What is the difference between DbContext.Add() and DbContext.DbSet<TEntity>.Add(TEntity)? When do you use one vs the other?

Question

In ms docs Razor pages tutorial the DbContext has a DbSet Students set

public class SchoolContext : DbContext {     public DbSet<Student> Students { get; set; } 

and in the OnPostAsync() method creates and then adds updated students using DbSet<TEntity>.Add(TEntity) method(documentation):

        var emptyStudent = new Student();         if (await TryUpdateModelAsync<Student>(             emptyStudent,             "student",   // Prefix for form value.             s => s.FirstMidName, s => s.LastName, s => s.EnrollmentDate))         {             _context.Students.Add(emptyStudent);             await _context.SaveChangesAsync(); 

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The MVC tutorial also has a DbContext that has a DbSet Students however in the StudentsController.cs Create() post method, it adds students directly calling DbContext.add() on the DbContext:

_context.Add(student);  await _context.SaveChangesAsync(); 

The only other difference I see is that in MVC the student was passed in as a parameter:

public async Task<IActionResult> Create([Bind("LastName,FirstMidName,EnrollmentDate")] Student student)      { 

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Is there any difference between the two? Can they be used interchangeably. When to use one or the other?

Answer 1

In the sources you can find out the implementation of InternalDbSet's (which is a concrete implementation of the abstract DbSet) Add method:

public override EntityEntry<TEntity> Add(TEntity entity)         => _context.Add(entity); 

which clearly means that it's just a facade over DbContexts Add.

Technically this means that both do exactly the same.

Answer 2

The source now looks a bit different from Wiktor's answer, but the docs provide this statement:

Many methods, including Add, Update, Attach, and Remove, have implementations on both DbSet and DbContext. These methods have exactly the same behavior for normal entity types.

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The exception to this rule is when using shared-type entity types, which were introduced in EF Core 5.0, primarily for many-to-many join entities.