private static void ExplicitLoadQuotes()
{
var samurai = context.Samurais.FirstOrDefault(s => s.Name.Contains("Kikuchiyo"));
// Load only works for a single object
context.Entry(samurai).Collection(s => s.Quotes).Load();
context.Entry(samurai).Reference(s => s.Horse).Load();
/*
* // Filter loaded data using 'Query'. This only results in one db execution.
* // (Not possible with eager loading)
* var happyQuotes = context.Entry(samurai)
* .Collection(b => b.Quotes)
* .Query()
* .Where(q => q.Text.Contains("save"))
* .ToList();
*/
}
private static void ModifyingRelatedDataWhenNotTracked()
{
var samurai = context.Samurais.Include(s => s.Quotes).FirstOrDefault(s => s.Id == 19);
var quote = samurai.Quotes[0];
quote.Text = "Did you hear that again?";
using (var newContext = new SamuraiConsoleContext())
{
// Don't use this. It will update the parent samurai and all its quotes.
// Don't use: newContext.Quotes.Update(quote);
// ...use this instead. Will only modify the quote in the database.
newContext.Entry(quote).State = EntityState.Modified;
newContext.SaveChanges();
}
}
public void CanInsertSamuraiIntoDatabase()
{
var builder = new DbContextOptionsBuilder();
// Passing a name so the db can be used elsewhere using 'UseInMemoryDatabase' again.
builder.UseInMemoryDatabase("CanInsertSamurai");
using (var context = new SamuraiConsoleContext(builder.Options))
{
// context.Database.EnsureDeleted(); // Takes long time
// 'EnsureCreated' can be used to seed the database with the EF Core migrations
// context.Database.EnsureCreated();
var samurai = new Samurai();
context.Samurais.Add(samurai);
// Properties are non-nullable needs to be populated in advance, eg. the 'Name' field.
// Because the InMemory database is used, the samurai already gets its id when using 'Add', not 'SaveChanges'
// 'SaveChanges' only make sense when testing with a real databse.
// Use 'Samurais.Count' to check if added or:
Assert.AreEqual(EntityState.Added, context.Entry(samurai).State);
}
}