private async Task DeleteSteve(ManyToManyContext ctx)
{
Student steve = await ctx.Students.FirstAsync(s => s.StudentNum == 123456);
ctx.Students.Remove(steve);
await ctx.SaveChangesAsync();
}
private async Task UnEnrollSteveFromCourse(ManyToManyContext ctx)
{
StudentCourse steveAndDnp = ctx.Students.
Where(s => s.StudentNum == 123456)
.SelectMany(student => student.StudentCourses).
First(studentCourse => studentCourse.Course.CourseCode.Equals("IT-SDJ2-A20"));
ctx.Remove(steveAndDnp);
await ctx.SaveChangesAsync();
}
private async Task AddOneStudent(ManyToManyContext ctx)
{
Student s = new Student
{
FirstName = "Steve",
LastName = "Doe",
Email = "*****@*****.**",
StudentNum = 123456
};
await ctx.Students.AddAsync(s);
await ctx.SaveChangesAsync();
}
private async Task WhichCoursesIsSteveEnrolledIn(ManyToManyContext ctx)
{
List <Course> courses = await ctx.Students
.Where(s => s.StudentNum == 123456)
.SelectMany(student => student.StudentCourses)
.Select(studentCourse => studentCourse.Course)
.ToListAsync();
Console.WriteLine(JsonSerializer.Serialize(courses, new JsonSerializerOptions
{
WriteIndented = true
}));
}
private async Task EnrollSteveInDNP(ManyToManyContext ctx, string courseCode)
{
Student steve = await ctx.Students.FirstAsync(s => s.StudentNum == 123456);
Course dnp = await ctx.Courses.FirstAsync(c => c.CourseCode.Equals(courseCode));
StudentCourse sc = new StudentCourse
{
Course = dnp,
Student = steve
};
steve.StudentCourses = new List <StudentCourse>();
steve.StudentCourses.Add(sc);
ctx.Update(steve);
// ctx.Set<StudentCourse>().Add(sc); This is an alternative
await ctx.SaveChangesAsync();
}
public async Task RunExample()
{
using (ManyToManyContext ctx = new ManyToManyContext())
{
// await AddOneStudent(ctx);
// await AddTwoCourses(ctx);
// await EnrollSteveInDNP(ctx, "IT-DNP1Y-A20");
// await EnrollSteveInDNP(ctx, "IT-SDJ2-A20");
// await WhichCoursesIsSteveEnrolledIn(ctx);
// await DeleteSteve(ctx);
await UnEnrollSteveFromCourse(ctx);
List <Course> selectSpecific = await SelectSpecific(ctx,
course => new Course
{
Name = course.Name
}
);
}
}
private async Task AddTwoCourses(ManyToManyContext ctx)
{
Course sdj2 = new Course
{
Abbreviation = "SDJ2",
Name = "Software Development with UML and Java 2",
Semester = 2,
CourseCode = "IT-SDJ2-A20",
ECTS = 10
};
Course dnp1 = new Course
{
Abbreviation = "DNP1",
Name = "I forgot the actual name",
Semester = 3,
CourseCode = "IT-DNP1Y-A20",
ECTS = 5
};
await ctx.Courses.AddAsync(sdj2);
await ctx.Courses.AddAsync(dnp1);
await ctx.SaveChangesAsync();
}
private async Task <List <Course> > SelectSpecific(ManyToManyContext ctx, Expression <Func <Course, Course> > expression)
{
List <Course> enumerable = ctx.Courses.Select(expression).ToList();
return(enumerable);
}
