Category Archives: ELP

[EN] Entity Framework Core – Code First migrations

In this post I want to show you how to create new database using Entity Framework Core – Code First migrations approach.

codefirst

I have project ELP.Model in which I defined few entities. I want to create database from it. It is approach called Code First. This is how looks one of my entity

public class Event : AuditableEntity<long>
    {
        [Required]
        [MaxLength(100)]
        public string Name { get; set; }
    }

 public class AuditableEntity<T> : Entity<T>, IAuditableEntity
    {
        [ScaffoldColumn(false)]
        public DateTime CreatedDate { get; set; }

        [MaxLength(256)]
        [ScaffoldColumn(false)]
        public string CreatedBy { get; set; }

        [ScaffoldColumn(false)]
        public DateTime UpdatedDate { get; set; }

        [MaxLength(256)]
        [ScaffoldColumn(false)]
        public string UpdatedBy { get; set; }
    }

 public abstract class Entity<T> : BaseEntity, IEntity<T>
    {
        public virtual T Id { get; set; }
    }

 public abstract class BaseEntity
    {
    }

  public interface IEntity<T>
    {
        T Id { get; set; }
    }

public class Event : AuditableEntity<long>

{

[Required]

[MaxLength(100)]

public string Name { get; set; }

}

public class AuditableEntity<T> : Entity<T>, IAuditableEntity

{

[ScaffoldColumn(false)]

public DateTime CreatedDate { get; set; }

[MaxLength(256)]

[ScaffoldColumn(false)]

public string CreatedBy { get; set; }

[ScaffoldColumn(false)]

public DateTime UpdatedDate { get; set; }

[MaxLength(256)]

[ScaffoldColumn(false)]

public string UpdatedBy { get; set; }

}

public abstract class Entity<T> : BaseEntity, IEntity<T>

{

public virtual T Id { get; set; }

}

public abstract class BaseEntity

{

}

public interface IEntity<T>

{

T Id { get; set; }

}

To be able to enable migration and create database, we need to create Context. My Context Class looks like this

 public class ELPContext : DbContext, IContext
    {
        public ELPContext(DbContextOptions dbContextOptions) : base(dbContextOptions)
        {
        }

        public DbSet<Event> Events { get; set; }
        public DbSet<User> Users { get; set; }
        public DbSet<Role> Roles { get; set; }
        public DbSet<UserRole> UserRoles { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            base.OnConfiguring(optionsBuilder);
        }

        public override int SaveChanges()
        {
            var modifiedEntries = ChangeTracker.Entries()
                .Where(x => x.Entity is IAuditableEntity
                    && (x.State == EntityState.Added || x.State == EntityState.Modified));

            foreach (var entry in modifiedEntries)
            {
                IAuditableEntity entity = entry.Entity as IAuditableEntity;
                if (entity != null)
                {
                    DateTime now = DateTime.UtcNow;

                    if (entry.State == EntityState.Added)
                    {
                        entity.CreatedDate = now;
                    }
                    else
                    {
                        base.Entry(entity).Property(x => x.CreatedBy).IsModified = false;
                        base.Entry(entity).Property(x => x.CreatedDate).IsModified = false;
                    }
                    entity.UpdatedDate = now;
                }
            }

            return base.SaveChanges();
        }
    }

public class ELPContext : DbContext, IContext

{

public ELPContext(DbContextOptions dbContextOptions) : base(dbContextOptions)

{

}

public DbSet<Event> Events { get; set; }

public DbSet<User> Users { get; set; }

public DbSet<Role> Roles { get; set; }

public DbSet<UserRole> UserRoles { get; set; }

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

{

base.OnConfiguring(optionsBuilder);

}

public override int SaveChanges()

{

var modifiedEntries = ChangeTracker.Entries()

.Where(x => x.Entity is IAuditableEntity

&& (x.State == EntityState.Added || x.State == EntityState.Modified));

foreach (var entry in modifiedEntries)

{

IAuditableEntity entity = entry.Entity as IAuditableEntity;

if (entity != null)

{

DateTime now = DateTime.UtcNow;

if (entry.State == EntityState.Added)

{

entity.CreatedDate = now;

}

else

{

base.Entry(entity).Property(x => x.CreatedBy).IsModified = false;

base.Entry(entity).Property(x => x.CreatedDate).IsModified = false;

}

entity.UpdatedDate = now;

}

return base.SaveChanges();

}

We need to install few packages before we start with actual migration.

To do it, open Package Manager Console (In VS Tools-> Nuget Package Manager -> Package Manager Console) set Default Project to your target project and install packages. Make sure to install the newest versions or the same versions for all.

