private static void AddSimpleGraph()
{
var essex = new Destination
{
Name = "Essex, Vermont",
Lodgings = new List <Lodging>
{
new Lodging {
Name = "Big Essex Hotel"
},
new Lodging {
Name = "Essex Junction B&B"
},
}
};
using (var context = new BreakAwayContext())
{
context.Destinations.Add(essex);
Console.WriteLine("Essex Destination: {0}", context.Entry(essex).State);
foreach (var lodging in essex.Lodgings)
{
Console.WriteLine("{0}: {1}",
lodging.Name,
context.Entry(lodging).State);
}
context.SaveChanges();
}
}
private static void SaveDestinationAndLodgings(
Destination destination,
List <Lodging> deletedLodgings)
{
// TODO: Ensure only Destinations & Lodgings are passed in
using (var context = new BreakAwayContext())
{
context.Destinations.Add(destination);
if (destination.DestinationId > 0)
{
context.Entry(destination).State = EntityState.Modified;
}
foreach (var lodging in destination.Lodgings)
{
if (lodging.LodgingId > 0)
{
context.Entry(lodging).State = EntityState.Modified;
}
}
foreach (var lodging in deletedLodgings)
{
context.Entry(lodging).State = EntityState.Deleted;
}
context.SaveChanges();
}
}
private static void ListenToLocalChanges()
{
using (var context = new BreakAwayContext())
{
context.Destinations.Local.CollectionChanged += (sender, args) =>
{
if (args.NewItems != null)
{
foreach (Destination item in args.NewItems)
{
Console.WriteLine("Added: " + item.Name);
}
}
if (args.OldItems != null)
{
foreach (Destination item in args.OldItems)
{
Console.WriteLine("Removed: " + item.Name);
}
}
};
context.Destinations.Load();
}
}
private static void CreatingNewProxies()
{
using (var context = new BreakAwayContext())
{
var nonProxy = new Destination();
nonProxy.Name = "Non-proxy Destination";
nonProxy.Lodgings = new List <Lodging>();
var proxy = context.Destinations.Create();
proxy.Name = "Proxy Destination";
context.Destinations.Add(proxy);
context.Destinations.Add(nonProxy);
var davesDump = (from l in context.Lodgings
where l.Name == "Dave's Dump"
select l).Single();
context.Entry(davesDump)
.Reference(l => l.Destination)
.Load();
Console.WriteLine("Before changes: {0}", davesDump.Destination.Name);
nonProxy.Lodgings.Add(davesDump);
Console.WriteLine("Added to non-proxy destination: {0}", davesDump.Destination.Name);
proxy.Lodgings.Add(davesDump);
Console.WriteLine("Added to proxy destination: {0}", davesDump.Destination.Name);
}
}
private static void AddMultipleDestinations()
{
using (var context = new BreakAwayContext())
{
context.Configuration.AutoDetectChangesEnabled = false;
context.Destinations.Add(new Destination
{
Name = "Paris",
Country = "France"
});
context.Destinations.Add(new Destination
{
Name = "Grindelwald",
Country = "Switzerland"
});
context.Destinations.Add(new Destination
{
Name = "Crete",
Country = "Greece"
});
context.SaveChanges();
}
}
private static void TestSaveDestinationGraph()
{
Destination canyon;
using (var context = new BreakAwayContext())
{
canyon = (from d in context.Destinations.Include(d => d.Lodgings)
where d.Name == "Grand Canyon"
select d).Single();
}
canyon.TravelWarnings = "Carry enough water";
canyon.State = State.Modified;
var firstLodging = canyon.Lodgings.First();
firstLodging.Name = "New Name Holiday Park";
firstLodging.State = State.Modified;
var secondLodging = canyon.Lodgings.Last();
secondLodging.State = State.Deleted;
canyon.Lodgings.Add(new Lodging
{
Name = "Big Canyon Lodge",
State = State.Added
});
ApplyChanges(canyon);
}
private static void FindGreatBarrierReef()
{
using (var context = new BreakAwayContext())
{
var query = from d in context.Destinations
where d.Name == "Great Barrier Reef"
select d;
var reef1 = query.Single();
//Throws exception if no one was found or found more than 1
var reef = query.SingleOrDefault();
//Throws exception if found more than 1
/* If two rows are found, Single and SingleOrDefault will throw because there is not a
* single result. If you just want the first result, and aren’t concerned if there is more than
* one result, you can use First or FirstOrDefault.*/
/* One important thing to remember is that LINQ queries against a DbSet always send a
* query to the database to find the data. So, if the Great Barrier Reef was a newly added
* Destination that hadn’t been saved to the database yet, the queries in Example 2-15
* and Example 2-16 won’t be able to locate it.*/
