コード例 #1
0
ファイル: frmCFM2MDefault.cs プロジェクト: pbirch16/Repos
        //CRUD + Link Existing-Records Operations

        //CREATE
        //https://www.codeproject.com/Tips/893609/CRUD-Many-to-Many-Entity-Framework
        //Insert
        private void Create(Student student, Course course)
        {
            using (var ctx = new M2MCollegeContext())
            {
                //Add instances to context
                ctx.Students.Add(student);
                ctx.Courses.Add(course);

                //Add instance to navigation property
                student.Courses.Add(course);

                ctx.SaveChanges();
            }
        }
コード例 #2
0
ファイル: frmCFM2MDefault.cs プロジェクト: pbirch16/Repos
        //DELETE RELATIONSHIP
        //To delete relationship, instead of call Remove from context, we need to call it from
        //navigation property.
        private void DeleteRelationship(int studentId, int courseId)
        {
            using (M2MCollegeContext ctx = new M2MCollegeContext())
            {
                // Return one instance of each entity by primary key
                var student = ctx.Students.FirstOrDefault(s => s.StudentId == studentId);
                var course  = ctx.Courses.FirstOrDefault(c => c.CourseId == courseId);

                // Call Remove method from navigation property for any instance
                // course.Students.Remove(student) also works
                student.Courses.Remove(course);

                ctx.SaveChanges();
            }
        }
コード例 #3
0
ファイル: frmCFM2MDefault.cs プロジェクト: pbirch16/Repos
        private void SetupTestData()
        {
            using (M2MCollegeContext ctx = new M2MCollegeContext())
            {
                for (int i = 3; i < 8; i++)
                {
                    string studentName = "Student" + i.ToString();
                    string courseName  = "Course" + i.ToString();

                    var student = new Student {
                        StudentName = studentName
                    };
                    var course = new Course {
                        CourseName = courseName
                    };
                    Create(student, course);
                }
            }
        }
コード例 #4
0
ファイル: frmCFM2MDefault.cs プロジェクト: pbirch16/Repos
        //LINK
        private void InsertWithData(int studentId, int courseId)
        {
            /*
             * These steps apply to both entities
             *
             * 1 - create instance of entity with relative primary key
             *
             * 2 - add instance to context
             *
             * 3 - attach instance to context
             */
            using (var ctx = new M2MCollegeContext())
            {
                //1
                Student s = new Student
                {
                    StudentId = studentId
                };

                //2
                ctx.Students.Add(s);

                //3
                ctx.Students.Attach(s);

                //1
                Course c = new Course {
                    CourseId = courseId
                };

                //2
                ctx.Courses.Add(c);

                //3
                ctx.Courses.Attach(c);

                //Add instance to navigation property
                s.Courses.Add(c);

                ctx.SaveChanges();
            }
        }