private static void ModifyingRelatedDataWhenTracked()
{
var samurai = context.Samurais.Include(s => s.Quotes).FirstOrDefault(s => s.Id == 19);
samurai.Quotes[0].Text = "Did you hear that?";
context.Quotes.Remove(samurai.Quotes[2]);
context.SaveChanges();
}
private static void RemoveJoinBetweenSamuraiAndBattleSimple()
{
var join = new SamuraiBattle {
BattleId = 1, SamuraiId = 11
};
// Begin tracking and set state as deleted (only the delete call is performed on the database).
context.Remove(join);
context.SaveChanges();
}
private static void AddingQuoteToExistingSamuraiWhileNotTracked(int samuraiId)
{
var samurai = context.Samurais.Find(samuraiId);
samurai.Quotes.Add(new Quote
{
Text = "Now that I saved you, will you feed me dinner?"
});
using (var newContext = new SamuraiConsoleContext())
{
// Use 'Update' to start tracking the graph.
// As child's key value is not set state will automatically be set as 'added'
// Child's FK valueto parent, 'samuraiId', is set to parent\s key.
// Using Update
// Update will also make a db call to update the samurai, although no changes has been made
// newContext.Samurais.Update(samurai);
// Using Attach
// Use 'attach' instead when adding related objects, not editing the parent itself.
// This sets it state to 'unmodified' but still recognized
// the missing key and fk in the quote object.
// ...or just set the fk on the Samurai (se next method)
newContext.Samurais.Attach(samurai);
newContext.SaveChanges();
}
}
public int AddMultipleSamurais(string[] nameList)
{
var samuraiList = new List <Samurai>();
foreach (var name in nameList)
{
samuraiList.Add(new Samurai {
Name = name
});
}
_context.Samurais.AddRange(samuraiList);
var dbResult = _context.SaveChanges();
return(dbResult);
}
private static void AddSamurai()
{
var samurai = new Samurai {
Name = "Julie"
};
context.Samurais.Add(samurai);
context.SaveChanges();
}
private static void ReplaceAHorse()
{
// Horse already trached in memory:
var samurai = context.Samurais.Include(s => s.Horse).FirstOrDefault(s => s.Id == 18); // Already has a horse
/*
* Will throw, as the horse object needs to be in memory. EF will just send an insert to the db:
* samurai = context.Samurais.Find(23); // Already has a horse
* samurai.Horse = new Horse { Name = "Trigger" };
*/
// For 'horse trading' you can also set the horse's SamuraiId to the new samurai owner.
// The db call will first delete the old horse and the insert the new horse,
// because there can not be a horse without a samurai.
context.SaveChanges();
}
private static void InsertBattle()
{
context.Battles.Add(new Battle
{
Name = "Battle of Okehazma",
StartDate = new DateTime(1560, 05, 01),
EndDate = new DateTime(1560, 06, 15)
});
context.SaveChanges();
}
private static void QueryAndUpdateBattle_Disconnected()
{
// AsNoTracking returns a query, not a DbSet. DbSet methods like 'Find' won't be available.
var battle = context.Battles.AsNoTracking().FirstOrDefault();
battle.EndDate = new DateTime(1560, 06, 30);
using (var newContextInstance = new SamuraiConsoleContext())
{
// Update: Context will start tracking the object and mark its state as 'modified'
// Teis: I think 'Update' is only used in disconnected scenarios
newContextInstance.Battles.Update(battle);
newContextInstance.SaveChanges();
}
}
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();
}
}
private static void AddingQuoteToExistingSamuraiWhileNotTracked_Easy(int samuraiId)
{
var quote = new Quote
{
Text = "Now that I saved you, will you feed me dinner?",
// Somewhat 'unclean', but makes everything easier.
SamuraiId = samuraiId
};
using (var newContext = new SamuraiConsoleContext())
{
// ...or just set the fk on the Samurai (se next method)
newContext.Quotes.Add(quote);
newContext.SaveChanges();
}
}
public void CanInsertSamuraiIntoDatabase()
{
using (var context = new SamuraiConsoleContext())
{
// context.Database.EnsureDeleted(); // Takes long time
context.Database.EnsureCreated();
var samurai = new Samurai();
// Properties are non-nullable needs to be populated in advance, eg. the 'Name' field.
context.Samurais.Add(samurai);
Debug.WriteLine($"Before save: {samurai.Id}");
context.SaveChanges();
Debug.WriteLine($"After save: {samurai.Id}");
Assert.AreNotEqual(0, samurai.Id);
}
}
private static void AddNewHorseToDisconnectedSamuraiObject()
{
var samurai = context.Samurais.AsNoTracking().FirstOrDefault(s => s.Id == 18);
samurai.Horse = new Horse {
Name = "Mr. Ed"
};
samurai.Name += " Draiby";
using (var newContext = new SamuraiConsoleContext())
{
// Using the 'Attach' method, there os only one db call inserting into the Horses table.
// Teis: What if the Samurai object HAS beed changed? Will it then be updated as well?
// Teis: Answer: NO
// Teis: Probably no if samurais had foreign horse keys as well.
// EF Core sees that the samurai already has an id and will mark it as unchanged.
// but because the horse doesn't have an id, so its state will be set to 'added'.
newContext.Attach(samurai);
newContext.SaveChanges();
}
}
public void CanGetSamuraiWithQuotes()
{
int samuraiId;
var builder = new DbContextOptionsBuilder();
// Teis question: won't the reuse of the InMemory db name 'SamuraiWithQuotes'
// interfere with the previous test using the same name?
// Answer: The database is shared across tests but they don't interefere with each other (bad practice though)
builder.UseInMemoryDatabase("SamuraiWithQuotes");
using (var seedContext = new SamuraiConsoleContext(builder.Options))
{
var samuraiGraph = new Samurai
{
Name = "Kyūzō",
Quotes = new List <Quote> {
new Quote {
Text = "Watch out for my sharp sword"
},
new Quote {
Text = "I told you to watch out for my sharp sword! Oh well!"
}
}
};
seedContext.Samurais.Add(samuraiGraph);
seedContext.SaveChanges();
samuraiId = samuraiGraph.Id;
}
using (var context = new SamuraiConsoleContext(builder.Options))
{
// Check if the InMemory database is shared across tests (it is): var samurais = context.Samurais.ToList();
var bizlogic = new BusinessDataLogic(context);
var result = bizlogic.GetSamuraiWithQuotes(samuraiId);
Assert.AreEqual(2, result.Quotes.Count);
}
}