Delivering solid user friendly software solutions since the dawn of time.

Code First 

Categories: EF

O'Reilly's Programming Entity Framework - Code First

By Julia Lerman & Rowan Miller

  • Table name will be plural of class name created with dbo schema.
  • Column names same as properties they map to.
  • Strings are mapped to nvarchar(max)
  • Byte[] is mapped to varbinary(max)
  • Bool to bit not null
  • A class must have a key property (default named Id or typenameId)
  • One-to-Many Relationships with foreign key [Name of navigation property]_[Primary key of related class]
  • Foreign keys are nullable by convention.
  • In memory metadata created from code or EDMX model (System.Data.Metadata.Edm)
  • Only use DetectChanges if needed for performance tuning.

Data Annotations (System.ComponentModel.DataAnnotations) vs Fluent API (modelBuilder.Entity<AnimalType>())


[Table("Species", Schema="baga")]
this.ToTable("Species", "baga");

this.Property(d => d.Nam).HasColumnName("LocationName");

this.HasKey(t => t.Guid);

this.Property(p => p.TypeName).IsRequired();

[MinLength(10), MaxLength(500)]
this.Property(p => p.Description).HasMaxLength(500); (no min available)

this.Property(d => d.Photo).HasColumnType("image");

this.Property(t => t.Guid).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

[Timestamp] must be a byte[]
this.Property(t => t.TimeStamp).IsRowVersion();

this.Property(t => t.SocialSecurityNumber).IsConcurrencyToken();


modelBuilder.Entity<User>().HasRequired(a => a.BillingAddress).WithMany().HasForeignKey(u => u.BillingAddressId);

modelBuilder.Entity<PersonPhoto>().HasRequired(p => p.PhotoOf).WithRequiredDependent(p => p.Photo);

modelBuilder.Entity<Lodging>().HasOptional(l => l.PrimaryContact).WithMany(p => p.PrimaryContactFor);

this.Property(t => t.SomeAscii).IsUnicode(false);

this.Property(t => t.SomeMiles).HasPrecision(8,1);


Ignore(d => d.TodayForecast);
  • By default, Code First will create the database only if it doesn't already exist.
  • Complex types have no key property, can only contain primitive properties and when used as a property in another class, the property must represent a single instance. It cannot be a collection type. [HostPropertyName_PropertyName]
  • Entity.Has[Multiplicity](Property).With[Multiplicity](Property)
  • .HasOptional, .HasRequired, .HasMany + WithOptional, WithRequired, WithMany
  • [Target Type Key Name], [Target Type Name] + [Target Type Key Name], [Navigation Property Name] + [Target Type Key Name]
var tripWithActivities = context.Trips.Include("Activities").FirstOrDefault();

Table splitting

Entity splitting
Map(m => { m.Properties(d => new { d.Name, d.Country, d.Description }); m.ToTable("Locations"); });
Map(m => { m.Properties(d => new { d.Photo }); m.ToTable("LocationPhotos"); });
  • For protected and private properties, the configuration class must be nested inside the class that is part of the model.
  • The setter can be marked with a more restrictive accessor, but the getter must remain public for the property to be mapped automatically. (not supported in medium trust because of reflection)
public class Person
public int PersonId { get; set; }
private string Name { get; set; }

public class PersonConfig : EntityTypeConfiguration<Person>
public PersonConfig()
Property(b => b.Name);

public string GetName()
return this.Name;

public static Person CreatePerson(string name)
return new Person { Name = name };
modelbuilder.Configuration.Add(new Person.PersonConfig());

public string FullName
get { return String.Format("{0}{1}",FirstName.Trim(), LastName); }

Table per hierarchy (TPH) describes mapping inherited types to a single database table that uses a discriminator column to differentiate one subtype from another. This is default for Entity Framework. (nvarchar(128), not null containing the type name)

  • Map(m => { m.ToTable("Lodgings"); m.Requires("LodgingType").HasValue("Standard"); });
  • Map<Resort>(m => { m.Requires("LodgingType").HasValue("Resort"); });
  • Map(m => { m.ToTable("Lodgings"); m.Requires("IsResort").HasValue(false); });
  • Map<Resort>(m => { m.Requires("IsResort").HasValue(true); });

Table per type (TPT) only stores properties for base class in a single table. Additional properties are stored in separate table.