if (reef == null)
{
Console.WriteLine("Can't find the reef!");
}
else
{
Console.WriteLine(reef.Description);
}
}
}
private static void DeleteDestinationInMemoryAndDbCascade()
{
int destinationId;
using (var context = new BreakAwayContext())
{
var destination = new Destination
{
Name = "Sample Destination",
Lodgings = new List <Lodging>
{
new Lodging {
Name = "Lodging One"
},
new Lodging {
Name = "Lodging Two"
}
}
};
context.Destinations.Add(destination);
context.SaveChanges();
destinationId = destination.DestinationId;
}
using (var context = new BreakAwayContext())
{
var destination = context.Destinations
.Include("Lodgings")
.Single(d => d.DestinationId == destinationId);
var aLodging = destination.Lodgings.FirstOrDefault();
context.Destinations.Remove(destination);
Console.WriteLine("State of one Lodging: {0}",
context.Entry(aLodging).State.ToString());
context.SaveChanges();
}
}
private static void ReuseDbConnection()
{
var cstr = @"Server=.\SQLEXPRESS;
Database=BreakAwayDbConnectionConstructor;
Trusted_Connection=true";
using (var connection = new SqlConnection(cstr))
{
using (var context = new BreakAwayContext(connection))
{
context.Destinations.Add(new Destination {
Name = "Hawaii"
});
context.SaveChanges();
}
using (var context = new BreakAwayContext(connection))
{
foreach (var destination in context.Destinations)
{
Console.WriteLine(destination.Name);
}
}
}
}
static void RunTest()
{
using (var context = new BreakAwayContext())
{
context.Database.Initialize(force: true);
context.Destinations.Add(new Destination {
Name = "Fiji"
});
context.SaveChanges();
}
using (var context = new BreakAwayContext())
{
if (context.Destinations.Count() == 1)
{
Console.WriteLine(
"Test Passed: 1 destination saved to database");
}
else
{
Console.WriteLine(
"Test Failed: {0} destinations saved to database",
context.Destinations.Count());
}
}
}
private static void TestSaveDestinationAndLodgings()
{
Destination canyon;
using (var context = new BreakAwayContext())
{
canyon = (from d in context.Destinations.Include(d => d.Lodgings)
where d.Name == "Grand Canyon"
select d).Single();
}
canyon.TravelWarnings = "Carry enough water!";
canyon.Lodgings.Add(new Lodging
{
Name = "Big Canyon Lodge"
});
var firstLodging = canyon.Lodgings.ElementAt(0);
firstLodging.Name = "New Name Holiday Park";
var secondLodging = canyon.Lodgings.ElementAt(1);
var deletedLodgings = new List <Lodging>();
canyon.Lodgings.Remove(secondLodging);
deletedLodgings.Add(secondLodging);
SaveDestinationAndLodgings(canyon, deletedLodgings);
}
private static void ApplyChanges <TEntity>(TEntity root) where TEntity : class, IObjectWithState
{
using (var context = new BreakAwayContext())
{
context.Set <TEntity>().Add(root);
CheckForEntitiesWithoutStateInterface(context);
foreach (var entry in context.ChangeTracker
.Entries <IObjectWithState>())
{
IObjectWithState stateInfo = entry.Entity;
if (stateInfo.State == State.Modified)
{
entry.State = EntityState.Unchanged;
foreach (var property in stateInfo.ModifiedProperties)
{
entry.Property(property).IsModified = true;
}
}
else
{
entry.State = ConverterState(stateInfo.State);
}
entry.State = ConverterState(stateInfo.State);
}
context.SaveChanges();
}
}
private static void LocalLinqQueries()
{
using (var context = new BreakAwayContext())
{
context.Destinations.Load();
var sortedDestinations = from d in context.Destinations.Local
orderby d.Name
select d;
Console.WriteLine("All Destinations:");
foreach (var destination in sortedDestinations)
{
Console.WriteLine(destination.Name);
}
var aussieDestinations = from d in context.Destinations.Local
where d.Country == "Australia"
select d;
Console.WriteLine();
Console.WriteLine("Australian Destinations:");
foreach (var destination in aussieDestinations)
{
Console.WriteLine(destination.Name);
}
}
}
/* Entity Framework queries are written using a .NET Framework feature known as Language
* Integrated Query, or LINQ for short. As the name suggests, LINQ is tightly
* integrated with the .NET programming experience and provides a strongly typed query
* language over your model. Strongly typed simply means that the query is defined using
* the classes and properties that make up your model. This provides a number of benefits
* such as compile-time checks to ensure your queries are valid and the ability to provide
* IntelliSense as you write your queries.
