What’s the Context class for?

Question

I am developing a system in ASP.NET MVC with mapping using the Entity Framework, when observing some patterns I see a lot the use of the class Context, what it’s for and what it should contain anyway?

Answer 1

The Entity Framework implements a project standard called Repository. It has a complex mechanism that controls data access and gives an appearance of simplicity to your code. He doesn’t have all the information he needs to do, part of the code that he knows. How to join this complex mechanism with your code and everything seems one thing? Heritage. The class DbContext is this mechanism, so you inherit it from it and put what is missing, for example what are your tables, relationships and other settings of your model.

More about the class.

An example of its implementation:

namespace EFTutorials
{
    using System;
    using System.Data.Entity;
    using System.Data.Entity.Infrastructure;
    using System.Data.Entity.Core.Objects;
    using System.Linq;

    public partial class SchoolDBEntities : DbContext
    {
        public SchoolDBEntities()
            : base("name=SchoolDBEntities")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            throw new UnintentionalCodeFirstException();
        }

        public virtual DbSet<Course> Courses { get; set; }
        public virtual DbSet<Standard> Standards { get; set; }
        public virtual DbSet<Student> Students { get; set; }
        public virtual DbSet<StudentAddress> StudentAddresses { get; set; }
        public virtual DbSet<Teacher> Teachers { get; set; }
        public virtual DbSet<View_StudentCourse> View_StudentCourse { get; set; }

        public virtual ObjectResult<GetCoursesByStudentId_Result> GetCoursesByStudentId(Nullable<int> studentId)
        {
            var studentIdParameter = studentId.HasValue ?
                new ObjectParameter("StudentId", studentId) :
                new ObjectParameter("StudentId", typeof(int));

            return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction<GetCoursesByStudentId_Result>("GetCoursesByStudentId", studentIdParameter);
        }

        public virtual int sp_DeleteStudent(Nullable<int> studentId)
        {
            var studentIdParameter = studentId.HasValue ?
                new ObjectParameter("StudentId", studentId) :
                new ObjectParameter("StudentId", typeof(int));

            return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction("sp_DeleteStudent", studentIdParameter);
        }

        public virtual ObjectResult<Nullable<decimal>> sp_InsertStudentInfo(Nullable<int> standardId, string studentName)
        {
            var standardIdParameter = standardId.HasValue ?
                new ObjectParameter("StandardId", standardId) :
                new ("StandardId", typeof(int));

            var studentNameParameter = studentName != null ?
                new ObjectParameter("StudentName", studentName) :
                new ObjectParameter("StudentName", typeof(string));

            return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction<Nullable<decimal>>("sp_InsertStudentInfo", standardIdParameter, studentNameParameter);
        }

        public virtual int sp_UpdateStudent(Nullable<int> studentId, Nullable<int> standardId, string studentName)
        {
            var studentIdParameter = studentId.HasValue ?
                new ObjectParameter("StudentId", studentId) :
                new ObjectParameter("StudentId", typeof(int));

            var standardIdParameter = standardId.HasValue ?
                new ObjectParameter("StandardId", standardId) :
                new ObjectParameter("StandardId", typeof(int));

            var studentNameParameter = studentName != null ?
                new ObjectParameter("StudentName", studentName) :
                new ObjectParameter("StudentName", typeof(string));

            return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction("sp_UpdateStudent", studentIdParameter, standardIdParameter, studentNameParameter);
        }
    }
}

I put in the Github for future reference.

Source.