  • modelBuilder.Entity<Resort>().ToTable("Resorts");
  • modelBuilder.Entity<Lodging>().Map<Resort>(m => { m.ToTable("Resorts"); });

Table per concrete type (TPC) stores all the properties for each type in a separate table. Map inheritance to tables with common overlapping fields.

  • modelBuilder.Entity<Lodging>().Map(m => { m.Table("Lodgings"); }).Map<Resort>(m => { m.ToTable("Resorts"); m.MapInheritedProperties(); } );

Mapping foreign keys

  • HasRequired(l => l.Destination).WithMany(d => d.Lodgings).Map(c => c.MapKey("destination_id"));
  • HasRequired(l => l.Destination).WithMany(d => d.Lodgings).Map(c => c.MapKey("destination_id").ToTable("LodgingInfo"));
  • HasMany(t => t.Activities).WithMany(a => a.Trips).Map(c => c.ToTable("TripActivities"));
  • HasMany(t => t.Activities).WithMany(a => a.Trips).Map(c => { c.ToTable("TripActivities"); c.MapLeftKey("TripIdentifier"); c.MapRightKey("ActivityId"); });
  • MapLeftKey affects the foreign key column that points to the class being configured!


// you need to take care of disposing the connection unless your context owns the connection (property)
using (var connection = new SqlConnection(connectionString))
using (var db = new MyDbContext(connection)) { ... }
using (var dbUsingSameConnection = new MyDbContext(connection)) { ... }
  • SqlConnectionFactory : IDbConnectionFactory
  • Database.DefaultConnectionFactory = new SqlCeConnectionFactory("System.Data.SqlServerCe.4.0");

Initialization is triggered the first time that the context is used. Initialization occurs lazily.

  • Database.SetInitializer(new DropCreateDatabaseIfModelChanges<BreakAwayContext>());
  • Database.SetInitializer(new CreateDatabaseIfNotExists<BreakAwayContext>());
  • Database.SetInitializer(new DropCreateDatabaseAlways<BreakAwayContext>()); // use system.Transactions.TransactionScope if you have a lot of integration tests
  • EFCodeFirst.CreateTablesOnly nuget package
using (var context = new BreakAwayContext())
context.Database.Initialize(force: false);
catch (Exception ex) { ... }
Database.SetInitializer(null); // do not magically create a database
<add key="DatabaseInitializerForType DataAccess.BreakAwayContext, DataAccess" value="Disabled" />

public class PromptForDropCreateDatabaseWhenModelChanges<TContext> : IDatabaseInitializer<TContext> where TContext : DbContext
public void InitializeDatabase(TContext context)
var exists = context.Database.Exists();
if (exists && context.Database.CompatibleWithModel(true)) return;
if (exists)
// prompt

public class DropCreateBreakAwayWithSeedData : DropCreateDatabaseAlways<BreakAwayContext>
protected override void Seed(BreakAwayContext context)
context.Database.ExecuteSqlCommand("CREATE INDEX IX_Lodgings_Name ON Lodgings (Name)");
context.Destinations.Add(new Destination { Name = "foo" });

Mapping to Updatable views

Using views to populate objects

var destinations = context.Destinations.SqlQuery(@"SELECT Id AS DestinationId, Name FROM dbo.TopTenDestinations");

public class DestinationSummary
public int DestinationId { get; set; }
public string Name { get; set; }
public int ResortCount { get; set; }
var summary = context.Database.SqlQuery<DestinationSummary>("SELECT * FROM dbo.DestinationSummaryView");

Stored Procedures

var country = "Belgium";
var keywords ="sun, yeahright";
var destinations = context.Database.SqlQuery<DestinationSummary>("dbo.GetDestinationSummary @p0, @p1", country, keywords);

Removing Conventions

  • modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

Model Caching

  • Using the same DbCompiledModel to create contexts against different types of database servers is not supported. Instead, create a separate DbCompiledModel for each type of server being used.

var sql_model = GetBuilder().Build(new DbProviderInfo("System.Data.SqlClient", "2008")).Compile();
var context = new BreakAwayContext (connection, sql_model);
public static DbModelBuilder GetBuilder()
var builder = new DbModelBuilder();
return builder;

EdmMetadata Table

  • Snapshot of your model as a SHA256 hash.
  • var modelHash = EdmMetadata.TryGetModelHash(context);
  • var databaseHash = context.Set<EdmMetadata>().Single().ModelHash;
  • var compatible = context.Database.CompatibleWithModel(throwIfNoMetadata:true);
  • modelBuilder.Conventions.Remove<IncludeMetadataConvention>();


Multiple objects sets per type are not supported 

Categories: EF

You copy and pasted a DbSet and then you forget to rename the type...