Install-Package Microsoft.EntityFrameworkCore

Install-Package Microsoft.EntityFrameworkCore.SqlServer

Install-Package Microsoft.EntityFrameworkCore.Tools

Install-Package Microsoft.EntityFrameworkCore

Install-Package Microsoft.EntityFrameworkCore.SqlServer

Install-Package Microsoft.EntityFrameworkCore.Tools

To enable migrations in our project first we need to type in the same console Add-Migration MigrationName

Add-Migration InitialMigration

1	Add-Migration InitialMigration

and here is surprise. Not so easy man. I missed something. Yes exactly, we need to add implementation of IDbContextFactory<ELPContext>

This class should look like this:

 public class ELPContextFactory : IDbContextFactory<ELPContext>
    {
        public ELPContext Create(DbContextFactoryOptions options)
        {
            var builder = new DbContextOptionsBuilder<ELPContext>();
            builder.UseSqlServer("Server=(localdb)\\mssqllocaldb;Database=ELPdb;Trusted_Connection=True;MultipleActiveResultSets=true");
            return new ELPContext(builder.Options);
        }
    }

public class ELPContextFactory : IDbContextFactory<ELPContext>

{

public ELPContext Create(DbContextFactoryOptions options)

{

var builder = new DbContextOptionsBuilder<ELPContext>();

builder.UseSqlServer("Server=(localdb)\\mssqllocaldb;Database=ELPdb;Trusted_Connection=True;MultipleActiveResultSets=true");

return new ELPContext(builder.Options);

}

Another Try to Add Migration and … another error…

What da… !? It looks like it is an issue in EF Core v 1.1.0. Work around for it is to change version to 1.0 :/ To do it we need to modify TargetFramework in csproj file from netcoreapp1.1 to netcoreapp1.0

Another try

Add-Migration InitialMigration

1	Add-Migration InitialMigration

Uff now everything works fine.

Take a look into Solution Explorer. Here we have new classes and Migrations folder.

The last step is to execute Update-Database command in Package Manager Console.

Update-Database

1	Update-Database

Fortunately this time it worked for me in first try. I didn’t expect it will be so easy 😉

To verify it, open SQL Server Object Explorer and check it. It should create new database.

Yeah, we have created database, nice. Now we can add something to it 🙂

[EN] How to mock DbSet in Entity Framework

duck as mock

In my project ELP I decided to start with core implementation of backend side. I started with service for sign in and register user accounts. I use TDD approach, so I create test with expected result that fails at the beginning and then I implement code to pass this test.

I created MembershipService in my project that is responsible for creating accounts, validating, etc. This service uses other services like UserService for getting users from database or UserRoleService for getting user roles. Services use context, (BTW I rejected using repository pattern, maybe I will describe more about it in the future) and context contains DbSets.

 public class UserService : EntityService<User>, IUserService
    {      
        public UserService(IContext context) : base(context)
        {
        }

        public User GetUserByUsername(string username)
        {
            return _dbset.FirstOrDefault(u => u.Username == username);
        }
    }

public class UserService : EntityService<User>, IUserService

{

public UserService(IContext context) : base(context)

{

}

public User GetUserByUsername(string username)

{

return _dbset.FirstOrDefault(u => u.Username == username);

}

First problem that you can meet is how to mock this thing?

Let’s see how to write a test for method GetUserByUsername.

  [Fact]
        public void GetUserByUsernameTest()
        {
            string username = "testUser1";
            var ctx = new Mock<IContext>();
            List<User> users = new List<User>();
            users.Add(new User() { Username = username});
            var mockDbSet = ServiceTestsHelper.GetMockDbSet<User>(users);            
            ctx.Setup(c => c.Set<User>()).Returns(mockDbSet.Object);
            IUserService service = new UserService(ctx.Object);
            var result = service.GetUserByUsername(username);
            Assert.NotNull(result);
        }

[Fact]

public void GetUserByUsernameTest()

{

string username = "testUser1";

var ctx = new Mock<IContext>();

List<User> users = new List<User>();

users.Add(new User() { Username = username});

var mockDbSet = ServiceTestsHelper.GetMockDbSet<User>(users);

ctx.Setup(c => c.Set<User>()).Returns(mockDbSet.Object);

IUserService service = new UserService(ctx.Object);

var result = service.GetUserByUsername(username);

Assert.NotNull(result);

}

This is my test. I use xUnit testing framework and Moq for mocking. If you want to use it as I, you need to install it from Nuget Packages manager.

As you see I created list with one user and I want to pass it to my context, It will act like data get from database. First we need to create our DbSet for Users. I have little helper method for it. It is generic, so you can use it too.

internal static Mock<DbSet<T>> GetMockDbSet<T>(ICollection<T> entities) where T : class
        {
            var mockSet = new Mock<DbSet<T>>();
            mockSet.As<IQueryable<T>>().Setup(m => m.Provider).Returns(entities.AsQueryable().Provider);
            mockSet.As<IQueryable<T>>().Setup(m => m.Expression).Returns(entities.AsQueryable().Expression);
            mockSet.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(entities.AsQueryable().ElementType);
            mockSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(entities.AsQueryable().GetEnumerator());
            mockSet.Setup(m => m.Add(It.IsAny<T>())).Callback<T>(entities.Add);
            return mockSet;
        }

internal static Mock<DbSet<T>> GetMockDbSet<T>(ICollection<T> entities) where T : class