* For Entity Framework this provider is known as LINQ to Entities and is responsible for taking
* your LINQ query and translating it into a SQL query against the database you are
* targeting. The information you supplied to Entity Framework about the shape of your
* model and how it maps to the database is used to perform this translation. Once the
* query returns, Entity Framework is responsible for copying the data into instances of
* the classes that make up your model. */
//----------------------------------------------
//Chapter 2 - Querying With DBContext
//----------------------------------------------
// Add example methods here
private static void PrintAustralianDestinations()
{
/* A DbContext (and its underlying ObjectContext) are responsible for managing and
* tracking changes to instances of the classes in its model. These classes are also responsible
* for managing a connection to the database. It’s important to ensure that any resources
* used to perform these operations are cleaned up when the DbContext instance
* is no longer needed. DbContext implements the standard .NET IDisposable interface,
* which includes a Dispose method that will release any such resources.
* The examples in this book will make use of the using pattern, which will take care of
* disposing the context when the using block completes*/
using (var context = new BreakAwayContext())
{
var query = from d in context.Destinations
where d.Country == "Australia"
select d;
/* The query is sent to the database when the first result is requested by the application:
* that’s during the first iteration of the foreach loop. Entity Framework doesn’t pull back
* all the data at once, though. The query remains active and the results are read from the
* database as they are needed. By the time the foreach loop is completed, all the results
* have been read from the database.
* One important thing to note is that Entity Framework will query the database every
* time you trigger an iteration over the contents of a DbSet. This has performance implications
* if you are continually querying the database for the same data. To avoid this,
* you can use a LINQ operator such as ToList to copy the results into a list. You can then
* iterate over the contents of this list multiple times without causing multiple trips to the
* database.*/
foreach (var destination in query)
{
Console.WriteLine(destination.Name);
}
}
}
static void Main(string[] args)
{
try
{
var destination = new Destination
{
Country = "Indonesia",
Description = "EcoTourism at its best in exquisite Bali",
Name = "Bali"
};
var lodging = new Lodging
{
Name = "Rainy Day Motel",
};
var cstr = @"Server=DESKTOP-D51E9P0; Database=BreakAway;User ID=sa;Password=l88888888";
//Data Source=DESKTOP-D51E9P0;Persist Security Info=True;User ID=sa;Password=***********
//Data Source=DESKTOP-D51E9P0;Initial Catalog=master;Persist Security Info=True;User ID=sa;Password=***********
using (var connection = new SqlConnection(cstr))
{
using (var context = new BreakAwayContext(connection))
{
context.Lodgings.Add(lodging);
context.SaveChanges();
}
}
}
catch (System.Data.Entity.Validation.DbEntityValidationException ex)
{
Console.WriteLine(" 保存失败! 错误信息：" + ex.Message);
}
Console.WriteLine("OK");
Console.Read();
}
static void DeleteDestinationInMemoryAndDbCascade2()
{
//NOTE:
//随同Destination一起删除以前存入的Loading数据。我们删除与Lodging提到的所有相关代码。
//由于内存中无Lodging，就不会有客户端的级联删除，而数据库却清除了任何孤立的Lodgings数据，
//这是因为在数据库中定义了级联删除。
Guid destinationId;
using (var context = new BreakAwayContext())
{
var destination = new AnnotationModel.Destination
{
Name = "Sample Destination",
Address = new AnnotationModel.Address
{
City = "City"
},
Lodgings = new List <AnnotationModel.Lodging>
{
new AnnotationModel.Lodging
{
Name = "Lodging One"
},
new AnnotationModel.Lodging
{
Name = "Lodging Two"
}
},
Info = new AnnotationModel.PersonalInfo
{
DietryRestrictions = "DietryRestrictions",
Width = new AnnotationModel.Measurement
{
Reading = 2.1M,
Units = "Units"
},
Height = new AnnotationModel.Measurement
{
Reading = 3.1M,
Units = "Units2"
}
}
};
context.Destinations.Add(destination);
context.SaveChanges();
destinationId = destination.DestinationId;
}
using (var context = new BreakAwayContext())
{
var destination = context.Destinations.Single(d => d.DestinationId == destinationId);
context.Destinations.Remove(destination);
context.SaveChanges();
}
using (var context = new BreakAwayContext())
{
var lodgings = context.Lodgings.Where(l => l.DestinationId == destinationId).ToList();
Console.WriteLine("Lodgings: {0}", lodgings.Count);
}
}
static void Main(string[] args)
{
#if false
Database.SetInitializer(new InitializeBagaDatabaseWithSeedData());
using (var context = new BreakAwayContext())
{
try
{
/*
* force: Zwingt EF dazu die Datenbank an dieser Stelle zu initialisieren.
