Forget about the approach you mentioned, you'll end up writing twice the code you need. Why don't you just use db context type :
At the beginning of your function, a single if else :
DbContext context;
if(option1)
{
context = new firstContextEntities();
}
else
{
context = new secondContextEntities();
}
And as both of your contexts are almost exactly the same, you will use your context by casting it to the greater one (the one that has the most access) :
var FirstLine = ((secondContextEntities)context).Parameters.First();