I'm learning Entity Framework, I was a bit confused between BLL and DAL, according to my search, I found that Entity Framework is DAL.
There are two ways to create BLL and DAL below:
First approach: write a separate DAO for each object (including add, remove, findAll, ...). In the BLL will call the DAO to get the data or modify the necessary data.
I have StudentManagement which inherits from DbContext and placed in the DAL.
public partial class StudentManagement : DbContext
{
public StudentManagement()
: base("name=StudentManagement")
{
}
public virtual DbSet<LOP> LOP { get; set; }
public virtual DbSet<STUDENT> STUDENT { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<LOP>()
.HasMany(e => e.STUDENT)
.WithOptional(e => e.LOP)
.HasForeignKey(e => e.CLASS_ID);
}
}
StudentDAO: query and modifying data if necessary.
class StudentDAO
{
public StudentManagement context { get; set; }
public StudentDAO()
{
context = new StudentManagement();
}
public IQueryable<STUDENT> findAll()
{
return context.STUDENT;
}
public void add(STUDENT student)
{
context.STUDENT.Add(student);
context.SaveChanges();
}
public void remove(int id)
{
STUDENT student = context.STUDENT.Find(id);
if (student != null)
{
context.STUDENT.Remove(student);
context.SaveChanges();
}
}
}
Student_BLL: call the StudentDAO to handle business and then return data to view.
class StudentBLL
{
public List<STUDENT> getStudentInClass(int ClassID)
{
return new StudentDAO().findAll().Where(student => student.CLASS_ID == ClassID).ToList();
}
public List<STUDENT> findAll()
{
return new StudentDAO().findAll().ToList();
}
public STUDENT find(int id)
{
return new StudentDAO().findAll().FirstOrDefault(student => student.ID == id);
}
public void add(STUDENT student)
{
new StudentDAO().add(student);
}
public void remove(int id)
{
new StudentDAO().remove(id);
}
}
Another approach: I don't have to create DAO for each object but use context in BLL and query directly using LINQ.
class LopSH_BLL
{
public StudentManagement context { get; set; }
public LopSH_BLL()
{
context = new StudentManagement();
}
public List<LOP> findAll()
{
return context.LOP.ToList();
}
public LOP find(int id)
{
return context.LOP.Find(id);
}
public void add(LOP lop)
{
context.LOP.Add(lop);
context.SaveChanges();
}
public void remove(int id)
{
LOP lop = context.LOP.Find(id);
context.LOP.Remove(lop);
context.SaveChanges();
}
}
Which is better and does it follow the rules of 3 layers?