* false: Nur initialisieren wenn das Model noch nicht in der Datenbank ist.
* true: Immer neu Initialisieren.
*/
context.Database.Initialize(force: false);
Console.WriteLine("Initialization successfully");
}
catch (Exception ex)
{
Console.WriteLine("Initialization failed...");
Console.WriteLine(ex.Message);
}
}
#endif
Console.ReadKey();
}
/*
* public void ex01_AddNewDestination()
* {
* execute(ctx =>
* {
*
* });
* }
*/
#region private methods
private void execute(Action <BreakAwayContext> action)
{
using (var ctx = new BreakAwayContext())
{
ctx.Database.Log = sql => Trace.WriteLine(sql);
action(ctx);
}
}
private static void UpdateDestination(Destination destination)
{
using (var context = new BreakAwayContext())
{
context.Entry(destination).State = EntityState.Modified;
context.SaveChanges();
}
}
// Serversidesimulation
private static void AddDestination(Destination destination)
{
using (var context = new BreakAwayContext())
{
context.Destinations.Add(destination);
context.SaveChanges();
}
}
private static void AttachDestination(Destination destination)
{
using (var context = new BreakAwayContext())
{
context.Entry(destination).State = EntityState.Unchanged;
context.SaveChanges();
}
}
public void InsertsDestination(Destination destination)
{
using (var context = new BreakAwayContext())
{
context.Destinations.Add(destination);
context.SaveChanges();
}
}
private static void UpdateLodging(Lodging lodging)
{
using (var context = new BreakAwayContext())
{
context.Entry(lodging).State = EntityState.Modified;
context.SaveChanges();
}
}
private static void DeleteDestination(Destination destination)
{
using (var context = new BreakAwayContext())
{
context.Destinations.Attach(destination);
context.Destinations.Remove(destination);
context.SaveChanges();
}
}
public static void UpdateSocialSecurityNumber(int ssn)
{
using (var context = new BreakAwayContext())
{
var person = context.People.FirstOrDefault();
person.SocialSecurityNumber = ssn;
context.SaveChanges();
}
}
private static void GetLocalDestinationCountWithLoad()
{
using (var context = new BreakAwayContext())
{
context.Destinations.Load();
var count = context.Destinations.Local.Count;
Console.WriteLine("Destinations in memory: {0}", count);
}
}
private static void UpdateTrip()
{
using (var context = new BreakAwayContext())
{
var trip = context.Trips.FirstOrDefault();
trip.CostUSD = 750;
context.SaveChanges();
}
}
public static void UpdateTrip(int usd)
{
using (var context = new BreakAwayContext())
{
var trip = context.Trips.FirstOrDefault();
trip.CostUSD = usd;
context.SaveChanges();
}
}
static void UpdatePersonDestination()
{
using (var context = new BreakAwayContext())
{
var destination = context.Destinations.FirstOrDefault();
destination.Country = "Rowena";
context.SaveChanges();
}
}
public static void UpdatePerson()
{
using (var context = new BreakAwayContext())
{
var person = context.Persons.FirstOrDefault();
person.FirstName = "Rowena";
context.SaveChanges();
}
}
