.Net Entity Framework SaveChanges is adding without add method
- by tmfkmoney
I'm new to the entity framework and I'm really confused about how savechanges works. There's probably a lot of code in my example which could be improved, but here's the problem I'm having.
The user enters a bunch of picks. I make sure the user hasn't already entered those picks.
Then I add the picks to the database.
var db = new myModel()
var predictionArray = ticker.Substring(1).Split(','); // Get rid of the initial comma.
var user = Membership.GetUser();
var userId = Convert.ToInt32(user.ProviderUserKey);
// Get the member with all his predictions for today.
var memberQuery = (from member in db.Members
where member.user_id == userId
select new
{
member,
predictions = from p in member.Predictions
where p.start_date == null
select p
}).First();
// Load all the company ids.
foreach (var prediction in memberQuery.predictions)
{
prediction.CompanyReference.Load();
}
var picks = from prediction in predictionArray
let data = prediction.Split(':')
let companyTicker = data[0]
where !(from i in memberQuery.predictions
select i.Company.ticker).Contains(companyTicker)
select new Prediction
{
Member = memberQuery.member,
Company = db.Companies.Where(c => c.ticker == companyTicker).First(),
is_up = data[1] == "up", // This turns up and down into true and false.
};
// Save the records to the database.
// HERE'S THE PART I DON'T UNDERSTAND.
// This saves the records, even though I don't have db.AddToPredictions(pick)
foreach (var pick in picks)
{
db.SaveChanges();
}
// This does not save records when the db.SaveChanges outside of a loop of picks.
db.SaveChanges();
foreach (var pick in picks)
{
}
// This saves records, but it will insert all the picks exactly once no matter how many picks you have.
//The fact you're skipping a pick makes no difference in what gets inserted.
var counter = 1;
foreach (var pick in picks)
{
if (counter == 2)
{
db.SaveChanges();
}
counter++;
}
There's obviously something going on with the context I don't understand. I'm guessing I've somehow loaded my new picks as pending changes, but even if that's true I don't understand I have to loop over them to save changes.
Can someone explain this to me?