{

var mockSet = new Mock<DbSet<T>>();

mockSet.As<IQueryable<T>>().Setup(m => m.Provider).Returns(entities.AsQueryable().Provider);

mockSet.As<IQueryable<T>>().Setup(m => m.Expression).Returns(entities.AsQueryable().Expression);

mockSet.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(entities.AsQueryable().ElementType);

mockSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(entities.AsQueryable().GetEnumerator());

mockSet.Setup(m => m.Add(It.IsAny<T>())).Callback<T>(entities.Add);

return mockSet;

}

Ok, so first test we have completed, but there’s one more thing that I wanted to share with you.

Let’s get back to my service that I mentioned before – MembershipService. I’d like to test CreateUser method which at the end adds user entity to User’s DbSet. Problem is with verifying it if you use mocks. If you check User’s DbSet from Context class there’s nothing in it. Null. And here comes Verify method from Moq framework that helps.

Here are 3 lines of code from my testing method, it executes CreateUserMethod, so I expect User’s DbSet will contain one item and UserRole’s DbSet will contain two items.

User result = service.CreateUser("testUser1", "test@email.com", "password", new List<int>() { 1, 2 });
usersMockDbSet.Verify(m => m.Add(It.IsAny<User>()), Times.Once);
userRolesMockDbSet.Verify(m => m.Add(It.IsAny<UserRole>()), Times.Exactly(2));

User result = service.CreateUser("testUser1", "test@email.com", "password", new List<int>() { 1, 2 });

usersMockDbSet.Verify(m => m.Add(It.IsAny<User>()), Times.Once);

userRolesMockDbSet.Verify(m => m.Add(It.IsAny<UserRole>()), Times.Exactly(2));

With help of Verify method result is as expected and test is green.

If you want to read more about testing Entity Framework you can go to https://msdn.microsoft.com/en-us/library/dn314429(v=vs.113).aspx

[EN] Creating Angular2 CLI project

What is Angular2 CLI?

Angular2 CLI is Command Line Interface introduced by Angular team, to help us develop applications in Angular 2, through automate some operations and keep consistent project structure. You may think it’s a waste of time to learn another new thing, but I encourage you to use CLI, even if you are new to Angular. It’s even more helpful in this case, because with CLI your development will be faster and easier.

Before we start make sure you have node.js installed on your machine. If not, you can download it here https://nodejs.org/en/download/. It is essential to develop Angular applications.

Let’s start

To create new Angular2 CLI project, open your command line tool. At the beginning you need to install angular CLI, to do it type:

npm install -g @angular/cli

1	npm install -g @angular/cli

Wait for a while, take a beer or yerba mate if you prefer and come back after few minutes 😛

Then type command that will create new project, something like this:

ng new PROJECT_NAME

1	ng new PROJECT_NAME

Where PROJECT_NAME is any name for your project. As you can see you need to wait for install packages via npm, so take another beer don’t waste your time 😉

After that go to project location, dig in your project folder, type cd PROJECT_NAME. You will se new files and folders here like on image below. This is our brand new project.

And let’s do the magic. Type ng serve and you will see… an error maybe, but you should’n if everything you did before correctly. If everything works fine your console output should looks like this:

Open your browser and type http://localhost:4200 you should see:

It means you have working app! Congrats ;0

For developing our front end side of application, I recommend you Visual Studio Code Editor. You can download it here. https://code.visualstudio.com/

Open whole folder of your new application in VS Code

That’s it. Project structure and other Angular2 CLI features I will cover in the next posts.

[EN] How to create ASP.NET Core project using Visual Studio 2017

In this post I would like to show you how to create ASP.NET Core project using Visual Studio 2017. I’m using VS Community RC edition, but it’s not so important, you can use different edition. So, let’s create new empty solution and then add new Project.

I want to create ASP.NET Core Web API project. Let’s choose correct template then.

You will see new window where you can choose ASP.NET Core Template. I want to create Web API so I’m choosing it. You can choose authentication on the right hand side (Work or School Accounts or Windows Authentication), but I don’t want it. There’s also one very interesting feature here, look at the bottom of this window – there’s option to enable Docker support – WOW, but we will take a look at it maybe later 🙂 Yes, docker is also a thing that I want to learn about in practice.

Ok and project is created. It’s good to test our app if everything is ok. Push F5 and check. You should see new browser tab which displays:

[„value1″,”value2”]

Don’t worry, it means it’s fine 🙂 Project is ready, we can start to work on our API.

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Jakub Skoczeń

.NET Developer

Category Archives: ELP

[EN] Entity Framework Core – Code First migrations

[EN] How to mock DbSet in Entity Framework

[EN] Creating Angular2 CLI project

What is Angular2 CLI?

Let’s start

[EN] How to create ASP.NET Core project using Visual Studio 2017