This error occurs if your DbContext class exposes multiple DbSet<T> properties where T occurs more than once. Entitfy framework is not able to figure out which DbSet an instance of type T belongs to.

public DbSet<Course> Courses { get; set; }
public DbSet<Course> Chapters { get; set; }

Database diagram support objects cannot be installed because this database does not have a valid owner 

Categories: SQL Server

Microsoft SQL Server Management Studio
Database diagram support objects cannot be installed because this database does not have a valid owner. To continue, first use the Files page of the Database Properties dialog box or the ALTER AUTHORIZATION statement to set the database owner to a valid login, then add the database diagram support objects.


  1. Right Click on your database, choose properties
  2. Goto the Files
  3. Change the owner textbox to "sa"
  4. Press OK

Git Fundamentals - Notes 

Categories: Tortoise

by James Kovacs


  • Git created by Linus Torvalds, who also created Linux (because Bit-Keeper started asking him money)
  • Written in Perl and C

Advantages of DVCS

  • Different topologies (centralized, hierarchical, distributed)
  • Each clone is a full backup
  • Reliable branching/merging
  • Full local history (statistics, analyze regressions)
  • Deployment



  • brew install git
  • DMG (http://git-scm.com/download/mac)


  • sudo apt-get install git-core (Debian/Ubuntu)
  • yum install git-core


git --version
git config --system (c:\Program Files\Git\etc\gitconfig)
git config --global (c:\Users\user\.gitconfig)
git config (stored in .git/config in each repo)

git config --global --list
git config --global help.autocorrect 1 (corrects your mispelled command)
git config --global color.ui auto
git config --global core.autocrlf true|false|input

git init

git status
git add foo.txt
git commit -m "my text"

git log

git diff dd6819..a15ec6
git diff HEAD~1..HEAD (~1 is one back from head revision)

git add -u (only adds updated files)
git add -A (all even untracked)

git checkout foo.txt (revert changes)
git reset --hard (revert all to head)
git reset --soft HEAD~1 (reorganize version)

git clean -n|-f (remove)


git clone https://foo.repo
git log --oneline | wc=1
git shortlog -sne (short name include number of commits and email)

git remote -v (where does the source come from)

git branch -r (include remote branches)

git remote add origin https://apullrequest
git fetch
git log origin/master
git merge origin/master
git branch -r

git branch --set-upstream master origin/master
git pull (shortcut of fetching and merging from an origin)
git remote add origin git@github.com:JamesKovacs/GitFundamentals.git (uses ssh key)
git push

git tag v1.0
git tag -a v1.0_with_message
git tag -s v1.0_signed
git push --tags


  • https 80/443 https://github.com/jquery/jquery.git
  • git 9418 git://github.com/jquery/jquery.git
  • ssh 22 git@github.com:jquery/jquery.git
  • file n/a filepath

Branching, Merging, and Rebasing with Git

git log --graph --oneline --all --decorate
git config --global alias.lga "log --graph --oneline --all --decorate"
git lga
git reflog (about 30 days to get delete back)
git stash (rollback pending changes)
git stash list
git stash apply
git stash pop (apply and remove)
git stash drop
git stash branch 'feature2_additional'

git mergetool (eg. KDiff3, BeyondCompare)
git checkout bug1234
git rebase master
git rebase --continue

git branch v1.0_fixes v1.0
git checkout v1.0_fixes
git commit -am "Added fix1"
git commit -am "Added fix2"
git checkout master
git cherry-pick 6fa4324

git fetch origin master
git push
git push origin v1.0_fixes


xcopy exit with code 9009 in Visual Studio post-build 

Categories: Visual Studio

Yep, you probably did some windows updates. Things got a bit more strict, when you are not running command windows as administrator some executables are no longer found. And this is also for your visual studio post build events.

I just added C:\Windows\System32\ in front of the xcopy command and it solved things. In mean time also check that you didn't at some additional line breaks on accident. But if you like, you can also add the system directory back to your windows path. You can find this at computer - properties - advanced system settings - environment variables - system variables - path. 

So for example:
C:\Windows\System32\xcopy /s /y "$(ProjectDir)bin\ken.MojoPortal.HtmlTools.Web.dll" "$(SolutionDir)Web\bin\"

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