XpressionMapper.NetCore

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What is XpressionMapper?

XpressionMapper.NetCore leverages AutoMapper version 5.2 and .Net Standard Library version 1.6.1 to transform business model expressions into data model expressions.

Expression mapping provides a couple of advantages:

1. Improved separation of concerns: The Entity Framework (or other ORM) layer has no knowledge of the business model.
2. Removes the need for projection in the data layer or the need to return an IQueryable object from the data layer.

How it works?

The service layer references business model classes only and has no knowledge of the data model (POCOs) or the EF (Entity Framework) layer

public class PersonService : IPersonService
{
    private IPersonRepository repository;
public ICollection<PersonModel> GetList(Expression<Func<PersonModel, bool>> filter = null, Expression<Func<IQueryable<PersonModel>, IQueryable<PersonModel>>> orderBy = null, ICollection<Expression<Func<IQueryable<PersonModel>, IIncludableQueryable<PersonModel, object>>>> includeProperties = null)
{
    ICollection<PersonModel> list = repository.GetList(filter, orderBy, includeProperties);
    return list.ToList();
}

}

The repository layer references the business model and data model (POCOs) classes and has no knowledge of the EF layer. public class PersonRepository : IPersonRepository { private IPersonStore store;

    public ICollection<PersonModel> GetList(Expression<Func<PersonModel, bool>> filter = null, Expression<Func<IQueryable<PersonModel>, IQueryable<PersonModel>>> orderBy = null, ICollection<Expression<Func<IQueryable<PersonModel>, IIncludableQueryable<PersonModel, object>>>> includeProperties = null)
    {
        Expression<Func<Person, bool>> f = filter.MapExpression<Func<PersonModel, bool>, Func<Person, bool>>();
        Expression<Func<IQueryable<Person>, IQueryable<Person>>> mappedOrderBy = orderBy.MapExpression<Func<IQueryable<PersonModel>, IQueryable<PersonModel>>, Func<IQueryable<Person>, IQueryable<Person>>>();
        ICollection<Expression<Func<IQueryable<Person>, IIncludableQueryable<Person, object>>>> includes = mapper.MapIncludesList<Func<IQueryable<PersonModel>, IIncludableQueryable<PersonModel, object>>, Func<IQueryable<Person>, IIncludableQueryable<Person, object>>>(includeProperties);

        ICollection<Person> list = store.Get(f,
                mappedOrderBy == null ? null : mappedOrderBy.Compile(),
                includes == null ? null : includes.Select(i => i.Compile()).ToList());
        return Mapper.Map<IEnumerable<Person>, IEnumerable<PersonModel>>(list).ToList();
    }
}

The EF layer references the data model (POCOs) and has no knowledge of the business model.

public class PersonStore : IPersonStore
{
    public IList<Person> Get(Expression<Func<Person, bool>> filter = null, Func<IQueryable<Person>, IQueryable<Person>> orderBy = null, ICollection<Func<IQueryable<Person>, IIncludableQueryable<Person, object>>> includeProperties = null)
    {
        IList<Person> list = null;
        using (IPersonUnitOfWork unitOfWork = new PersonUnitOfWork())
        {
            list = new PersonDbMapper(unitOfWork).Get(filter, orderBy, includeProperties);
        }

        return list;
    }
}

To get started:

• Run the .NET Core 1.1 SDK - Installer and Visual Studio 2015 Tools (Preview 2) from here.
• Build the Solution.

Create the database

• Search the solution for "Server=.\SQL2016;Database=SchoolDb02" and update connection strings if necessary.
• Open a command window at {Solution Folder}\src\MigrationTool then execute following command:
  • dotnet ef database update

Seed the database

Execute StoreTestConsole to seed the database.

Run the Web API Solution

Set ContosoUniverity.WebApi as the start up project and press CTRL+F5 to run the Web API project.

To run the Angular 2 project:

Get the latest versions of nodejs and npm as described here. Open a command window at {Solution Folder}\src\ContosoUniverity.Angular2.Web and run:

• npm install
• npm install -g angular-cli
• ng serve

Open the browser as described in the output. NG Live Development Server is running on http://localhost:{port#}.