// ReSharper disable once UnusedMember.Local
// ReSharper disable once UnusedParameter.Local
static void Main(string[] args)
{
var lazyFactory = new SchoolContextFactory(true);
var defaultFactory = new SchoolContextFactory(false);
var factoryOptions = new DbContextFactoryOptions();
using (var dbContext = lazyFactory.Create(factoryOptions))
{
DbInitializer.Initialize(dbContext);
}
using (var dbContext = lazyFactory.Create(factoryOptions))
{
var student = dbContext.Students.First();
var deptName = student.Enrollments.First().Course.Department.Name;
Console.WriteLine($"Department name is '{deptName}'. LazyLoading enabled, no need to call .Include().");
Console.WriteLine("Querying instructor with an OfficeAssignment.");
var instructorWithOfficeAssignment = dbContext.Instructors.First(x => x.OfficeAssignment != null);
Console.WriteLine($"Instructor has {(instructorWithOfficeAssignment.OfficeAssignment == null ? "no (WTF? We just queried instructors with OfficeAssignment!)" : "an")} OfficeAssignment.");
}
using (var dbContext = lazyFactory.Create(factoryOptions))
{
var instructorAbercrombie = dbContext.Set <Instructor>().First(x => x.LastName == "Abercrombie");
var coursesOfinstructorAbercrombie = instructorAbercrombie.CourseAssignments.Select(x => x.Course);
var courseCount = coursesOfinstructorAbercrombie.Count();
Console.WriteLine($"Instructor Abercrombie has {courseCount} courses.");
}
using (var dbContext = defaultFactory.Create(factoryOptions))
{
var student = dbContext.Students.First();
try
{
// ReSharper disable once UnusedVariable
var deptName = student.Enrollments.First().Course.Department.Name;
Console.WriteLine("Oops... Something didn't work. LazyLoading should not be enabled by default.");
}
catch (ArgumentNullException)
{
Console.WriteLine($"{nameof(ArgumentNullException)} occured because LazyLoading was not enabled and .Include() was not called.");
}
Console.WriteLine("Querying instructor with an OfficeAssignment.");
var instructorWithOfficeAssignment = dbContext.Instructors.First(x => x.OfficeAssignment != null);
Console.WriteLine($"Instructor has {(instructorWithOfficeAssignment.OfficeAssignment == null ? "no (WTF? We just queried instructors with OfficeAssignment!)" : "an")} OfficeAssignment.");
}
}
protected SchoolContext CreateDbContext(ConnectionStringSelector connectionStringSelector, ContextInitializationOptions options)
{
SchoolContext ctx;
if (options == ContextInitializationOptions.CleanupData ||
options == ContextInitializationOptions.SeedSampleData)
{
using (ctx = _ctxFactory.Create(new DbContextFactoryOptions(), connectionStringSelector))
{
ctx.Database.EnsureDeleted();
if (options == ContextInitializationOptions.SeedSampleData)
{
DbInitializer.Initialize(ctx);
}
}
}
ctx = _ctxFactory.Create(new DbContextFactoryOptions(), connectionStringSelector);
ctx.Database.EnsureCreated();
ctx.Database.Migrate();
return(ctx);
}