public DataTransformer(SnappetChallengeContext context)
{
_context = context;
domains = new List<Domain>();
students = new List<Student>();
exercises = new List<Exercise>();
subjects = new List<Subject>();
objectives = new List<Objective>();
}
public override void Import(SnappetChallengeContext context)
{
var assembly = Assembly.GetExecutingAssembly();
const string resourceName = "SnappetChallenge.DAL.DataImport.work.json"; // serialized JSON is embedded resource
var itemsToInsert = new List<StudentAnswer>();
using (var streamFromEmbeddedResource = assembly.GetManifestResourceStream(resourceName))
using (var sr = new StreamReader(streamFromEmbeddedResource))
using (var reader = new JsonTextReader(sr))
{
while (reader.Read())
{
if (reader.TokenType != JsonToken.StartObject) continue;
var obj = JObject.Load(reader);
var studentAnswer = new StudentAnswer
{
Correct = obj["Correct"].Value<int>() == 1, // explicit cast to bool
DateAdded = DateTime.Now,
Difficulty =
obj["Difficulty"].Value<string>().Equals("NULL") // handle weird NULL values, they serialize as string "NULL"
? null
: obj["Difficulty"].Value<double?>(),
Domain = obj["Domain"].Value<string>(),
ExerciseId = obj["ExerciseId"].Value<long>(),
LearningObjective = obj["LearningObjective"].Value<string>(),
Progress = obj["Progress"].Value<int>(),
Subject = obj["Subject"].Value<string>(),
SubmitDateTime = obj["SubmitDateTime"].Value<DateTime>(),
SubmittedAnswerId = obj["SubmittedAnswerId"].Value<long>(),
UserId = obj["UserId"].Value<long>(),
Id = obj["SubmittedAnswerId"].Value<long>() // this is doubled in SubmittedAnswerId..
};
itemsToInsert.Add(studentAnswer);
}
}
context.BulkInsert(itemsToInsert);
context.SaveChanges();
}
public abstract void Import(SnappetChallengeContext context);
private static void CreateDatabase(IList<SnappetChallengeRecord> data)
{
var subjects =
(
from record in data
group record by record.Subject
into grp
select new Subject { Description = grp.Key }
).ToList();
var domains =
(
from record in data
group record by new { record.Subject, record.Domain }
into grp
select new Domain.Entities.Domain { Description = grp.Key.Domain, Subject = subjects.FirstOrDefault(s => s.Description == grp.Key.Subject) }
).ToList();
// Include subject in the group by, because domain name is not guaranteed to be unique
var objectives =
(
from record in data
group record by new { record.Subject, record.Domain, record.LearningObjective }
into grp
select new LearningObjective
{
Description = grp.Key.LearningObjective,
Domain = domains.FirstOrDefault(d => d.Description == grp.Key.Domain && d.Subject.Description == grp.Key.Subject)
}
).ToList();
var exercises =
(
from record in data
group record by new { record.LearningObjective, record.ExerciseId }
into grp
select new Exercise
{
Difficulty = grp.First().Difficulty,
LearningObjective = objectives.FirstOrDefault(o => o.Description == grp.Key.LearningObjective),
ExternalId = grp.First().ExerciseId
}
).ToList();
int i = 0;
var users =
(
from record in data
group record by new { record.UserId }
into grp
select new User
{
ExternalId = grp.Key.UserId,
Name = names[i++]
}
)
.ToList();
var submittedAnswers =
(
from record in data
group record by new { record.ExerciseId, record.SubmittedAnswerId, record.UserId }
into grp
select new SubmittedAnswer
{
IsCorrect = grp.First().Correct,
SubmittedOn = grp.First().SubmitDateTime,
Progress = grp.First().Progress,
Exercise = exercises.First(e => e.ExternalId == grp.Key.ExerciseId),
SubmittedBy = users.First(u => u.ExternalId == grp.Key.UserId)
}
)
.ToList();
// for the sake of brevity I'm skipping the dependency inversion here
using (var context = new SnappetChallengeContext())
{
context.GetRepository<Subject>().AddRange(subjects);
context.GetRepository<Domain.Entities.Domain>().AddRange(domains);
context.GetRepository<LearningObjective>().AddRange(objectives);
context.GetRepository<Exercise>().AddRange(exercises);
context.GetRepository<User>().AddRange(users);
context.GetRepository<SubmittedAnswer>().AddRange(submittedAnswers);
context.Commit();
}
Console.WriteLine("Database created succesfully");
}